Wombats (Australian Natural History Series)

AUSTRALIAN NATURAL HISTORY SERIES

WOMBATS SECOND EDITION

BARBARA TRIGGS

AUSTRALIAN NATURAL HISTORY SERIES

WOMBATS SECOND EDITION

BARBARA TRIGGS

© Barbara Triggs 2009 All rights reserved. Except under the conditions described in the Australian Copyright Act 1968 and subsequent amendments, no part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, duplicating or otherwise, without the prior permission of the copyright owner. Contact CSIRO PUBLISHING for all permission requests. National Library of Australia Cataloguing-in-Publication entry Triggs, Barbara. Wombats / Barbara Triggs. 2nd ed. 9780643096011 (pbk.) Includes index. Bibliography. Wombats. 599.24 Published by CSIRO PUBLISHING 150 Oxford Street (PO Box 1139) Collingwood VIC 3066 Australia Telephone: Local call: Fax: Email: Web site:

+61 3 9662 7666 1300 788 000 (Australia only) +61 3 9662 7555 [email protected] www.publish.csiro.au

Front cover Bare-nosed wombat. Photo © Dave Watts. Back cover Northern hairy-nosed wombat (left) and southern hairy-nosed wombat (right). Photos © Dave Watts. Set in 10.5/14 Adobe Palatino, Optima and Stone Sans Edited by Janet Walker Cover and text design by James Kelly Typeset by Desktop Concepts Pty Ltd, Melbourne Printed in Hong Kong by Bookbuilders CSIRO PUBLISHING publishes and distributes scientific, technical and health science books, magazines and journals from Australia to a worldwide audience and conducts these activities autonomously from the research activities of the Commonwealth Scientific and Industrial Research Organisation (CSIRO). The views expressed in this publication are those of the author(s) and do not necessarily represent those of, and should not be attributed to, the publisher or CSIRO.

CONTENTS Preface

iv

1

Evolution and early history

1

2

The wombat itself

13

3

Burrows

21

4

What goes on in a burrow?

35

5

Life above ground

41

6

From birth to maturity

69

7

Dangers, disorders and disasters

99

8

Wombats in the wardrobe

123

Appendix 1: Growth and development

133

Appendix 2: Hand-rearing orphan wombats

134

References and further reading

141

Index

151

PREFACE When the revised edition of The Wombat was published in 1996 I bemoaned the fact that wombats were the ‘poor relations’ when it comes to scientific research. Thankfully, this has been rectified to a certain extent and much more is now known about the secret lives of the three species of wombats. In this book I have tried to include this new information. Much of the text deals with the bare-nosed wombat but wherever possible I have added information on the two hairy-nosed species. Early in my investigations in the 1970s I discovered that wombats are not easy animals to study. Much of their lives are spent underground, and even when they are active above ground it is usually dark or nearly so. They are also extremely wary and have an excellent sense of smell and acute hearing, but I found that if I stood absolutely still, downwind, they would be unaware of my presence. Following them through the forest undergrowth so that I was close enough to see what they were doing required much patience and stealth and was often unsuccessful. There is also considerable difficulty in observing social interactions between animals that spend most of their time either alone or deliberately avoiding one another. Field studies of mammals, particularly nocturnal ones, are usually carried out by first catching or trapping the animals and tagging them in some way, so that individuals can be recognised at a distance or when retrapped. Radio-collars or similar devices are often attached to some of the animals and their movements monitored by radio-tracking. Much of the information about wombats has been gathered in this way, and, more recently, by remote censusing, which involves genetic research. Not having the resources or the expertise needed to obtain and use any of these methods in my studies of wombats, I relied on knowing the wombats so well that I could identify them, even in poor light. This is surprisingly easy – every wombat has enough individual characteristics that can be used to distinguish it from any other wombat, such as coat colour, scars on various parts of the body, size and face shape. It is also often possible to determine the sex of a wombat without having to trap it. Females with large pouch young or young at heel are easily identified, while males can usually be spotted when they sit down to scratch, as the large scrotum is often visible at that time. The occasional use of nightvision equipment and, more often, a red-light torch, helped my observations iv

Preface

and I recorded the wombats’ movements and behaviour on simple check sheets and a tape-recorder. My method had, and still has, many drawbacks. Following an animal in the forest at night is sometimes hazardous and often uncomfortable, but it is also deeply satisfying. There is a special thrill, a kind of magic, about watching animals in the wild when they are unaware of our presence or are indifferent to it. In the 1990s I visited an area in northern Tasmania where the wombats are often out and about in daylight and I have returned there many times. Watching them there is pure delight. The Narawntapu National Park is a place every wombat-lover should visit. Although much had been learned about wombats, there are still many aspects of their natural history that are not known or understood. This book is my attempt to record the information that has been published by many well-qualified researchers, as well as what I have managed to find out about them. A great many people have helped me to write this book and its earlier version, and in the study of wombats over the last 30 years. It would be impossible to list all of them here, but I wish to thank them all. There are some to whom I am especially indebted for allowing me to draw on their work, both published and unpublished, and for critically reading the manuscript or parts of it for the earlier edition, especially John McIlroy, Graham Brown, Rod Wells, Bob Green, the late John Seebeck and Paul Presidente. In gathering material for this book I have had valuable input from Alan Horsup and Rod Wells and I thank them both for their help. Many others have assisted me with ideas, criticism and encouragement, have provided access to wombats, information on development of young, data for the distribution maps, reference papers, identification of plant and scat material, and helped in many other ways. I also wish to thank all those who provided photographs, not only those who have been acknowledged in the relevant captions but also those whose photographs I was unable to use but which provided me with valuable reference material. Although there is not space to acknowledge all these people individually I am especially indebted to Martin Schulz, Clive Marks, Peter Canty, Hans Brunner, Wendy and Derek Falconer, Paul Kelly, Janet Lanyon, Heather Meek, Colin and Vi Merrett, Pauline Reilly, Helen and Jim Scott, Greg Young, Manfred Heide and Sheryn Woon. Tony Mitchell, Nick Mooney and other officers of the wildlife authorities of all states were also most helpful. I also wish to thank the rangers and staff of the Narawntapu National Park and Dorothy Chalmers for her assistance in the field there. Amanda v

Wombats

Cox of the Wombat Protection Society went out of her way to help me with information and photographs and I sincerely thank her. I am also very grateful to the illustrators – Peter Schouten, Jonathan Guy and Trish Wright – whose work enhances the book. Finally I want to thank the wombats themselves, the wild ones who put up with my presence and the orphans who taught me so much, for the endless delight they have given, and continue to give me. May they always be there.

vi

1 EVOLUTION AND EARLY HISTORY

Australia – a lush subtropical forest Wombats are ancient animals. Marsupials – the pouched mammals, of which the wombat is one – evolved about 100 million years ago, but the Australian fossil record is woefully sparse. The oldest known marsupial fossils are about 24 million years old, but very little is known about the early marsupials until the period that began about 15 million years ago. At that time, when much of Australia, including the now arid centre, was covered by lush subtropical forest, wombat-like marsupials were roaming the forest floor. Dolphins played in large freshwater lakes that spread over large areas of what is now central Australia. In the region we call the Simpson Desert, the trees were the homes of possums, gliders and koalas, while small rabbit-sized kangaroos hopped along the gullies, and large lion-sized carnivorous marsupials, Thylacaleo, hunted their prey. These animals were the ancestors of the ones we know today, and although not enough fossils have yet been found to establish a complete 1

Wombats

Figure 1.1 Sites at which some fossil wombats have been found. The scientific names of the fossil wombats are given in brackets.

family tree, we do know something about the links between these ancient forms and their modern relatives and about the course of events that influenced their evolution. Many of the mammals that were evolving between about 15 and five million years ago were developing larger and larger bodies, and as the world approached the Ice Ages of the Pleistocene some giant forms evolved, with more developing as time went on: several species of giant kangaroos, mighty marsupial lions, and the largest marsupial of all, the Diprotodon – a huge lumbering herbivore, up to two metres high at the shoulder and three metres long, about the size of a large rhinoceros. By the mid-Pleistocene the wombats were giant too. The scientific names of some of these fossil wombats and the sites at which the fossils were found are shown in Figure 1.1. The largest, Phascolonus gigas (Greek phaskolos, a pouch; gigas, giant), weighed up to 100 kilograms. Fossil remains of this giant extinct wombat have been found in many parts of Australia (Figure 1.2). Stockily built, the Pouched Giant was more than twice the size of the largest wombat seen today, but its feet were not as well adapted for digging as those of the modern wombat, so it may not have dug the cavernous burrows that its massive bulk would have needed (Figure 1.3). 2

Evolution and early history

Figure 1.2 Sites at which Phascolonus gigas fossils have been found.

Figure 1.3 Phascolonus gigas was more than twice the size of a modern wombat. Illustration: © Peter Schouten

3

Wombats

Phascolonus gigas and many of the other giant marsupials were probably still flourishing when people first came to Australia, at least 50 000 years ago. By this time too, the two kinds (genera) of wombats living today – those with bare, leathery noses, the Vombatus genus, and those with hairy noses, the Lasiorhinus genus (Greek lasio, hairy; rhinus, nose) – were widely established over the country. These genera first appeared about two million years before the arrival of humans.

The drying up of the land Much of the world was shrouded in ice at various times during the Pleistocene, and during these Ice Ages temperatures everywhere fell, evaporation of the seas and lakes diminished, and so less rain fell. Other factors contributed to an increasing aridity, and by 30 000 years ago much of inland Australia had changed from lush rainforest to grassland and dry, open forest, followed later by the sandy deserts and salt lakes of the present day. The animals reacted to the drying up of the land in three different ways: some became extinct, some developed adaptations to the increasing aridity and were able to survive, and some continued to live in the higher, wetter and cooler highlands of eastern Australia and New Guinea. The wombats did all three. The giant wombats became extinct, along with most of the rest of the megafauna – the diprotodons and marsupial lions, the giant kangaroos and other outsize marsupials. One of the most intensely cold and dry phases of the Pleistocene occurred between 25 000 and 15 000 years ago, and it was during this time that most of the giant mammals disappeared from the scene. Hunting and firing of the land by the Aborigines may also have contributed to their extinction. A species of wombat closely related and similar in size to the modern bare-nosed wombat, Vombatus ursinus, also became extinct during the late Pleistocene. Fossil remains of this species, Vombatus hacketti, have been found in the Mammoth Cave and Devil’s Lair deposits in south-western Western Australia. The hairy-nosed wombats adapted to the increasing dryness, and their modern descendants live successfully in such semi-arid areas as the Nullarbor Plain. The bare-nosed wombats, on the other hand, sought refuge in the cooler forests of the south-east. The common wombat, which is now the only surviving member of the genus Vombatus, needs the more temperate climate 4

Evolution and early history

Figure 1.4 A mountain valley in the New South Wales high country (left) and a dry sclerophyll forest (right) – favoured habitats of the bare-nosed wombat.

and moister habitat found in these forests (Figure 1.4). It would be unable to survive if exposed to the harsh way of life of its hairy-nosed relatives. The name ‘common wombat’ is misleading; this species is no longer common and its range is declining rapidly. Therefore I have chosen to use another of its names – bare-nosed wombat – for the remainder of this book. For the next 10 000 years or so all the ‘modern’ wombats flourished in their various chosen habitats. Although it is likely that they were hunted sporadically by the Aborigines for food, they were fortunate in that other animals, such as kangaroos and wallabies, were also present and easy to hunt, and that other small marsupials provided warmer furs. We may tend to think of Aborigines as desert people who wore very little, if any, clothing; but until Europeans arrived in this country, many Aborigines lived in the coastal areas and in the south of the continent where the chilly temperatures would make some kind of body covering most desirable. The skins of possums were the ones most commonly used by Aboriginal people as clothing, but wombat fur was used to make string. About 4000 years ago, the dingo arrived in Australia. We do not know whether it was brought in by immigrant Aborigines or came unaccompanied, 5

Wombats

but what is certain is that this efficient and specialised Asian predator had a lamentable effect on the marsupial fauna of mainland Australia. In particular, it is believed to have contributed to the annihilation of the thylacine on the mainland, partly by direct predation and partly by competition for food. By the time Captain Cook arrived in 1770 this, the largest surviving marsupial carnivore, was confined to Tasmania. The dingo never reached Tasmania because the rising sea-level at the end of the last Ice Age, which caused the separation of Tasmania from the mainland, occurred about 12 000 years ago, before the dingo’s arrival. For wombats the arrival on the scene of this efficient hunter probably made little difference; undoubtedly the thylacine would have preyed on wombats, especially the very young and the very old, in just the same way as the dingo did, and still does today. The defensive tactics used against the thylacine would have been fairly effective against the dingo also, so the wombat simply exchanged one enemy for another as the dingo gradually replaced the thylacine.

Modern wombats Only three species of wombat survived the Pleistocene to modern times, i.e. the last 10 000 years. These three modern species were probably quite widely distributed at the time of European settlement, 200 years ago, but reliable records are few. The southern hairy-nosed wombat (Lasiorhinus latifrons) (Figure 1.5a and Plate 2) was then distributed from the eastern corner of Western Australia across South Australia to the Murray River. Its close relative, the northern hairy-nosed wombat (Lasiorhinus krefftii) (Figure 1.5b and Plate 1) was still present in northern Victoria and southern New South Wales as well as in south-eastern Queensland, but fossil records show that it had been much more widespread during the late Pleistocene. The bare-nosed wombat (Vombatus ursinus) (Figure 1.5c and Plate 3) occupied a stretch of country from south-eastern Queensland, through New South Wales along the Great Dividing Range and associated ranges to Victoria, where it was spread over most of the state except the northwestern corner. It was also present in the south-east of South Australia, in Tasmania and on many of the larger Bass Strait Islands. It has been said that the first thing Captain Cook did when he sighted a kangaroo in 1770 was to ‘set the dog on to it’. Almost the first thing that Europeans did when they sighted a wombat in 1797 was to eat it, but perhaps they can be forgiven as their need for fresh meat was probably 6

Evolution and early history

(a)

(b)

(c)

Figure 1.5 The three species of wombat: (a) southern hairy-nosed wombat (Photo: (b) northern hairy-nosed wombat (Photo: A Horsup) , and (c) bare-nosed wombat.

C Marks) ,

7

Wombats

great. Sailors from the Sydney Cove, shipwrecked on Preservation Island in the Furneaux Group in Bass Strait, kept themselves alive on a diet that included wombat as a major feature. These sailors were eventually rescued after a year on the island, and Matthew Flinders, who accompanied the rescue party, took a live wombat back to Sydney Town and presented it to Governor Hunter. This wombat lived for only six weeks, but Hunter had it preserved in spirits and sent to Sir Joseph Banks in London with a letter that included the following remarks: It is about the size of a badger, a species of which we supposed it to be, from its dexterity of burrowing in the earth, by means of its forepaws; but on watching its general motions, it appeared to have much of the habits and manner of a bear … This animal has lately been discovered to be an inhabitant of the interior of this country also … The mountain natives call it Wombach. The discovery mentioned by Hunter had been made in January 1798 by a former convict, James Wilson, and one of Hunter’s servants, John Price, who accompanied Wilson on an expedition into the Blue Mountains west of Sydney. Price reported: We saw several sorts of dung of different animals, one of which Wilson called a Whom-batt, which is an animal about 20 inches high, with short legs and a thick body with a large head, round ears, and very small eyes, is very fat and has much the appearance of a badger. This was the first description of a wombat by a European, and it seems extraordinary that our early settlers had been in the colony for 10 years before recording one. Wombats had, however, long ago adopted a seminocturnal existence, and the early colonists had little incentive or, in the case of convicts, little opportunity to wander at night in this unfamiliar land of shrieking possums, hostile natives and other unknown hazards. At first, the discovery of Australia’s strange and exotic animals caused a flurry of interest, and many specimens were sent back to England for the zoologists to examine. But for the colonists, life was a grim battle as they set about the task of clearing the land for crops and for better pastures for their sheep and cattle, and they had little time to be sentimental about the animals whose land they were altering so irrevocably. Although they 8

Evolution and early history

found that some were edible – wombat hams and kangaroo steaks often supplemented scanty food supplies – and that many provided skins which could be sold or used for rugs and clothing, they generally thought of all the native animals as pests. ‘If it moves, shoot it’ seems to have been the general rule. The southern hairy-nosed wombat was not discovered until the middle of the 19th century, when colonies were found in South Australia west of the Murray River. It had been described from a skull in 1845 by Richard Owen, a British researcher who in 1872 also described the northern hairynosed wombat from a skull sent to him by a German zoologist, Johann Krefft, who collected it, along with other fossils, from the Wellington Caves in New South Wales in 1869. It was not until 1884 that northern hairy-nosed wombats were found living at Moonie River near St George in southern Queensland and in southern New South Wales near Deniliquin. These populations became extinct early in the 20th century, but a population was found in 1937 in central Queensland near Clermont on a cattle property called Epping Forest Station.

Classification Wombats have been likened to badgers, bears, beavers, even pigs; but although there are some similarities of appearance and habits, there is no relationship between the wombat and any of these animals except that they are all mammals. The wombat is a marsupial, whose tiny embryonic young are born after only about 30 days in the uterus of the mother and then spend about eight months in her pouch. The badger, bear, beaver and pig on the other hand are all placental mammals, whose young develop in the uterus of the mother for several months before their birth at a relatively advanced stage of development. The marsupials are divided into four major groups, or Orders. The wombats belong to the Order Diprotodonta. All the members of this order have only two incisor teeth in the bottom jaw, these teeth pointing forward almost horizontally, and syndactyl toes on the hind foot – a condition in which the second and third digits are partly fused together. Koalas and wombats have enough similarities to one another to be placed in the same Superfamily, the Vombatoidea. These similarities include: their tails, which are very short and rudimentary; their pouches, which open towards the rear; their stomachs, which are very small and 9

Wombats

Table 1.1 Classification of the wombat family and its relationship to the koala PHYLUM

Chordata

SUBPHYLUM

Vertebrata

CLASS

Mammalia

SUBCLASS

Marsupialia

ORDER

Diprotodonta

SUPERFAMILY

Vombatoidea

FAMILY

Vombatidae

Phascolarctidae

GENUS

Vombatus

Lasiorhinus

SPECIES

ursinus

latifrons

krefftii

cinereus

Bare-nosed wombat

Southern hairynosed wombat

Northern hairynosed wombat

Koala

COMMON NAME

Phascolarctos

have a specialised gastric gland, and their sperm, which are very similar in shape but unlike those of any other marsupial. Experiments with blood serum of the wombats and the koala have shown that they are possibly closely related, and it is thought that they probably shared a common ancestor about 25 million years ago. The full classification of the wombat and its relationship to the koala is shown in Table 1.1.

Wombat distribution today Just over 220 years have now passed since the settlement began at Sydney Cove, which is a moment in time as far as the wombat is concerned, but during those years the face of Australia has been profoundly changed. One of the results of the European occupation of the land is clearly demonstrated 10

Evolution and early history

(a) (b)

(c)

Figure 1.6 Present distribution of wombats. (a) Northern hairy-nosed wombats are now found only at Epping Forest in Queensland. Two populations near St George probably became extinct early last century. Data source: Crossman (1988) (b) The southern hairy-nosed wombat is found in South Australia with a few small colonies also found in south-western Western Australia. Data source: St John (1998) (c) The approximate range of the bare-nosed wombat. It occurs only in some areas of suitable habitat, avoiding rainforest, for example. Data sources: ‘Atlas of Victorian Wildlife’, © The State of Victoria, Department of Sustainability and Environment; Atlas of NSW Wildlife, NSW Department of Environment and Climate Change; Department of Primary Industries and Water, Tasmania; K. Mallet and B. Cooke in The Ecology of the Common Wombat in South Australia.

11

Wombats

by the shrinking of the range of all three wombat species. The northern hairy-nosed wombat is one of Australia’s rarest mammals, with only about 135–140 individuals surviving in the last known colony in central Queensland. This colony is confined to the Epping Forest National Park, 120 kilometres north-west of Clermont in central Queensland (Figure 1.6a). The southern hairy-nosed wombat is now confined to four main population centres – the Nullarbor Plain, the Eyre Peninsula, the Gawler Ranges and the Murraylands. There are also a few isolated colonies on the Yorke Peninsula (Figure 1.6b). The bare-nosed wombat has fared a little better, but it has now almost disappeared from the western half of Victoria and it is absent from all but two of the Bass Strait Islands as well as from many parts of New South Wales where it formerly ranged (Figure 1.6c). It has also declined in South Australia. Brian Cooke has investigated this decline and has found that it was probably caused by rabbits. Native pastures were altered to such an extent by these pests that wombats could no longer maintain populations, except in the most favoured parts of their former range. The effect on the wombat of the changes made in the last 200 years, and the impact of Europeans in general, more correctly fall under the heading of ‘Disasters’, so we will leave them for another chapter.

12

2 THE WOMBAT ITSELF

W

ombats are grazing animals and are among the world’s largest burrowers. Many of their physical characteristics reflect these two habits.

Body shape and size Their thick-set, low-slung bodies vary in size according to where they live and there is some variation between the three species. Bare-nosed wombat adults on mainland Australia are usually about a metre long, measured from nose to tail, and they stand about 25 centimetres high at the shoulder. The average weight of mainland wombats is about 26 kilograms, but weights of 35 kilograms are not uncommon. Tasmanian wombats are slightly smaller. Robert Green and John Rainbird measured the body lengths and weights of a sample of 291 Tasmanian mainland wombats and found that the average length was about 81 centimetres and the average weight about 19.5 kilograms. In a similar study they found that the Flinders Island wombats are slightly smaller and lighter – about 78 centimetres long and 17.6 kilograms in weight. 13

Wombats

Northern hairy-nosed wombat adults are also about a metre long and weigh from 30–32.5 kilograms, but the southern hairy-nosed wombats are smaller. Adults of this species are, on average, about 85 centimetres long and weigh about 25 kilograms. The wombat’s head is set squarely on a short, strong neck. The stocky, barrel-shaped body ends in a very small bare tail, which in an adult is completely hidden by fur. The powerful shoulders and broad pelvis reflect the wombat’s burrowing habits, which are also catered for by its amazing ability to flatten out its chunky body when lying prone. I have seen an adult wombat, 24 centimetres tall at the shoulders, squeeze itself through a gap only 10 centimetres high, with little apparent effort.

Coat and skin There is much variation in the colour of bare-nosed wombats. Glossy black, dark grey, silver-grey, chocolate brown, grey-brown, sandy and creamcoloured wombats are all found. (Plates 4 and 7). A small colony of ash-white wombats, with dark eyes and pale yellow markings on the face, is found on Wilson’s Promontory in southern Victoria (Plate 5). Albino wombats also have occasionally been reported. It is not uncommon for black wombats, in particular, to have one or more patches of white fur and, occasionally, white claws, but most wombats are uniformly coloured. Frequently a wombat will appear to have patches of fur that are lighter in colour than the rest of the coat, giving rise to descriptions such as ‘motheaten’ or even ‘spotted’. When new fur grows over a healed wound, it is usually much lighter in colour than the rest of the coat, and it is this new hair which gives the wombat a temporarily patchy appearance. A wombat’s coat can also be coloured by the soil in its locality, particularly that in the burrows. Clay, for instance, can stain the fur red (Plate 6) and dark, loamy soil colours it black. Several different colours of bare-nosed wombats may be found in the same area, but one colour usually predominates. In most parts of the eastern ranges in Victoria, the principal colour is grizzled brown, while in some coastal areas and in Tasmania, the majority of the wombats are grey. The hairs of a wombat’s coat are a mixture of several colours, but the overall colour of an individual depends on the amount of each colour in the blend. A brown wombat, for instance, has intermingled black, brown and gold hairs, and some of these hairs have white bands, but the dominant colour is brown. 14

The wombat itself

The texture of the coat of the bare-nosed wombat is generally coarse; the long guard hairs are about 200 microns in diameter, which is nearly twice the diameter of the coarsest human hair. The hairs on the wombat’s rump are particularly coarse and are better described as bristles. These are only about one or two centimetres long, in contrast to the hairs on the flanks and shoulders, which are up to six centimetres long. Northern hairy-nosed wombats have soft fur, about 100 microns wide. The usual colour is grey-brown, but some wombats have grey fur mottled with black, dark brown or a sandy brown colour. Most of the hairs are about 3.5 centimetres long. The southerns also have silky fur, about 125 microns wide. It is light to dark grey, darkest above the forequarters and slightly longer than the northerns – about 4.5 centimetres. All wombats have a very thick skin, especially on the back and rump. The layer covering the strong, broad pelvis is about one centimetre thick, and it gives the wombat considerable protection against the bites of enemies such as dogs and dingoes. If a wombat is chased into a burrow, it will wedge its strong back against the roof of the burrow to block it; there have been a number of instances where a wombat is known to have crushed a dog’s skull against the roof of a burrow, and others are probably killed by suffocation as they are squeezed against the burrow walls.

Head and face The wombat’s broad massive head seems almost too large for the stumpy body, but it is marvellously adapted for its purposes. The bones of the skull are extremely strong and unlikely to be damaged when the head is used, as it often is, as a battering ram to move comparatively large and heavy objects. A stubborn rock or stone encountered while digging a burrow, a newly fallen tree branch or a small sapling encroaching on a favourite pathway, a tautly strung wire fence – the wombat simply pushes at them with its broad strong head, and with its not inconsiderable weight and stubborn nature, it usually succeeds in moving the object aside or lifting it out of the way. The top of the wombat’s skull is also broad, and the bones that, fused together, form the cranium or brain case are particularly strong and rigid. The skulls of the two genera of wombats have significant differences, which makes them easy to tell apart. For example, the zygomatic process (the projection on the cheek-bone) is much larger in the hairy-nosed wombat (Figure 2.1). 15

Wombats

Figure 2.1 Skulls of the southern hairy-nosed wombat (left) and bare-nosed wombat (right). The zygomatic process (the projection over the eye socket) is much sharper and the nasal bones are much wider in the hairy-nosed wombat.

The wombat’s rather heavy face is adorned by a luxuriant set of long sensitive whiskers growing on the muzzle, and by four other smaller sets: one above the eyes, one on the cheeks, one under the chin and one near the throat (Figure 2.2). The dark brown eyes are small and set towards the side of the head, a useful feature when the wombat is digging; it also makes them less susceptible to injury when the animal is passing through the undergrowth. The eyelids are fleshy, with only a few short eyelashes. The eyesight itself appears to be poor; as the wombat spends the greater part of its life in the dark, either underground or abroad at night, other senses are more important than good eyesight. The erect ears are small, well-furred with rounded tips in the barenosed wombat but narrower, sparsely furred with pointed tips in the hairynosed wombats. The ears are set sideways on the head and they collect sounds very efficiently but can be rotated only slightly towards the back and the front as an aid in sound location. A wombat cannot flick its ears through 180 degrees as a kangaroo can, but has to turn its whole head from side to side to pinpoint the direction of a sound. 16

The wombat itself

Figure 2.2 The bare-nosed wombat (left) and southern hairy-nosed wombat (right).

The wombat’s large nose is the most prominent facial feature. The nose of the bare-nosed wombat has a covering of thick, bare skin, which is normally ‘dry’, in contrast to that of a dog, where a dry nose indicates ill-health. This is in contrast to its hairy-nosed relatives, who have soft muzzles with a covering of silky white fur between the nostrils. The openings of the nostrils are extremely large, as are the nasal passages. The olfactory system is very sensitive, and the wombat probably relies even more on its excellent sense of smell than on its sense of hearing. Both the upper and lower lips are fleshy and mobile, the upper lip particularly so, and the cleft in its centre gives an even greater mobility, which is very useful when the animal is selecting grass stems. In common with all the other members of its order, the Diprotodonta, the wombat has only two lower incisor teeth, but it is the only marsupial to have only two incisors in the upper jaw also. There is a large gap, called the diastema, between the incisors and the rest of the teeth, which consist of one premolar and four molars on each side of each jaw (Figure 2.3). The wombat’s teeth are unique in that both the incisors and the molars are rootless and continue to grow throughout the animal’s life. Rodents – rats, mice and so on – also have continuously growing incisors, but their molars have permanent roots. 17

Wombats

Figure 2.3 Underside of the bare-nosed wombat’s skull (left). Notice the long gap, the diastema, between the incisors and the cheek teeth. The lower jaw (right) also has a long diastema. Notice the chisel-like incisors.

The wombat’s upper molars curve outwards and the lower molars curve inwards. When it is chewing its food the lower jaw moves sideways and upwards so that the blades of the two sets of molars meet, cutting the grass stems.

Legs and feet Although the wombat’s legs are very short, they are ideally equipped, not only for carrying the heavy body but also for digging. The feet are plantigrade (‘sole-walking’): the animal walks with the entire sole of its foot on the ground. This is a characteristic of animals that mostly walk and seldom run, whereas the runners, such as the carnivores, walk on the ball of the foot and have digitigrade (‘finger-walking’) feet. The wombat’s front feet are broad and have five toes with long strong claws, blunted at the tips by digging. The hind feet are longer and narrower; only four of the toes have long sickle-shaped claws. The first, or inner, toe is a clawless nub, and it can be seen from the skeleton of the wombat that the bones of the second and

18

The wombat itself

Figure 2.4 The broad front foot with five strong claws (left) and the hind foot (right). The inner toe of the hind foot is a clawless nub, but the other toes have long claws. Illustrations: © Jonathan Guy

third toes of the hind foot are fused together, as in all other diprotodont marsupials, but this join is not as obvious in the living animal as it is, for instance, in a possum, koala or kangaroo (Figure 2.4). The soles of both the front and hind feet have fleshy pads, covered in tough, leathery skin which becomes roughened with age and wear. When a wombat first emerges from the pouch this skin is pink and soft, but it soon becomes black and leathery.

Sexual characteristics There are no obvious distinguishing marks between the sexes of wombats. In the few studies that have been done, it has been shown that females tend to be slightly larger than males of the same age, but there is so much variation in size and weight in different localities that it is not possible to generalise. As in all male marsupials, the penis is stored within the body, not carried externally as it is in placental mammals. It is about 12–15 centimetres long when erect and it is retracted into the body in an S-shaped curve when not erect. The testes are carried in a heart-shaped scrotum, suspended by a very short stalk from the lower part of the belly. The female’s pouch contains two teats, both near the posterior end of the inner pouch wall. In an immature female or an adult that has not yet carried pouch young, the teats are small and recessed in a circular fold of skin, forming a kind of pocket, but they become gradually elongated during lactation and eventually may even protrude beyond the pouch

19

Wombats

opening. The inside of the pouch is almost hairless and the pink skin is slightly moist. A strong sphincter muscle controls the opening, keeping the pouch free of dirt while the wombat is digging and also when she is moving about in the narrow, dusty tunnels of her burrows.

20

3 BURROWS

Bare-nosed wombat burrows One of the earliest and most interesting studies of wombats and their burrows was made in 1960 by a schoolboy, Peter Nicholson, who was then a student at Timbertop, the country branch of Geelong Grammar School. This school is situated in the foothills of the Great Dividing Range in north-eastern Victoria, and it was in these forested hills, between 500 metres and 1300 metres above sea-level, that Nicholson made his subterranean explorations of bare-nosed wombat burrows. Armed with a torch, a mattock and spade, and half a kerosene tin for his booty, he crawled along the narrow tunnels, sieving the floor dirt to remove any bones he found there. He eventually amassed enough to assemble a complete wombat skeleton. Nicholson also mapped several burrows by driving pegs into their floors and stretching cords between the pegs. He drew a plan of one of the larger burrows he explored, and he also made many interesting observations of the wombats themselves. The written account of his wombat study, which was entered for a students’ science competition and later published 21

Wombats

in the school magazine, is still one of the most useful in-depth studies of wombats that has been published. In 1968 John McIlroy, of the CSIRO Division of Wildlife and Ecology in Canberra, began a three year study of the ecology of the bare-nosed wombat. McIlroy, being larger, older and not as adventurous as Nicholson, did most of his investigations of burrows from the outside, although he did crawl up to three metres inside some of the larger burrows. With the aid of a torch and a flexible pole three metres long, or, for longer burrows, a plumber’s ‘snake’ (a long flexible steel cable used for clearing drains and sewers), McIlroy examined 197 burrows. He classified them into three groups, according to their length: minor burrows, only about 1–1.5 metres long; medium burrows, 1.5–5 metres long; and major burrows, more than five metres long. Smoke was forced down burrows to determine whether there were inter-burrow connections or whether the burrows had only single entrances. He also located wombats’ positions in their burrows by radio-tracking, and during another study, in 1979, he excavated seven wombat burrows and took their internal measurements. Typical burrows From Peter Nicholson’s account and John McIlroy’s detailed research into all aspects of burrows, as well as some observations of my own, some general conclusions about bare-nosed wombat burrows can be drawn. A typical major burrow, one that has been used by many generations of wombats, has a large mound of soil outside the entrance. This soil, loosened during the excavation of the burrow and during many renovations and extensions since, often occupies a considerable area, usually about 2.5 square metres but often as large as eight square metres. A medium burrow has a smaller mound, but it is still conspicuous; a small overgrown mound is sometimes all that remains at a minor burrow. At a freshly dug burrow, or one recently cleaned out or extended, the soil is still loose and fresh. It gradually becomes compacted over the years, and the mound may be eroded away. Much of it is subsoil such as clay, and this, as well as the regular use of the burrow by heavy-footed wombats, often prevents the mound of a major burrow from becoming overgrown. Signs that a burrow has been recently occupied are frequently seen on or near the mound. These signs include tracks and scats (i.e. faeces) and also the scratch marks made by the wombat’s strong claws (Figure 3.1). In the vicinity of a major or a medium burrow there is often a patch of flattened vegetation or a small excavation, a sit, flattened or worn smooth 22

Burrows

Figure 3.1 The large mound of loose soil outside this burrow shows evidence of recent activity, including scats and scratch marks. Photo: L Trewenack

Figure 3.2 This burrow entrance is partly supported by a large horizontally growing root. Notice the bitten ends of roots and stalks around the entrance.

23

Wombats

Figure 3.3 Diagrammatic cross-section of a typical medium or major burrow excavated into a slope. Redrawn from McIlroy (1972)

by many wombat bodies, for they sometimes leave their burrows to drowse in a sheltered spot in cool to mild weather, particularly on overcast days. All the sits I have found have been in shaded positions, but other observers have recorded wombats spending some time in their sits basking in the morning or late afternoon sun. The sit is also often used when a wombat leaves the burrow in the evening; before setting out on a foraging expedition, it will pause at the sit, sampling the air for scents and sounds. The entrance of a well-established major burrow is well-worn and often very large – sometimes large enough for a man to crawl through easily – and both major and medium burrow entrances are generally at least half a metre high and nearly as wide. The entrance is usually single and either oval or shaped like an inverted U. Frequently, some of the roots from nearby trees or other plants help to support the entrance, while the broken ends of other roots that have been bitten through or scratched away are visible (Figure 3.2). The entrances to minor burrows are small, and some are too small for a bulky adult wombat to enter. Many major and medium burrows are dug on sloping ground – the steeper the slope the less danger there is of flooding from surface run-off from the slope above – and they usually extend horizontally into the sloping bank or hillside (Figure 3.3). Some major and medium burrows and many minor burrows are dug on flat or weakly sloping ground, and these usually descend steeply at first, for a distance of 0.5–5 metres from the entrance (Figure 3.4). Both types of tunnels, those on slopes and those on flat ground, then either continue on in a straight line or may change direction a number of times, turning and twisting abruptly. They may gradually slope upward or 24

Burrows

Figure 3.4 Diagrammatic cross-section of a typical minor burrow in flat ground, descending steeply for the first 0.5–1 metre before levelling off and ending abruptly without a bedding chamber. Redrawn from McIlroy (1972)

downward, and the tunnels also often rise and fall slightly, forming small humps and hollows. Some of these hollows are enlarged by the wombat into oval chambers, which vary considerably in size – on average they are about one metre long and 0.5 metre wide – and these may be used as resting chambers. Most major and medium burrows have at least one or two resting chambers, which may be either unlined or lined with vegetation. McIlroy found that this bedding material usually consists of bracken fronds, eucalypt leaves and twigs, strips of bark, and sometimes small tussocks of Poa grass and the leaves of other plants. I have watched a wombat biting through the stems of several fronds of cartilage fern (Blechnum cartilagineum) which grew near her burrow. She then walked backwards towards the burrow and then into it, continually raking the fronds towards her chest with her front paws. Leafy twigs are probably taken into burrows in the same way, but some of the leaves and twigs that are found in burrows may have been blown in or dragged in accidentally by the wombat’s feet and later scratched into the resting hollows. Apart from leaves and twigs and other vegetation, the floor of a wombat burrow is clean and, in dry weather, dusty. Scats, either old or fresh, are not found in any part of the burrow. Burrow networks Sometimes a major burrow forks into two or more tunnels, and these tunnels may link up with others, either from the same burrow or from adjacent burrows, forming a network of interconnecting tunnels and entrances. McIlroy radio-located a wombat in a complex burrow system with three entrances that connected underground (Figure 3.5). The tunnels leading from these entrances appeared to be longer than the distance that could be 25

Wombats

Figure 3.5 Probable plan of a burrow system described in the text.

Redrawn from McIlroy

(1972)

measured with a plumber’s ‘snake’. As the wombat was located 11 metres directly in from the entrance of the middle burrow, which was a greater distance than the recorded lengths of the tunnels, it was probable that the burrow system was very long indeed, as is shown in the scaled plan. Other very long burrows have been measured. Finlayson recorded an attempt to dig out a wombat that had to be abandoned when he had reached a distance of 10.2 metres in from the entrance and 1.8 metres below the surface, and Troughton referred to burrows explored by the ‘open cut’ method that were up to about 30 metres long. Peter Nicholson also measured burrows up to 18 metres long, not counting the network of tunnels. Complex burrows form over long periods, and they are usually found only where burrows are clustered together because there is a limited area of favourable ground available for digging. Where there is ample suitable ground wombats space their burrows much more widely apart, and there is little chance of their becoming interconnected. Siting a burrow The sloping sides of hills, especially forested slopes above gullies and creeks, are the most favoured locations for burrows. Along these slopes, 26

Burrows

Figure 3.6 A fallen tree provides the entrance to this burrow.

Figure 3.7 A burrow site under large boulders.

27

Photo: M Schulz

Wombats

wombats seem to prefer to dig in places where the earth has been exposed, such as under the bases of fallen or standing trees (Figure 3.6) or under rocky outcrops (Figure 3.7). They tend to exploit natural weaknesses, where excavation is easier, and in rocky, mountainous country many burrows are located beneath the rocks and boulders. Not all burrows are dug into slopes, and by no means all become major burrows. A wombat will scratch out the beginnings of a burrow almost anywhere. Many burrows, begun in unsuitable places – such as creek beds and hollows, on the lower banks of creeks, rivers and swamps, and on flat ground, all of which are susceptible to flooding – will be abandoned before they are one to two metres long. These minor burrows are rarely used by the wombat, except perhaps as a temporary shelter in an emergency. Often they become overgrown, as a horseman has occasionally found to his sorrow. Rabbits sometimes take them over and extend them for their own purposes. Sometimes a burrow may be begun where all the conditions are favourable but still be deserted by its originator for some reason – perhaps because it died or left the area. This minor burrow may be reworked later on by another wombat and gradually extend to the status of a medium burrow, and after an even longer period, may become a major burrow. Most of the longer burrows (15 metres or more) are probably the work of several wombats, although occasionally a single wombat can, by excavating furiously, construct a major burrow in a short time. One wombat I observed dug a burrow more than six metres long in less than a week. Digging into the vertical sandy bank of a dry swamp, he progressed at the rate of about two metres a night. Usually he dug for only an hour or so at a time, emerging to feed in the vicinity of the excavation before returning to it for another bout of digging. When the burrow reached a length of six metres it changed direction, and I was unable to measure it further; but judging by the vast amounts of sandy soil that were regularly ejected from the burrow for the next 10 nights, it was considerably larger by the time he ceased his digging operations. On other occasions when I have watched wombats digging in harder ground, the going was slower. A young semi-tame wombat watched by McIlroy dug at the rate of one metre per night. Burrow occupancy A burrow is not the exclusive property of any individual bare-nosed wombat; a major burrow may be used by several different wombats, but

28

Burrows

usually at different times – an arrangement that can be compared with the ‘time-share’ system now in vogue among users of holiday flats and homes. Sometimes ‘double-bookings’ occur, and a wombat will enter a burrow that is already occupied by another. Usually this is tolerated, but occasionally one may be chased out – an immature wombat by an adult, for instance. There is some limited evidence that adult females, around the time of gestation and with very small pouch young, may have a preference for a particular burrow and maintain exclusive use of it for a period. This may also occur when the young wombat first begins to emerge from the pouch (see Chapter 6).

Hairy-nosed wombat burrows Ten burrows of the southern hairy-nosed wombat were excavated by Vernon Steele and David Temple-Smith in order to examine their structure, but a different method was used to study the burrows of both species of hairy-nosed wombats by Glen Shimmin and his colleagues. They sank narrow boreholes from the surface to penetrate the roof of the burrow. These boreholes were lined with plastic pipe and a video camera with a light source was lowered down the pipe. This enabled them to view the structure of the burrow and any wombats that might be in that area and to decide where to place the next borehole. In this way the whole burrow was mapped (Figure 3.8). Typical burrows Southern hairy-nosed wombat burrows vary greatly in length. The burrows and warrens excavated by Steele and Temple-Smith ranged from 1.5 to 61.2 metres, and had one or two entrances. They found another warren with 10 entrances. Their research also showed that in some burrows the wombats had built plugs of earth which blocked the tunnel they occupied, probably as a defensive measure. Glen Shimmin’s work showed that many hairy-nosed wombat burrows have only one entrance and range in length from four to 28 metres. They are dug on flat ground and begin with an entrance crater which leads into one or more tunnels. The southern hairy-nosed wombats also have more complex burrows which form large warrens. The largest one they found had 28 entrances and a total length of 89 metres, on several levels. The tunnels were between one and two metres deep. Northerns also form

29

Wombats

Figure 3.8 The plan (top) and section (bottom) of a large burrow complex of the southern hairy-nosed wombat, showing how portholes were used to map the burrow. Redrawn from Shimmin et al. (2002)

warrens but they are generally simpler. Shimmin found one warren with three entrances and a tunnel length of 54 metres, but most had only one entrance and an average length of about 12 metres. They were deeper than the southerns’ burrows – up to four metres deep. Major ‘core’ burrows have up to 12 entrances, although the average is two to three entrances. There has been a 40% increase in the number of burrows in the last three to four years, which is good news for this endangered species. Most of these new burrows have only one to two entrances but there are signs that they are expanding in size. All of the currently active burrows of the northern hairy-nosed wombat are found along the remains of an old watercourse. Burrow networks A southern hairy-nosed wombat’s warren has many entrances and the burrows are interconnected. Around the warren there is a circle of small burrows with single entrances. These are about 100 metres from the central warren. Burrows of the northerns are arranged in groups that are used by four or five wombats. Well-worn paths lead to these burrows, which may have several entrances.

30

Burrows

Siting a burrow Both species of hairy-nosed wombats choose flat ground for their burrows. The southerns seem to prefer grassland to scrub as the site for their warrens. In many parts of their range there is only a thin layer of soil covering a limestone shelf, which in turn covers a softer strata. The wombats have found weak points in the limestone and dug through to the softer ground beneath, using the shelf as a roof (see Plate 8). In other areas where there are deep clay soils the burrows are prone to collapse after heavy rainfall. Most of the northerns’ burrows are in or adjacent to sandy gullies, where the sand is soft and deep (see Plate 9). They are often close to trees, which provide shade as well as support by their roots in the soft, sandy ground. Burrow occupancy Warrens of the southern hairy-nosed wombats can be shared by up to 10 wombats, who graze the area around the warren as far as the smaller, perimeter burrows. This grazed area forms a halo of cropped grass, about four hectares in area. The perimeter burrows are used as temporary refuges by the grazing wombats and are also used by young wombats who have been driven out of the warren. Johnson and Crossman used telemetry to follow the movements of 28 adult northern hairy-nosed wombats. They found that most burrows of the northerns are occupied by a single wombat about 70% of the time. Some burrow sharing occurs in the multi-entrance burrows, usually between females only.

Digging a burrow An adult wombat, with a number of well-established burrows, probably rarely initiates a new burrow, although it frequently extends and renovates existing ones. A young wombat, however, particularly one that has recently become independent of its mother, will often appear to be deliberately seeking out a place to begin a burrow, pausing frequently in its grazing to investigate exposed ground at the bases of trees and rocks, weaknesses under large exposed tree roots, butts of fallen trees, root holes where trees have burnt out either completely or partially, and similar places. A few exploratory scratches with the front paws are enough to indicate to the wombat whether or not the site has possibilities,

31

Wombats

and it will then either move off to look for another site or settle down to digging in earnest. Standing with the back legs firmly braced, the wombat begins to dig with its front paws, scratching with one paw for a few moments and then the other (Figure 3.9a). As the strong, spade-like claws loosen the soil, the broad palms scoop it up and thrust it out sideways and backwards (see Plate 10). Any grass or other vegetation encroaching on the opening is bitten off and eaten if edible or cast aside if not. If a root, large or small, is uncovered, it is gripped in the teeth and either bitten off or pulled free, and obstinate stones or lumps of hard-packed soil or clay are often bitten in attempts to free them from the surrounding soil. When some loosened soil has accumulated the back legs are brought into play, vigorously kicking and pushing the soil backward. After more energetic scratching with the front paws and backward thrusting with the back ones, the wombat will move backwards slowly, using all its paws to push the loose soil behind it, away from the digging site, often pausing to kick with the back legs (see Plate 11). In this way it gradually produces a kind of ramp, an entry-way that slopes up to the mound of soil that accumulates at the top of it. After about 20 minutes of concentrated digging, the wombat usually sits down on the ramp for a short rest, often scratching an ear and shaking its head vigorously to free it of dust and dirt before resuming digging activities. In this way a hole is created in a very short time. To enlarge it, the wombat will frequently lie partly on its side, legs still braced (Figure 3.9b), or even completely on its side, scratching at the walls and roof of the tunnel, before standing again to eject the soil (Figure 3.9c). A wombat will dig into most kinds of soils, sand or clay, according to the prevailing conditions in the district. In some areas burrows are even dug in gravelly, stony ground. The slope of the ground and the resulting drainage conditions probably influence the wombat’s choice of a burrow site, but the most important factor in this choice appears to be the presence of natural weaknesses in the ground.

Danger of flooding Flooding is probably the most common calamity that befalls wombat burrows; all of those dug on flat ground may be subject to it, and even where the ground is sloping and the drainage is good, some water usually gathers near the entrance after heavy rain. Following one very long wet 32

Burrows

(a)

(b)

(c)

Figure 3.9 (a) The spade-like front claws thrust the soil backward, and the roots are pulled free or bitten off. (b) The wombat may lie partly on its side, legs still braced, scratching at the walls of the tunnel before (c) standing to eject the loosened soil.

33

Wombats

spell, all but one of the seven burrows I was studying at the time had some water in them; two, on the lower bank of a creek were impassable, but others were still in use although water was in their entrance tunnels. Presumably these tunnels slanted upwards sufficiently to prevent the water from reaching the sleeping chambers. As soon as the water had seeped away there was an orgy of house-cleaning, as mud, sodden dead leaves, bark and fern fronds were scratched up and kicked out of most of the burrows that were in use at the time.

Other occupants of burrows Other animals may live in the same burrows as wombats. Rabbits sometimes dig their own smaller side tunnels in medium and major burrows occupied by wombats, and I have seen dusky antechinus emerging from small crevices in the walls of bare-nosed wombat burrows and the smaller brown antechinus and bush rats scurrying away from burrow entrances. Wild dogs and foxes sometimes occupy wombat burrows; while foxes are sometimes tolerated, they are generally disliked by wombats. Crushed skulls of foxes and dogs have been found in burrows, evidence of the wombat’s well-known method of disposing of intruders, and I have seen a fox chased out of a burrow by an angry adult wombat. Other animals that have been reported in bare-nosed wombat burrows include echidnas, brushtail possums and cats. Rabbits have also been found in southerns’ burrows, as well as geckos and stumpy-tailed lizards. The burrows of the northerns also have other occasional inhabitants, including dingoes, cats, echidnas, rufous bettongs and swamp wallabies. Goannas and pythons have also been found in wombat burrows. However, apart from these infrequent invasions, the wombat’s burrow is a secure haven. It is easily defended against predators, gives protection from bushfires and other hazards and provides a cool, comfortable environment for the wombat’s long day’s rest.

34

4 WHAT GOES ON IN A BURROW?

A

lthough the actual times vary throughout the year, wombats generally spend about two-thirds of their lives in their burrows. What do they do there? Until glass-roofed or glass-sided burrows can be devised, and wombats persuaded not only to use them but also to behave naturally in them, what happens in the darkness of those narrow tunnels will probably remain something of a mystery. In studies of the behaviour of wombats in captivity in several zoos in Europe, Arnfrid Wünschmann made many observations of wombats dozing and sleeping. Using his descriptions, as well as my own observations of hand-reared wombats, some of which frequently returned to the house for periods of sleep, many years after being released into the wild, I think it reasonable to assume that similar behaviour occurs in the burrow and that a wombat’s day is spent in a manner something like what is described below. At the Perth Zoo, part of the wombat enclosure includes an underground tunnel system with a viewing area for the public. Observations on the southern hairy-nosed wombats there confirm most of these assumptions. 35

Wombats

Figure 4.1 Before entering the burrow, a wombat often uses a tree as a rubbing post.

A wombat’s day Early in the morning, usually before dawn and nearly always before sunrise, the wombat approaches the burrow where it intends to spend the day. Pausing a few metres from the entrance, the wombat rubs its flank against the rough bark of a tree (Figure 4.1), scratches itself once or twice, shakes itself vigorously if its fur is wet, and then moves closer to the burrow. Sometimes as it moves into the entrance tunnel it may leave a few drops of fluid in its path. This is a form of scent trail, and I will say more about it in another chapter. On entering the burrow the wombat has a choice of sleeping chambers, provided that it is the only occupant, as is often the case. A chamber deep in the burrow is usually chosen for the major part of the day’s sleep. On reaching the chamber the wombat scratches around the floor for a few seconds, pushing together, or sometimes scratching out, dead leaves and twigs that have accumulated there. If the ground is bare, it may scratch up some of the dusty soil on the floor before sitting on its rump, head down and eyes half shut. Its head drops lower and lower, and soon the stocky, thick-set wombat literally collapses, rolling over on to its side, often giving 36

What goes on in a burrow?

Figure 4.2 One of the sleeping positions adopted by the wombat (top). For much of the day the wombat sleeps on its back (bottom). Illustrations: © Peter Schouten

the ground beside it a few backward scratches with a forepaw before sighing deeply as it settles to sleep, either curled up in a ball or stretched out on its side (Figure 4.2). After an hour or so it changes its sleeping position; it may roll right over on to the other side – a movement it makes quickly and without raising its body off the ground at all, but rolling more in the fashion of a fat cylinder – or it may roll over on to its back. In this last position, which is probably the most relaxed attitude a sleeping animal can adopt, the front legs are loosely bent at the wrist and the back legs stretched out. The head is usually tilted right back, chin in the air, or sometimes turned to one side. Only an animal that is well protected on account of its subterranean way of life and has few natural enemies can sleep in such a very relaxed and vulnerable attitude. Several times during the day the wombat changes its sleeping position, rolling from its back to its side and on to its back again. It sleeps on its back 37

Wombats

Figure 4.3 Dozing near the entrance before emerging, the wombat lies prone. Photo: L Cunningham

Figure 4.4 In the prone position, the hind feet are sometimes tucked under the small tail.

more often and for longer periods on warmer days than in colder weather, probably because the sparser fur on its chest and abdomen allows some heat to be lost from the skin. While it sleeps the wombat also sometimes grinds its teeth, snores, yawns, sighs, scratches, snorts to clear its nose of 38

What goes on in a burrow?

dust, and produces long sonorous rumbles from various parts of its anatomy. It is probably just as well that it usually sleeps alone! Through the day the wombat often scratches itself to remove dust or dirt particles from the skin. It is also plagued by a number of external parasites, such as ticks and fleas, and by various kinds of blood-sucking insects (mosquitoes and certain flies) that frequently inhabit the burrow. The wombat usually spends the greater part of the day deep in the burrow, but in the late afternoon it moves slowly along the tunnel to within a metre or so of the entrance, where it crumples on to its stomach, the front paws tucked in under the chin and the body spread out so thinly that it looks as though it has been rolled out (Figure 4.3). The back legs are either stretched out behind or bent right under the wombat’s lower body, the back feet turned sideways and forming a kind of shelf under the small tail (Figure 4.4). The wombat dozes near the entrance until it is ready to leave the burrow.

Monitoring wombat activity During a study of bare-nosed wombats at Thredbo Diggings in the Kosciuszko National Park, Graham Brown and Greg Young used radiotelemetry to monitor the wombats’ activities. The researchers found that ‘while they are in their burrow they often remain completely still for many hours but short periods of activity will occur from time to time’. It is a likely guess that during those long periods of stillness the wombats are sound asleep, and that the short periods of activity occur when they scratch, change their sleeping position or move to another chamber in the burrow. As it sleeps the wombat’s breathing rate slows from a fairly rapid 30 times a minute to about 14 times. Graham Brown’s research has shown that the heart rate decreases rapidly when a wombat returns to its burrow, while its body temperature, which has increased by nearly 3°C during the time it was feeding and moving about, falls at a steady rate to about 34.7°C, its normal temperature, while it is resting in its burrow. This indicates that heat stored while the wombat is active on the surface is lost slowly while it is inactive, and it is thought that in this way the amount of energy used for regulating the wombat’s body temperature is reduced. All warm-blooded animals are able to keep their body temperature constant, and this normal body temperature is slightly above that of their usual surroundings. But in the wombat, this ability to regulate its body temperature decreases as the air temperature rises above 25°C, yet 39

Wombats

temperatures much higher than this are frequently found in many parts of the wombat’s range in summer, when temperatures of 35°C and even 40°C are not uncommon. A wombat exposed to temperatures of 35°C will become very distressed, and it probably could not tolerate such high temperatures for very long. Measurements taken by Graham Brown of the air temperature in burrows in summer showed that the temperature in the burrows never exceeded 25°C and was usually lower. During a period of extremely hot weather I inserted a maximum/minimum thermometer into a major burrow at a distance of three metres from the entrance and left it in place for three consecutive days. During this time the shade air temperature rose above 39°C for several hours each day and reached a maximum of 41°C on the third day, but the maximum temperature reached in the burrow was only 26.5°C. Thus the wombat is able to stay cool and comfortable in the burrow, and it does not emerge until the air temperature falls to an acceptable level, which appears to be when the surface air temperature is close to the burrow temperature. When in the late afternoon the wombat moves from the coolest, darkest part of the burrow to a chamber closer to the entrance, it is probably assessing the temperature to see when this is low enough for it to emerge. Even if it is cool enough, the wombat will not usually move out in bright daylight in summer, but will wait until dusk, although it may leave the burrow during the afternoon if the day is cool and overcast. At the other end of the scale, the wombat often encounters extremely cold conditions. In the mountain forests and subalpine areas where the majority of bare-nosed wombats live, temperatures often fall to 0°C and below. Southerns may also encounter freezing temperatures during winter, but the burrow again provides protection against these extremes, as its air temperature seldom falls below 4°C. In any case, the wombat is well able to cope with these low temperatures, and it will often leave the burrow during winter afternoons, although Graham Brown’s study showed that barenosed wombats spend less time above ground in winter – about five hours in winter compared with about eight hours in summer. He also found that wombats are less active while in their burrows in the winter than they are during the warmer months, indicating that wombats may expend less energy in winter. This would be an advantage, as it would offset the reduction in the amount of food available that may occur in winter when the grasses on which wombats feed grow more slowly, and it could be very important in an alpine and subalpine environment where there is often a deep snow cover. 40

5 LIFE ABOVE GROUND

J

ust as there is some variety in the ways in which a wombat spends its days underground, so there is considerable diversity in its nightly activities. Probably the main factors that cause this diversity are the seasonal conditions and the type of habitat; the prevailing weather conditions and the proximity of other wombats, and enemies, such as feral dogs or dingoes or humans, will also influence a wombat’s movements. But in spite of the many variations, the wombat’s life above ground does follow a general theme and this applies to all three species. The wombat emerges from the burrow, usually after sunset; it grazes for several hours, intensively at first, moving over part of its range as it feeds; it may interrupt its feeding to enter a burrow for rest or refuge; usually before sunrise it enters a burrow for the next day’s sleep. If the temperature and other external conditions are suitable, a wombat will usually emerge from the burrow about dusk. On some summer evenings, when temperatures stay above the wombat’s ‘comfortable’ temperature of 20°C, it will wait in the cool burrow until midnight or even later before emerging to feed. In winter, when food is often difficult to obtain, it may leave the burrow as early as three or four o’clock in the afternoon, particularly on overcast days or after a night or two of heavy 41

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rain or snow when little or no feeding has taken place. Wombats suffering from mange are also often seen above ground during the daytime, perhaps because in their weakened state they need more time to find food. After very cold nights southern hairy-nosed wombats often leave the warren in the late morning to bask in the sun. In some regions, where conditions are ideal for wombats, they are often active for many hours in the daytime. Very high densities of wombats often occur in some coastal areas of north-east Tasmania, where there is sandy soil suitable for digging deep burrows and improved pasture adjacent to dense scrub. Green and Rainbird estimated that one area of 800 hectares supported a population of 1000 wombats; I have seen 40 wombats grazing about midday, spread over an area of about 30 hectares. In the cooler months some of these wombats emerged from their burrows as early as 10 o’clock in the morning. Typically, the wombat pauses in the burrow entrance for a short time, and then moves out (Figure 5.1). Sometimes it then sets off to begin feeding, but often it sits down again almost immediately, either on the mound or very close to it, sometimes stretching out and lying prone for another doze, but more often sitting, head down and still apparently half-asleep. The eyes are closed, or nearly so, while the large nostrils dilate widely as the wombat samples the air.

Figure 5.1 After a brief pause at the entrance, the wombat moves out of the burrow.

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Figure 5.2 Sometimes the wombat halts for a scratch.

This investigation can take some time – I have seen a wombat sit for over an hour before it was apparently satisfied that all was in order for it to move off. This decision is made without warning: the seemingly drowsy wombat suddenly stands up and moves off purposefully in whatever direction its pre-examination of the air has decided it to go. Sometimes it travels without a pause until it is a considerable distance away from the burrow, and sometimes it halts not far from it for a scratch or to visit one of its rubbing posts (Figure 5.2). Here a further consideration of the scents and sounds seems to take place, while the back or the flanks, or both, are luxuriously rubbed back and forth against the trunk of a tree, an overhanging branch, a stump or a fallen log. This will leave a film of dust or of moist earth on the rubbing post if the burrow has been dusty or damp, and regularly visited posts often become smooth and polished. The sides of the head and the forehead also are sometimes scrubbed against the rubbing post, but it is the lower part of the back that usually receives the most attention (Figure 5.3). Occasionally during this rubbing session, the wombat will sit and scratch its flanks, or chest, or any other part of the body that needs attention. 43

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Figure 5.3 Any convenient log, branch or tree trunk may be used as a rubbing post. Usually it is the lower part of the back that receives the most attention.

Grooming Although a wombat often scratches itself, usually only individual parts of the body are groomed at one time. Most mammals groom their coats with meticulous care, and usually they have a long ritual sequence of grooming movements, which they perform regularly, beginning with the face and head and progressing through all the parts of the body: belly, flanks, back, hind legs, genitals and tail. A cat, for instance, always begins a grooming session by washing its face with its licked forearm before attending to the rest of its coat. At other times, if just one particular part of the skin is irritated by an insect or a grass seed or something similar, the cat immediately attends to the irritated area by scratching, licking or biting the fur. A wombat reacts to local irritations by rapid scratching movements or by rubbing hard-to-reach places against a solid object; but unlike other mammals, long grooming sessions in which the whole coat is successively cleaned do not occur. Nevertheless, all the wombats that I have handled have kept themselves extremely clean, which is remarkable considering the relatively narrow passages of their underground homes. 44

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Figure 5.4 When scratching the back, the hind leg is sometimes passed over the shoulder.

A wombat does not lick its fur to clean it, as most mammals do, except for licks and nibbles given periodically by the female to the pouch area; to do this, she has to sit on her rump, hind legs thrust forward in front of her, and bend her body over in an arc. At certain times in her ovulation cycle the female will pay considerable attention to the pouch opening, which becomes stained with a brown exudation from the pouch. Because of its position, it would be extremely difficult for her to clean inside the pouch by licking, and it is unlikely that this is ever done. However, a female will sometimes lie on her back, relaxing the strong circular muscle at the pouch entrance, and scratch carefully inside the pouch with the long curved claws of the hind foot, or with the small clawless inner toe. This clawless toe is usually also used when a wombat is cleaning inside the ear. Occasionally, too, the long clawed toes are inserted in the ear and moved carefully and slowly, but when scratching the rest of the body the movements are very rapid. The head, neck and chest are scratched with the hind leg, which is sometimes passed under a raised foreleg and sometimes passed over a shoulder while the wombat is sitting on its rump (Figures 5.4 and 5.5). 45

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Figure 5.5 The hind leg is also passed over the shoulder to scratch the neck. Illustration: © Peter Schouten

It may be either sitting or standing when a front paw is used to scratch the lower back, the rump and the belly. The hind paw is also used to groom the belly area in the same way as the female scratches her pouch: lying on its back, the wombat bends one hind leg up and sideways in order to scratch its belly (Figure 5.6). The male also scratches his scrotum while lying in this position. The hind paw is also used to scratch the belly area in another position, which is, I think, peculiar to the wombat. Standing on three legs, the wombat bends a hind leg sideways under the body to scratch the lower part of the belly and under the tail. This unique and slightly comical grooming movement is often made after the wombat defecates and before it sets out in search of food.

Scats Soon after leaving the vicinity of the burrow, the wombat usually deposits the first of the many heaps of scats it will produce during the night. 46

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Figure 5.6 The chest and belly are often groomed while the wombat lies on its back. Illustration: © Peter Schouten

In bare-nosed wombats, where and how they are deposited depend on the wombat’s age. An immature animal – one less than two years old – will generally seek cover in a patch of ferns or similar undergrowth where it will stand still with the small tail slightly raised and the eyes half-closed while it neatly drops the characteristic pile of cube-shaped scats. A mature animal usually chooses a rock, a stone, a stick, the raised edge of the road or some similar elevation as the site for its scats. It will back up to this elevation, and a male wombat will almost invariably make two or three long slow scratches on the ground in front of it, first with one front paw and then with the other, while it deposits its scats. A female bare-nosed wombat often chooses an elevated position for her scats, but usually only scores the ground with her forepaws when she is angry or aroused in some other way. Hairy-nosed wombats deposit most of their scats at latrine sites and these are used by many wombats. They are often found at popular scratching posts (Figure 5.7). They do not appear to favour raised surfaces as the bare-nosed wombats do. All wombats will also always investigate any patch of freshly disturbed ground that they come across, whether it has been disturbed by scratching 47

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Figure 5.7 Northern hairy-nosed wombats deposit their scats along their pathways and at rubbing posts. Photo: A Horsup

lyre-birds, digging echidnas or gardening humans, and they almost invariably deposit a pile of scats on the freshly dug ground.

Dust-bathing Often too, a wombat will seek out a patch of sand or dusty soil where it will proceed to have a dust-bath. Lying on its side it scratches and scoops the 48

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loose sand or soil over its flanks (Plate 12). Sometimes it rolls over and dustbathes on the other side as well, and quite a large depression can be formed in the soft ground. ‘Wombat-wallows’ are often found at the bases of large trees, as well as on sandy tracks, creek banks and, in some areas, beaches.

Food and feeding If there are suitable tussocks of some of the grasses favoured by the wombat in the vicinity of the burrow, it may graze there for some time, but more often it moves right away from the area, grazing occasionally as it goes, until a chosen feeding place is reached. The location of this will vary, of course, with the seasons and the climatic conditions, and which grasses a wombat will choose depends on what is available at that time (Figure 5.8). John McIlroy’s study in the Brindabella Mountains near Canberra showed that bare-nosed wombats prefer the coarse, high-fibre grasses. He found that several species of Poa, or tussock grass, were the plants most commonly eaten in the forest areas, while in the open, more pastoral country kangaroo grass (Themeda australis) and wallaby grass (Danthonia penicillata) were the favourites. Oats (Avena sativa) growing in a newly planted pine plantation were favoured by a few wombats. Tall sedge (Carex appressa) and spiny-headed mat-rush (Lomandra longifolia) were also eaten at times.

Figure 5.8 This young bare-nosed wombat is eating the young shoots of weeping grass on a recently dry swamp bed.

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When following bare-nosed wombats closely while they are feeding in the local coastal forest in East Gippsland, I have noticed that they eat a wide variety of plants, all monocotyledonous (i.e. ‘having one seed leaf’. Monocotyledons have long parallel-veined leaves). The most favoured grasses are spear grass (Stipa sp.) and fine tussock grass (Poa sp.). Kangaroo grass, elsewhere a major food item, is not common in this forest, but small patches of it do occur, and these are popular with wombats. Other grasses that are eaten from time to time include weeping grass (Microlaena stipoides) and reed bent grass (Deyeuxia quadriseta); the new tips of forest wire grass (Tetrarrhena juncea) are relished in the spring. Several species of sedges (Carex sp.), rushes (Juncus sp.), club-rushes (Scirpus sp.), mat-rushes (Lomandra sp.) and several other plants that I have been unable to identify are all part of the coastal wombat’s diet, as are some of the introduced grasses in the area, such as paspalum (Paspalum dilatatum) and parramatta grass (Sporobolis africanus). At the western extreme of the bare-nosed wombat’s range, in the dune country of the Coorong and Messent National Parks in south-eastern South Australia, Katy Mallett and Brian Cooke investigated the diet of the wombat by analysing wombat scats. They found that the bulk of any individual wombat’s diet appeared to be made up of two or three plant species, although the species varied between wombats and seasons. In any season most of the diet consisted of only a few plant species: Australian salt grass (Distichlis distichophylla), perennial rye-grass (Lolium perenne), spear grass (Stipa sp.), tassel rope-rush (Hypolaena fastigiata), wire rapier-sedge (Lepidosperma semiteres), hair-sedge (Tetraria capillaris), some herbaceous material and several unidentified grasses. The hairy-nosed wombats also prefer the high-fibre grasses and sedges. Southerns feed mostly on spear grasses (Stipa nitida and Stipa eremophila), but in extreme droughts they have been seen browsing on bluebush (Maireana sedifolia) and bindyi (Sclerolaena spp.) The bulk of the northerns’ diet consists of four species. Andrew Woolnough studied their diet and found that it was composed of threeawned grasses (Aristida spp. 35%), bottle-washer grasses (Enneapogon sp. 28%), the introduced Buffel grass (Cenchrus ciliaris 27%) and 4% was the sedge (Fimbristylis dichotoma). When a wombat reaches a feeding area it often remains there for some time, eating hungrily. A feeding wombat’s jaws work constantly as its head moves over a tussock or tuft of grass while the leaves are arranged in the mouth. Then it gives a slight jerk of the head – up, down or sideways – so 50

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Figure 5.9 Leaves of coarse grasses such as kangaroo grass or spear grass may be jerked free of their leaf bases.

that the leaves are either broken off or else pulled cleanly from their axils or leaf bases (Figure 5.9). On the sides and floors of the gullies a wombat often pauses to sample some of the larger rushes and sedges, including thatch saw-sedge (Gahnia radula), more aptly known as sword grass. The razor-sharp leaves of this plant have long white bases which are apparently a wombat delicacy, but the green part of the leaf also is sometimes eaten. A wombat pulls the sword grass leaves free from the base of the plant by biting a leaf near its base, carefully arranging it in the mouth and then giving it a sharp, sideways, upward tug. If the leaf does not pull free the first time, the wombat jerks its head again and again until it does. Usually only the white part of the stem is eaten, the rest being grasped in a front paw and discarded. Wombats are remarkably dexterous with their front paws and often use them to rearrange stems or to remove from their mouths any stems they do not wish to eat. In this grasping action, all the digits are bent over so that the claws are touching the pads on the palm of the paw. The young seed-heads of many species of grasses are also sometimes consumed by wombats, the dexterous front paws frequently being used to remove unwanted stalks from the mouth. 51

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Figure 5.10 Occasionally a wombat will tear strips of bark from tree trunks.

From time to time when it is eating grass, a wombat will deliberately select and eat dry leaves and stalks, and occasionally it will tear a strip of bark from the trunk of a tree and chew small quantities of it, but much more is usually torn off than is actually eaten (Figure 5.10). The bark probably serves mostly to keep the teeth in trim, and it is usually trees with a fibrous type of bark that are chosen for this purpose. Low-growing and fallen twigs and branches are also frequently gnawed in order to keep the ever-growing teeth sharp and at their proper length. Burnt logs and sticks are often nibbled, and some of the charcoal is crunched up and eaten. When it is digging a burrow, a wombat often uncovers roots, both large and small, and it bites them off sharply or chews the larger ones, in order to remove them from the tunnel, but it does not appear to eat any of this root material. Other observers have recorded the roots of various trees such as stringybarks, and of plants such as mat-rushes and Poa grasses, being dug up and eaten. Sometimes, particularly during drought or other times of scarcity, it will scratch away the surface soil to uncover small roots of grass and other plants, which are nibbled off (Figure 5.11). In some parts of their range, southern hairy-nosed wombats dig over large areas to uncover the corms of nut grass (Cyperus rotundus), which forms an important part of their diet, especially during droughts. 52

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Figure 5.11 In times of drought, bare-nosed wombats will scratch away the surface soil to uncover small roots, which are nibbled off.

Mat-rush leaves are an important food item in all parts of the barenosed wombat’s range, including those parts which are covered in snow in winter. Digging being no problem to a wombat, it simply scoops out a hole in the snow until it reaches a suitable plant. Ian Pulsford observed a wombat digging on a snow slope in the Kosciuszko National Park. It had dug through 30 centimetres of snow to reach mat-rush leaves, which it pulled out and ate hungrily (see Plate 13). Several other holes scattered over the same slope indicated that this was a regular feeding method. In a very different habitat, the sand dunes on the southern Victorian coastline, Martin Schulz observed bare-nosed wombats eating marram grass (Ammophila arenaria) and hairy spinifex (Spinifex hirsutus) (see Plate 7). Moss appears to be a wombat delicacy, the soft green varieties that grow on fallen logs and branches being gnawed off with apparent relish (Figure 5.12). Some species of moss that grow among damp grass are favoured when they are green and moist, but generally ignored when they are drier. It is possible that mosses are eaten for their water content as they have little nutritional value. When rain and warm weather followed a bushfire in the coastal forest in 1983, many kinds of fungi appeared in the burnt forest, and wombats were occasionally seen eating some of these, including edible mushrooms, when they were the only food available in the forest. Pausing beside a 53

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Figure 5.12 Moss growing on a fallen log appears to be a wombat delicacy.

growing mushroom, a wombat would take one large bite out of it and walk on, chewing as it went. These and other fungi are often found with similar bites taken from them, but wombats are not always responsible – I have also observed swamp wallabies eating fungi.

Other night-time activities In the early part of the night a wombat grazes almost continuously, moving from tussock to tussock, sitting on its rump from time to time. Occasionally it pauses, head up, to listen and sniff the air, before lowering its head to graze again. After an hour or two, when its initial hunger is satisfied, it eats more sporadically, sits down more often and roams further between bouts of grazing. There is a great variety of ways in which a wombat passes the night, as so many factors can influence its activities. Usually it will stay above the ground, eating and travelling, for the entire night, but sometimes it will remain above ground for only three or four hours before retiring to a burrow, either for a rest or to do some housekeeping – cleaning out the tunnels or enlarging them. Then it emerges again to continue feeding, but it may disappear into another, or the same, burrow again later in the night. If it is disturbed in any way while it is above the ground, it will rapidly make for the nearest burrow, or a hollow log if there is no burrow handy, 54

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and dive into it. In this way a wombat may use three or four burrows in one night, and the burrow it finally enters for the next day’s sleep may not be the one it left the previous evening.

Travelling During its travels through the night, the wombat uses mostly well-worn paths. If the undergrowth is heavy, these will take the form of tunnels through the vegetation, wombat-high and wide, or a little larger if they are also used by wallabies, as often happens. In more open country there are also well-trodden paths used by a variety of animals, and although the wombat may wander off the path while grazing, it usually regains the path before moving on to a new area. If there are man-made tracks or roads along the way, these will also be used for as long as their direction suits the one chosen by the wombat. Although it has the reputation of being slow, this is actually true only when the wombat is moving short distances, grazing from tussock to tussock, for instance. More often it covers the ground remarkably quickly, as anyone who has tried to follow a wombat through the bush has found. In the slow, deliberate walk and in the faster amble, the hind feet are turned inward and are hardly raised, so that the soles slide over the ground. The front feet are lifted slightly and placed more deliberately, and the hindquarters sway from side to side at the hips in a graceful, if slightly comical, motion. Another gait, a kind of rocking gallop, is rarely used by an adult unless it is fleeing from danger. Both back feet strike the ground at the same time, followed by both front feet also almost simultaneously, and the wombat can cover a considerable distance at a surprising speed. It can also move quite quickly at a purposeful, heavy-footed trot, and often uses this gait when about to engage in hostilities. It moves up and down slopes with little change in speed, but sometimes, if the slope is particularly steep, the wombat spreads its front legs in front of its body, tucks its hind legs forward and, sitting on its flat rump, slides down the slope. This manoeuvre is often performed on steep river banks, and wombat ‘slides’ can often be found on these, and also on snow slopes. When walking in soft snow, a wombat places its feet carefully and deliberately, packing the snow down with each step. When the snow cover is deep, the banks of streams are often the only places where the grasses are not buried under the snow, and the slopes leading to these banks are usually well furrowed by wombat chutes. 55

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Wombats are also efficient swimmers over short distances. With the heavy body two-thirds submerged and the head tilted back to keep the nostrils clear of the water, the short legs ‘dog paddle’ under the water. There is no splashing and all an observer sees is an apparently floating wombat moving slowly and silently through the water.

Drinking Grassy creek and river banks are popular feeding areas at all times, but a wombat rarely drinks from the stream or any other free water except when all the grass has yellowed and lost most of its moisture. When a wombat does drink, it makes very little sound. The muzzle is thrust into the water, but at an angle so that the nostrils are still above water level. The lower jaw then moves up and down rhythmically as the wombat apparently sucks the water into its mouth. It swallows regularly and can drink nearly a litre, without a pause, in three to four minutes. I have watched a wombat drink without pause for as long as eight minutes (Figure 5.13).

Home range As part of his study of the ecology of bare-nosed wombats, McIlroy attached small radio-transmitters to several wombats, each transmitter

Figure 5.13 This wombat drank for eight minutes without pausing.

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having a separate frequency. The transmitter was attached to the wombat by a simple chest harness and an aerial loop around the neck, and McIlroy was able to receive signals from the transmitters on a modified walkietalkie set used in conjunction with a hand-held directional loop antenna. The maximum range for reception was about 300 metres when the wombat was above ground and 150 metres when it was down a burrow. By rotating the antenna until he received a signal and then finding the direction from which the strongest signal came, McIlroy was able to pinpoint the wombat’s position. With experience, he was also able to determine whether or not the wombat was moving, to estimate its speed if it was, to determine whether or not it was feeding and how intensively, and to locate a wombat’s position in its burrow. A wombat can cover a considerable distance during a night’s grazing and travelling. McIlroy radio-tracked one wombat for eight hours one night, during which it covered a distance of about three kilometres, and I have followed a wombat for nearly four kilometres before it disappeared into a burrow. In areas where there are several burrows close together, as often happens along creek banks, and there is a good supply of suitable grasses nearby, a wombat will still wander for one to two kilometres in the course of a night’s grazing. The area over which an animal normally travels in pursuit of its routine activities is, by definition, its home range. In the case of the wombat – and the situation is similar in many other mammals – the home range includes the wombat’s burrows, feeding places, rubbing posts, dust-bathing patches and so on. These places are connected by a network of paths regularly used by the wombat. By radio-tracking, McIlroy was able to estimate the home range sizes of six adult wombats, and he found that the size and shape of a home range mostly depended on the pattern of distribution of used burrows and suitable feeding areas. For example, where suitable burrow sites were in forest that was close to pasture or other good feeding areas, the home range was as small as about five hectares; but when a wombat regularly fed in an area at some distance from its burrows, the range was as large as 23 hectares. The size of a home range may increase or decrease under different seasonal conditions. During winter and in periods of drought wombats may extend their home ranges to take in more distant feeding areas. In the summer of 1982–83, when severe drought conditions prevailed in the coastal forest, all the wombats I was studying increased their ranges 57

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considerably. One was regularly found grazing in a clearing nearly one kilometre from its usual home range. A bare-nosed wombat’s home range appears to have a core area – a part of the home range that is used more intensively than the rest. The term ‘home range’ is often used synonymously with ‘territory’, but the two are not necessarily the same. More often the territory is a smaller area, situated within the home range, which the animal will defend against the intrusion of others of its kind. The bare-nosed wombat does not appear to consistently defend any particular part of its home range, not even the core area. Sometimes it will chase another wombat out of a burrow, but on another occasion it will share it with one, or even two, others. At times, too, a wombat will aggressively defend a certain favoured feeding area. This seems to happen more often during periods of food scarcity, such as winter or drought. When grass is growing abundantly, the same wombat in the same feeding area will tolerate another grazing only a few metres away. Southern hairy-nosed wombats also have a core area – the grazing halo around the warren, which may extend for up to 0.7 kilometres from the warren. Unlike bare-nosed wombats, they will defend this core area as a territory, chasing away any wombats from other warrens. The warrens are surrounded by defecation wallows and rubbing posts which are all marked regularly with faeces. Graeme Finlayson and several colleagues also used radio-tracking to monitor the activities of 16 adult southerns. They found that these wombats used up to five warrens but they generally centred their activity around one or two large, multi-entranced warrens. Their home range size varied from 1.3 to 4.8 hectares and the home ranges of both males and females usually overlapped considerably. Northern hairy-nosed wombats have a home range of about six hectares but in the wet seasons this is halved and the wombats are only active for about two hours per night. Johnson and Crossman studied 28 northerns for a year and found that the feeding ranges of wombats of the same sex did not overlap but the ranges of females overlapped those of one or more males.

Social behaviour – bare-nosed wombats It is quite common among mammals for the home range of one individual to overlap with that of another, or several others, of the same species, but usually the overlap is confined to the common use of the network of pathways. Bare-nosed wombats not only have overlapping pathways, but also share the use of their burrows, rubbing posts and feeding places. In 58

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spite of this, wombats are usually found alone; they are classed as solitary mammals. They form no social group such as a herd or pack. Even where burrows are thickly clustered and numbers of wombats live in relatively close proximity to one another, they form a loose collection of individuals rather than a colony. However, although a wombat is not gregarious, it does have social contacts with other wombats; it can communicate with and recognise the other individuals that share its home range, and it is quick to detect the presence of a stranger. Unfortunately, it is difficult to observe and study these social interactions because they happen so infrequently. Nevertheless, at some time during a wombat’s nightly activities, there is a fair chance that it will meet another wombat engaged in similar activities. The chances of such a meeting are not so likely in the less densely populated habitats, but it is not rare to see two or three individuals feeding within 30 or 40 metres of each other on a favourable pasture (Figure 5.14). If there is a disturbance such as a ‘dog alert’ or the onset of severe weather – a thunderstorm or hailstorm, for instance – while wombats are sharing a feeding area, they are all likely to seek refuge in the nearest burrow, two or three animals disappearing into the same entrance and remaining there for an hour or more, sometimes for the rest of the night and the following day. When two wombats approach each other while feeding or moving from place to place, they usually pause before they are less than three metres

Figure 5.14 Bare-nosed wombats keep at least 30–40 metres apart when they are feeding on a favoured pasture.

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apart. If they are feeding they generally resume grazing, keeping at least that distance from one another. Three metres, or thereabouts, seems to be the wombat’s individual distance; it will either attack or move away from any wombat which approaches closer than that. This produces a kind of personal territory that the animal carries around with it. If a close approach is made by another wombat, a low guttural growl of warning is often given, as well as a rasping hiss, which seems to signify alarm as well as anger. This high, loud call, which may rise to the level of a screech, is made repeatedly as each breath is expelled. The screech builds up from a gentler call often made by young animals, a soft ‘huh huh’ repeated several times, which seems to signal uneasiness. The ‘huh huh’ call is often made by a young at heel when it has lost sight of its mother; it appears to be a contact call, as she will usually ‘huh huh’ in reply. It seems likely that bare-nosed wombats sharing a home range have a dominance hierarchy or pecking order, but it is not clear how or on what basis the rank order in the hierarchy is determined. In most animals, dominance is usually established by fighting or by displays of threatening behaviour, but it also often relates to size and sex, and this may also be true of wombats.

Social behaviour – hairy-nosed wombats Living in warrens, in closer contact with each other than the bare-nosed wombats, male southerns appear to have a well-defined dominance hierarchy. Matt Gaughwin reported a dominant male defending an oestrus female from attentions of other subordinate males, while females appeared to be subordinate to all adult males. Dominance relationships were not apparent between females. Little is known of the social structure of the northern hairy-nosed wombat but it appears to be more solitary than the southern and probably has a social structure similar to that of the bare-nosed wombat. The vocalisations of the hairy-nosed wombats are confined to short harsh coughs, which are uttered when the wombats are fighting.

Aggressive encounters Sometimes, when two bare-nosed wombats meet, more aggressive sounds are made. Like most animal sounds, these are difficult to describe, but one appears to be made by the tongue hitting the palate while the breath is 60

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drawn in and a flat ‘chikker chikker’ is the result; the other is a slightly more guttural sound, not unlike the hoarse, churring sound made by an angry brushtail possum. These vocal signals may also be made by a wombat when it hears, or smells, another a considerable distance away, and they are often answered by similar chikkerings and churrings from the second wombat. A series of calls and answers can continue for some time until the second wombat has either passed the first, still at some distance, and gone on its way, or until it has approached the first more closely, when a chase often results. In several chases I have watched, the wombat that is first on the scene almost always chases the second arrival, but the roles may be reversed if the chased wombat stops and turns, calling again. Both wombats may sit down while another duet of chikkers ensues before the chase resumes – and now either wombat may be the pursuer. In one chase sequence I saw the roles of pursuer and pursued change four times before both wombats settled down to graze about 30 metres apart, still chikkering occasionally. Robert Taylor, studying wombats in north-east Tasmania, observed three lengthy chases, the chased wombat often making veering movements to avoid being reached by the pursuing wombat; throaty snorts and nasal squeals were heard during the chase. Two of these chases involved a male pursuing another individual near the boundary of its home range. Both the aggressive chikker and the rasping churr can be the prelude to a fight. They are often interspersed with other hostile gestures. Standing, or sitting with the front feet wide apart and the body humped to make it appear larger, the wombat’s head swings from side to side in a feigned biting action, while the teeth grind together and the whole body shivers. Not surprisingly, this display of threat usually causes an approaching wombat to retreat to a safe distance, but occasionally it will stand its ground and make similar aggressive signals. What happens next probably depends on several factors such as the age, sex and, possibly, rank order of the confronting wombats – or it may just depend on their mood at the time. Too few encounters have been seen or reported for any general conclusions to be drawn. Few of the aggressive encounters that I have watched have resulted in an actual physical contact; the majority ended, after a mutual exchange of unpleasantries, in one of the contestants turning away and leaving the field to the other. Nevertheless, if the scars and wounds carried by almost all adult wombats are any indication, physical clashes do occur quite often. Scars on the forehead and ears and the upper part of the muzzle are very 61

Wombats

Figure 5.15 The ears often show signs of past battles.

common; they are probably the results of head-on conflicts, which frequently occur in burrows or at burrow entrances when the wombat in residence resists the entry of another wombat. The ears, flanks and back often show signs of past battles (Figure 5.15). I saw some of these wounds delivered during a fight between two adults, a large grey male and an even larger black female. These gradually grazed closer and closer together until they were about five metres apart, when they both sat down and chikkered at each other for a few moments. Then the male suddenly stood and charged the female, lunging at her flank, tearing a strip of fur from it. She quickly turned and, thrusting her head upward, caught his right ear in her teeth. Holding on grimly to the ear, she shook her head violently several times, while the male tried to shoulder her away. Blood was oozing from his ear when he did finally wrench himself free. Almost immediately, the female jabbed at his head again, but this time the male whipped his whole body round in a 180 degree turn so that his rump was presented to her charge. She bit his rump savagely several times, but the male had had enough. Giving a few rapid backward 62

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kicks with his hind legs, he lowered his head and broke into a lumbering gallop, which he maintained until he disappeared into thick undergrowth 50 metres away. The female pursued him for only a few metres before turning and ambling away in the opposite direction. A few nights later these two wombats met again. Standing about five metres apart, shivering and chikkering at one another, they both began to score the ground in front of them with their forepaws. The grey male bit savagely and repeatedly at the trunk of a small sapling before he turned and trotted quickly away, apparently disinclined to repeat the previous experience.

Olfactory signals As well as postures and vocalisations, a wombat has other ways of communicating with others of its kind: by olfactory signals. The simplest of these, the scent emanating from the animal’s body, probably allows individuals to recognise each other, particularly those sharing a home range. It is likely that they also recognise each other’s scats and can distinguish them from those of a stranger to the area. Like most planteating animals, wombats produce large quantities of faecal material – on average, 80–100 individual scats in a night. As it wanders about its home range, a wombat leaves these scats, and hence its own particular smell, scattered all over the area. These scats then act as landmarks or as familiar, reassuring guides. It is noticeable that often ‘new’ objects will be marked with scats – a newly fallen branch, a dislodged stone, freshly disturbed ground, any article left about by campers, and so on. Where we use the sight of familiar objects to guide us, the wombat, with its apparently poor eyesight and nocturnal habits, relies on its highly developed sense of smell. By deliberately placing its scats on elevations such as sticks and stones, logs and tussocks, and any other prominent place it can find, it is almost certainly refreshing its own signposts, as well as ensuring that the smell is more noticeable: this not only will disseminate more widely but is also closer to nose height (Figure 5.16). The wombat’s scats probably also convey messages to any other wombat that comes by. Although we have no way of knowing the actual nature of these messages, they probably include information such as the animal’s sex and age. It is well known that many animals produce scented substances, called pheromones, in specialised glands; sometimes the secretions from these glands are deliberately placed on the ground or on 63

Wombats

Figure 5.16 Any additions to the bare-nosed wombat’s landscape will be marked with scats, particularly objects that are slightly elevated, such as a fresh mushroom (left) or a fallen branch (right).

some other surface, and this behaviour is called scent marking. It is generally used as a method of communication between animals. Since urine and faeces are so readily available, it is not surprising that they are frequently used as scent marking substances. Secretions are released from glands in the body into the urine and faeces before these are voided. The wombat has these glands located in the cloaca – the single posterior opening of the marsupial’s body.

Reproductive signals In many mammals the function of the pheromones passed with the urine is to signal the reproductive status of females. Observations by a number of research workers have shown that males of many mammal species sometimes make a distinctive grimace, a kind of lip-curling, when they encounter the urine of females of their own species. This grimace is known as ‘flehmen’, and typically it is made by the animal standing with its head stretching up and its mouth open while it retracts the upper lip, thus baring the gum and wrinkling the nose. Sometimes the animals make rapid licking and mouthing movements during or after showing flehmen. Although its precise function is not known, flehmen often occurs before or during early courtship, and it is believed to be involved in the olfactory testing of the female’s urine by the male to determine her state of sexual readiness. Flehmen has been observed in a wide spectrum of mammals, 64

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ranging from bats to dugongs and including most of the hoofed mammals, and it has been recorded in the southern hairy-nosed wombat. During the preliminary phase of courtship between captive animals, Matthew Gaughwin observed flehmen on a number of occasions when the male sniffed intensely at areas of ground where the female had previously urinated and once when the male had sniffed the female’s cloacal region. While he was sniffing, the male hairy-nosed wombat moved his nostrils backward and forward erratically, occasionally snorting and pawing the ground with the front foot. After sniffing intensely for several minutes the male raised his head and showed flehmen by retracting his split upper lip, causing the lip to move sideways and upward and exposing the large incisors. Bouts of sniffing, interspersed with flehmen, continued for up to 20 minutes. Gaughwin also made an observation in the field of a male hairy-nosed wombat showing flehmen when it stopped near a burrow to sniff a pile of scats. Flehmen also occurs in bare-nosed wombats. Graham Brown observed it in wombats in the Kosciuszko National Park, and I have seen it exhibited on two occasions by an adult male wombat that regularly visited my home. On the first of these, a female who was then nearly two years old had entered the house a few hours before the male and had deposited a pile of scats outside the wombats’ entry door. The male paused at the pile of scats for several minutes, moving his head backward and forward over them with his nostrils dilated widely; then he lifted his head slightly and grimaced in the way that Gaughwin had described. He also mouthed and salivated while sniffing the scats. He showed flehmen several times before leaving the scats, but he then appeared to have no further interest in them, not even pausing as he passed them on leaving the house an hour or two later. The second time I saw this male exhibit flehmen was in a similar situation in the field to the one described by Gaughwin. The wombat, which had just left a major burrow late in the afternoon, stopped to sniff one of several piles of scats that were scattered near the mound. He sniffed the scats, raised his head and grimaced, and then pawed the ground with one front foot. He then turned and deposited some scats of his own very close to the pile he had sniffed, scratching the ground vigorously as he did so. Adult wombats rarely urinate, but they do occasionally produce very small quantities of urine at the same time as they produce scats. It is not possible to say whether this wombat was showing flehmen in response to some urine on the scats, or to the scats themselves or to other secretions on the scats. 65

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Scent trails As well as being released with the scats, a secretion from the cloacal glands is often produced when a wombat rubs its rump against a tree or an overhanging branch. It is produced as a brownish liquid, and it carries a very strong ‘wombat’ smell. This smell is also very noticeable when, after depositing its scats, a wombat sometimes deliberately rubs its cloacal region back and forth over the scats. A trail of brown drops is also often secreted as a wombat enters or leaves a burrow and as it moves about its home range. I have not seen wombats show flehmen in response to this secretion, but it does appear that they can follow a scent trail unerringly, even when it is several days old. I have collected the brown liquid from a polished wooden floor, where it was often deposited by wombats visiting the house, and used it to create a ‘wombat trail’ by placing drops of it at half-metre intervals for 25 metres across a clearing in the forest where there were no district game tracks, incorporating two sharp bends into my trail. When a 15-month-old hand-reared female, walking at my heels, was led past one end of this trail, she immediately turned away from me and followed the trail and its bends, sniffing the ground as she went and stopping less than a metre past the end of my test trail. She then returned to me, still sniffing the ground along the trail. On another occasion about three months later, this female located a burrow she had not previously visited, apparently by following a scent trail for about 100 metres. She sniffed the ground frequently and became quite agitated when she seemed to temporarily lose the scent. When she reached the burrow and entered it, I heard chikkering sounds coming from inside, and the female emerged after only a couple of minutes. An adult male was later seen leaving this burrow, and I assumed it was his scent trail that she had followed. Ken Green studied bare-nosed wombats’ movements in the Snowy Mountains by following their tracks in the snow. He noticed that the wombats found their way by scent marking, with one step in four having a drop of scent visible in fresh snow.

And so to bed … The last of the wombat’s scats are deposited shortly before it approaches the burrow where it will spend the following day. This may be as early as midnight in winter, especially if the wombat has been out and about since

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Figure 5.17 With a final sway of its broad rump, the wombat enters the burrow.

mid-afternoon, or after sunrise in milder weather, but generally a wombat has made its way to the chosen burrow before the sun is up. Pausing only briefly in the entrance to sample the air in the burrow, and sometimes giving itself a vigorous shake to rid the coat of any rain or dew it may have gathered, with a final sway of its broad rump it disappears into the dark tunnel (Figure 5.17).

67

6 FROM BIRTH TO MATURITY

A

s in all marsupials, a newborn wombat is extremely undeveloped and very small – about the size of a small bean. Birth occurs after a very short gestation period, probably only about 22 days; following its birth the young makes its way to the pouch, where, suckling from its mother, it grows and develops for about eight months. It leaves the pouch permanently at about 10 months of age, but it may still stay with its mother for a further 8–10 months before it is finally independent.

Birth The birth of a wombat has not, to my knowledge, even been observed, but it undoubtedly is very similar to that of other marsupials. The mother’s pouch itself is clean and moist. A dry brown scale, which from time to time exudes from the pouch along with dust and other foreign matter, forming a dark encrustation around the pouch opening, has been wiped away by the mother’s tongue. At the time of birth the mother probably adopts the same position as the one she uses when cleaning the pouch opening, that is, sitting on her rump with the hind legs extended forward, so that the cloaca, which is also the opening of the birth canal, is directed slightly upward. 69

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If it follows the pattern of other marsupials, the tiny, pink, newborn animal emerges head first from the birth canal. It is only about 15 millimetres long and weighs about half a gram. Its skin is moist and completely hairless (Plate 14). Although its mouth, front limbs and shoulders are well developed, its eyes, like most of its other organs, are still embryonic. On the front feet, the toes are fanned out and are armed with sharp, curved claws. The neck and chest muscles are also well developed; in marsupials in which birth has been observed the newborn uses these and the front limbs in a series of reflex movements as it moves rapidly from the birth canal towards the pouch. It grasps the mother’s fur in its front claws, using the front legs alternately, and its head swings from side to side as it goes. Apart from her previous washing of the pouch opening, the mother makes no attempt to help the newborn to reach the pouch. The embryo-like wombat probably enters the pouch only a minute or two after birth; in the red kangaroo the journey takes less than five minutes, but the distance is much shorter for the wombat. Shortly afterward it attaches itself to the teat. The newborn’s lip are joined at the outer edges so that its mouth is a small open circle; when the small swelling at the tip of the nipple is sucked in, it expands inside the mouth so that the young becomes firmly attached to it – so firmly that any attempt to pull it off will tear the skin around the mouth and make it bleed. It was this bleeding that gave rise to the once widely held belief that marsupials were actually born in the pouch by budding off from the teat. The pouch itself provides a constantly warm, humid environment for the growing wombat, which, until it is about seven to eight months old, cannot control its own body temperature but relies completely on the mother’s body warmth.

Life in the pouch During its early life the tiny wombat grows rapidly. After only one month it is about seven centimetres long and weighs about five grams (Figure 6.1). There are small differences between the three species of wombats, according to their differences in size. (See Growth and Development Table, Appendix 1. The range of weights shown in this table reflects the considerable variation in the growth weight, which is influenced by the condition of the mother and her size, as well as the species of wombat.) At one month the shapes of its ears are recognisable, but they are still fused with the skin of the head; the hind legs are beginning to develop; the outer 70

From birth to maturity

Figure 6.1 At one month the hairless young is about seven centimetres in length, measured from the crown of the head to the rump. Photo: P Presidente

edges of the lips are still joined together, and it is still constantly attached to the teat, sucking small amounts of milk at frequent intervals. In the next two months the small pouch young doubles its length, while its weight increases to about 150 grams (see Plate 15). Facial structures – eyelids, nostrils and so on – are developing and the ears are fully unfolded. Whiskers are beginning to appear beside its mouth and on the cheeks and eyebrows, but it still has no other sign of hair for another two to three weeks, when very fine fur appears on its ears. The skin is still pink and wrinkled in some places (see Figure 6.2 and Plate 16). By the time the young wombat is four months old it weighs nearly 400 grams, and its eyes are open. A month later it has a fine layer of fur on its limbs and its lower incisors have erupted. Although it still suckles frequently it is no longer permanently attached to the teat, and its lips are now fully separated from one another. Much of the time it lies on its back, swinging comfortably in the pouch. As the young grows and needs more room, the pouch expands. Green and Rainbird found that there is much individual variation in the way the pouch enlarges, but that generally, by 71

Wombats

Figure 6.2 At three months of age the crown-to-rump length is about 15 centimetres. The young is still firmly attached to the teat. Photo: P Presidente

the time the fine fur is developing, it has expanded for up to 12 centimetres in any or all directions from the mid-point of the opening. Usually, the pouch expands more anteriorly – towards the mother’s chest – than in the other directions. Very fine fur, only one to two millimetres long, covers much of the young wombat’s body by six months of age, and now it is ready to take its first look at the world – or what it can see of it from the opening of the pouch. A pink nose or forepaw, or occasionally a whole back leg, can sometimes be seen poking out of the pouch (Figure 6.3); but to look out the young wombat either lies on its front with its front paws tucked in and its head framed in the opening (see Plate 17), or it sits hunched over, so that its head and all four feet are near the pouch opening (Figure 6.4). The young wombat’s upper and lower first molars are usually present by the time it is six months old, and the lower incisors are about three or four millimetres long. The upper incisors also erupt about this time. Occasionally, while the mother is feeding, the young in the pouch will bite at a blade of grass or extend a small forepaw, grasp a blade and pull it towards its mouth. It probably does not eat it at this stage, but it makes its first investigation of grass in this way. 72

From birth to maturity

Figure 6.3 Occasionally the young wombat’s back leg may be seen poking out of the pouch. Note the pale sole of the foot which later darkens. Photo: R Green

Figure 6.4 The young wombat often sits in the pouch with its head and feet visible. Illustration: © Peter Schouten

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No actual observations of the mother cleaning the young in the pouch, or attending to it in any way, have been recorded. It is not known how the young wombat copes with its waste products, but it seems likely that the mother licks the cloaca of the young when it is very small, to remove urine and faeces in the same way as a kangaroo mother does, although it is anatomically much more difficult for a wombat to reach its head into the pouch. By the time the young is detached from the teat it is about 15 centimetres long, and it would be almost impossible for her to reach over and into the pouch entrance. Young, fine-furred pouch young have been seen to push the tail section out of the pouch and pass urine and small faecal pellets.

First ventures out of the pouch The fur grows longer and thickens, more teeth – the pre-molars and second molars – break through the gums, and by seven months the young, which now weighs about two kilograms, probably ventures out of the pouch when the mother is in the burrow. Young wombats as small as this are rarely seen outside the burrow. However, from my observations of semi-tame wombats it appears that, when the young first begins to explore its immediate surroundings, probably in the burrow, it keeps close contact with the mother, its small body always touching hers at some point. From time to time it pushes its head into the pouch to suckle vigorously. The teat has gradually become greatly elongated – as much as 10 centimetres long and thinner than a pencil – and it sometimes even protrudes from the pouch opening. At this stage, too, the young begins to play with its mother, biting and chewing her fur or pouncing on her paws, and she patiently allows it to climb all over her body and drape itself across her neck, even her face, while she sleeps (Plate 18). As soon as she makes a move to rise and leave the burrow, her offspring rapidly scrambles back into the pouch. Often, when the mother is grazing, the young wombat’s head appears between her hind legs, also grazing. In silhouette the wombat seems to have two heads, one at each end, both eating! When the mother moves from one patch of grass to another the young wombat’s head is usually above the place she has just left, and it eats where she has just eaten. It may be in this way that the young wombat forms the same food habits as its mother. By the time it is eight months old, the young wombat is a little more confident when it leaves the pouch. Now it moves short distances from its sleeping parent and even has some digging practice, scraping at the burrow 74

From birth to maturity

walls with its long sharp claws. In appearance the young wombat’s ears seem too large for its head which is still narrow, with a muzzle that is long and pointed in comparison with the short blunt snout of the adult. The rudimentary stub of a tail is still visible, adding to the young wombat’s underdeveloped look (see Figure 4.4).

The young at heel Although the mother’s pouch has expanded greatly since the tiny newborn wombat first entered it, there is a limit to this expansion and to the extra weight the mother can carry around. The muscle around the pouch opening, which has supported and held the large young, can no longer close the opening completely. Because the pouch has expanded more towards the anterior, its opening now faces towards the mother’s tail. Hence the pouch of the wombat is often described as ‘backward-pointing’, although this is only true when the large young is inside. Sometime between its eighth and tenth month the young wombat leaves the pouch permanently. By now it is eating a considerable amount of grass,

Figure 6.5 By 10 months of age the young has permanently left the pouch and is eating grass as well as drinking from the mother’s elongated teat.

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but it still also suckles from the elongated teat and may continue to do so until it is about 15 months old (Figure 6.5). During this period when the young is gradually drinking less and less milk and eating more and more grass and other plants, the bacteria necessary for the digestion of plant material in the animal’s colon become established. How the young wombat obtains these micro-organisms has not been recorded. Young koalas, at weaning, eat the mother’s soft faeces, which contain semi-digested material and bacteria from the mother’s caecum. Hand-reared wombats, if given access to scats from an adult wombat, will readily eat them from time to time. One wombat I handreared ate fresh scats dropped near the house by a semi-tame adult male on six separate occasions during the four months prior to weaning. Occasionally, when she first began to eat grass in some quantity, this young wombat would turn and eat the scats that she herself had just deposited. It seems likely that, in the wild, a wombat eats its mother’s scats in order to acquire its digestive bacteria. Little is known about the young wombat’s life during these months before weaning, but it seems likely that during this very vulnerable time in its life it spends much of its time in or very near a burrow, and it is almost always at its mother’s heels when she moves about. A mother with a small young at heel, probably about 11 months of age, was consistently found every night for a fortnight within 30 metres of an isolated burrow in the forest. She appeared to be feeding in close proximity to the burrow for two to three hours and spending the rest of the time in the burrow. A month later she was still feeding only 50 metres or so from the same burrow. The young wombat seemed to be very familiar with this restricted area; and if alarmed by a sudden sound, such as a falling branch or a squall of wind, it would bolt back to the burrow independently of its mother, which stolidly continued grazing, merely lifting her head to listen to her offspring’s panic flight. During the hours when I watched and listened to this mother and her young at heel, I often heard the soft ‘huh huh’, which is apparently a contact call; the young wombat generally made this sound when, after wandering a few metres from its mother, it turned to find her again (Figure 6.6). Occasionally, when it reissued from the burrow after a hasty dash from imagined danger or if it had strayed too far away, a sharper ‘huh’, better described as a ‘histle’, was given by the young wombat if it had temporarily lost track of its mother. This call was always answered by the mother with a softer ‘huh’, repeated until her offspring reached her. Once when I approached the young wombat too closely it took fright and gave a very 76

From birth to maturity

Figure 6.6 A young wombat giving the soft ‘huh huh’ contact call.

sharp, high-pitched cough. Immediately the mother came charging through the ferns towards us, but I did not stay to see how she would react to my presence, as I have no doubt that she would have been fiercely protective if she felt I had threatened her offspring. A wombat mother, like those of most other mammal species, is unusually bold and will confront any enemy that poses a threat to her as well as to her young. A potential predator needs to be very fast indeed if it is to seize and carry off a young wombat before being attacked by its angry parent. Foxes probably take small young at heel, but feral dogs and dingoes pose the chief threat to young wombats. During this very vulnerable time of its life, the young is always alert and much more ready than its mother to run for cover if a strange sound disturbs it. Its vulnerability may be one of the reasons why a young wombat will secretively deposit its scats in undergrowth, rather than displaying them as an adult does, as during the few moments it is defecating it is practically defenceless. During the two months after it leaves the pouch permanently, the young grows very rapidly, adding about 3.5 kilograms to its weight. At this time, 77

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(a)

(b)

(c)

Figure 6.7 A young wombat at play will throw itself on its side (a) tumble down a slope, rolling over and over (b), and toss its head and gallop back to its mother (c).

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too, as it gradually becomes more familiar with the area in the vicinity of the burrow, its confidence increases, and so does its playfulness. It will often intersperse its feeding and exploring with bursts of vigorous play. Wombat play is made up of several characteristic movements and attitudes performed in no particular order but with tremendous enthusiasm and exuberance. Typically, a young wombat signals the beginning of playtime by standing absolutely still with its front legs stiff and straight. Then it jerks its head and shoulders up, sometimes lifting its front feet right off the ground. Then, but not necessarily in this order, it tosses its head from side to side; jumps in the air with all four feet off the ground; rolls over on to its side; races off at a rocking gallop before coming to a sudden stop, reversing through 180 degrees on the spot and racing back to its mother, stopping or veering sideways just before the expected collision; lies flat on its stomach, head thrown back and swinging from side to side, lips drawn back in a wombat ‘grin’. If it is playing on or near a slope, it will sometimes run up the slope and roll down, tumbling over and over on its side (Figure 6.7). I defy anyone to watch a wombat at play without laughing aloud. As the young at heel explores the world beyond the burrow, it takes every opportunity it can to have some digging practice. Any hole or depression in the ground where earth is exposed will be investigated: stump holes where trees have fallen or burnt, rabbit holes, hollow logs and, most favoured of all, small minor burrows begun by other wombats but disused for some reason. Employing all the motions that it will later use in more serious excavations, the young wombat will dig enthusiastically, emerging occasionally to check on the whereabouts of its mother. Its long sharp claws gradually become shorter and blunter.

Weaning Between 12 and 15 months after birth, the young wombat is weaned, the mother’s milk supply gradually dwindling as the young eats more grass while needing less and less milk. The bond between mother and young usually remains strong and often continues for several more months (Figure 6.8). Mothers with older young at heel generally seem to pay their young little attention and it is probably the responsibility of the young to check on their mother’s whereabouts (see Figure 6.9 and Plate 19). An example of extraordinary maternal care was observed by Garry Smith and eight skiing companions in the Kosciuszko National Park: a wombat walking across the snow with her baby taking a ride on her back 79

Wombats

Figure 6.8 The bond between mother and young remains strong.

(see Plate 20). When the mother reached a patch of grass the young wombat climbed down and fed alongside her; after feeding, it climbed back on to the mother’s back and was carried off across the snow! It seems that this young wombat had found the easy way of travelling in the snow, even although it was not particularly soft as the mother only sank a maximum of about 10 centimetres in the softest sections. As far as I am aware this behaviour has not been previously recorded; any other sightings of wombats with ‘back young’ would be of great interest. The time taken to attain independence varies considerably. One young male was still at his mother’s heels nearly 11 months after weaning, but in some cases the association is broken soon after weaning.

Figure 6.9 It seems to be up to the young at heel to keep in contact with its mother.

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As the young wombat makes the transition from pouch life to independence, its digestive system has to adapt from a diet of low-lactose milk to one of high-fibre grasses. By the time it is weaned, the wombat’s digestive system, from one end to the other, is adapted to processing the coarse grasses that now constitute the major part of its food.

Mastication When the wombat is feeding, the two pairs of incisors grasp the grass stems, usually pulling them free without cutting them. The stems are then arranged in the diastema by the lips and tongue so that their ends are passed on to the cheek teeth, which consist of one premolar and four molars on each side of each jaw. These molar teeth have a flat surface, unlike those of other grazing animals. A kangaroo, for example, has two sharp ridges across the crown of each molar, which cut the grass stems as the lower molars are moved from side to side across the upper molars. In a study of the mastication of grasses by wombats, Kim Molina and Gordon Sanson found that the grass stems are reduced to small fragments in another way. There is a single sharp ridge of enamel on the cheek (labial) side of the lower molars and on the tongue (lingual) side of the upper molars. This ridge forms because the other side of each set of molars is free of enamel and therefore, being softer, wears away more quickly, leaving a sharp cutting edge on the opposite, enamelled side. The grass stems are first ground between the flattened crowns as the molars move sideways against each other and are then cut by the sharp enamel ridges as the lower ridge passes the upper one. This is a most efficient way of breaking up the tough, fibrous grasses that are the wombat’s dominant food. Because considerable force is applied to the molar surfaces as they are ground against each other, they are constantly worn down, but this is overcome by their continuous growth.

The digestive tract The wombat’s digestive tract also has several unusual features (Figure 6.10). In contrast to the majority of plant-eating animals, including most other herbivorous marsupials, the wombat’s stomach is very small. Its external appearance is simple, but internally a region of the mucosa (the mucous membrane lining the stomach wall) is organised into a specialised gland called the cardio-gastric gland. Ian Hume and other researchers 81

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Figure 6.10 The digestive tract of the bare-nosed wombat.

Redrawn from Hume (1982)

have found that this gland is distinctive because its membranous lining, which is folded into a number of sacculations or pouches, opens into the stomach cavity by way of 25 or 30 large crater-like holes. As the cells and tissues of this gland do not appear to be different from those in the rest of the stomach mucosa the functional significance of the cardio-gastric gland is not yet understood. In their studies on the digestive tract and digestion in wombats, Barboza and Hume found that lipids, proteins and soluble carbohydrates in the plant cell contents were digested and absorbed in the stomach and small intestine. The food passes from the stomach into the small intestine, which in an adult wombat is about three metres long. At the end of the ileum (that part of the small intestine nearest the large intestine or colon) is a very small 82

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narrow projection which forms the caecum. Barboza and Hume found that there were several permanent sacculations, near the junction of the ileum with the caecum. The most important feature of the wombat’s digestive tract is the colon, which is about four metres long. Barboza and Hume found that the lining of the first part of the large intestine (the proximal colon, which is about three metres long) was extensively folded, with two large permanent sacculations in an area about two-thirds of the way along its length. The proximal colon and the distal colon have a very large capacity – Peter Gowland found it to be about 68% of the total capacity of the stomach and intestines. The colon contains a dense population of bacteria. All parts of the gut also contain very large numbers of bacteria, but the numbers are three to eight times higher in the colon than in the stomach and small intestine. Experiments by several researchers indicate that these bacteria act on the food as it passes through the gut, breaking down the fibre by microbial fermentation. Perry Barboza and co-workers found that particles of food took an average of 49 hours to pass through the wombat’s gut, due mostly to a very slow passage through the colon, and their experiments indicate that the colon is a site of microbial fermentation and fibre digestion. The wombat is therefore classed as a hind-gut fermenter. The possums and the koala are also in this category, whereas the other members of the Diprotodonta, the kangaroos, are fore-stomach fermenters.

Scat contents The material that remains undigested after passing through the colon becomes the faeces or scats. These are excreted as roughly cube-shaped pellets, usually in groups of from four to eight pellets at a time. Microscopic examination of the material in wombat scats shows that they mainly contain fine fragments of leaf epidermis; usually fragments of several species of monocotyledonous plants are present in any individual’s scats. Also often present are fragments of leaf cuticle, xylem or conducting tissue and fragments of seed coats or testa. Most wombat scats I have examined contained large numbers of eggs of round worms or nematodes and, occasionally, the nematodes themselves. Traces of root and wood material are often present also. A few mineral grains and fragments of insect chitin and moth scales are sometimes found in wombat scats, but it is probable that the insects were accidentally ingested with the grasses and not eaten deliberately. 83

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Figure 6.11 A young wombat at 18 months of age, probably only recently independent of its mother.

Independence Once the young wombat becomes independent of its mother it must either find a vacant burrow or share one with another wombat willing to have a joint tenant, or it must dig one of its own (Figure 6.11). Probably it has already established at least one minor burrow where it can take shelter. Using a technique involving the use of genetic typing of hairs, Andrea Taylor and other researchers have developed a method of remote censusing. In this non-invasive method hairs are collected by placing strong sticky double-sided tape near wombat burrows. The hairs are tested in the laboratory and their DNA markers compared. Not only individual wombats can be identified by this method, but also their sex. This method has been used to show that it is the young female wombats of all three species that leave the natal area, rather than the males. This is the opposite of what usually occurs in mammals.

The young, mature wombat By the time the young wombat is two years old it weighs about 22 kilograms, although some are considerably heavier than this. It has changed markedly in appearance. The forehead and muzzle have broadened, and the ‘all ears’ 84

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look has gone, as the ears do not grow appreciably after 12 months of age. The whole body has become more thick-set, particularly the head and shoulders, and the fur is thick and glossy. Altogether, the young mature wombat is a sturdily handsome creature. It is at about this age that the wombat begins to display its scats by placing them in prominent positions instead of secreting them under cover. A home range has usually been established, and sexual maturity is fast approaching; the range must be ‘signposted’ at salient points with the wombat’s scent, so that the owner can move about confidently in an environment that holds its own particular odour. As a young female approaches her first cycle of sexual ‘heat’, called the oestrous cycle, her scats, conspicuously displayed and with pheromones attached, act as scent bearers and convey the message that she is approaching oestrus to any male that passes by. In areas where the wombats live in a cluster of burrows there is usually more than one male alerted by the female’s message, and fights between males often result. In less densely populated areas the female will wander beyond her usual home range, presumably in order to leave her sign where it is more likely to be encountered by a male. Most species of mammals have seasonal cycles of sexual activity, and in many marsupials this cycle occurs at the time of year which will ensure that the young emerge from the pouch in spring. As a wombat leaves the pouch at about nine to 10 months of age, this would mean that wombats would mate in late spring to early summer, giving birth about a month later. In the bare-nosed wombat, pouch young of all ages have been found at all times of the year. However, studies of this species in which the ages of a considerable number of pouch young have been estimated indicate that there are seasonal peaks in the time of breeding. In the highlands of New South Wales, most wombats give birth during the four months December to March, while in Tasmania Green and Rainbird found that, although births occurred at all times of the year, there appears to be definite bias towards October to January as a season for giving birth – 48% of births occurred in that four-month period. On Flinders Island, however, Green and Rainbird found evidence of seasonal breeding, as births occurred in the seven-month period between mid-January and the last week of August, with no births occurring in the other five months. Studies of the southern hairy-nosed wombat by Matt Gaughwin and others found that there is a definite breeding season, from July to December. Weaning occurs in late winter and spring and for enough high quality 85

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food to be available at this time there must have been good autumn rains to promote germination and to ensure the growth of grasses. If the autumn rains fail the grass will be dry and rank. Newly weaned wombats cannot cope with this food and many will die. It is also essential that there is adequate fresh, green grass throughout the summer so that the mothers can provide milk for the pouch young. It has been found that, if the young wombats survive for two years they are generally able to cope if there are drought conditions during their third year. This means that there must be at least two consecutive years of effective rainfall if there is to be an increase in the adult population. As there are many drought years in the areas where southerns live this increase rarely happens. The survival of the species depends on the adults living for many years so that they have some chance of successful reproduction. David Peters and Randy Rose studied the oestrous cycle in bare-nosed wombats and found that they are polyoestrous – that is, that they have a series of oestrous cycles during their breeding season, each cycle taking about 33 days to complete. By observing changes in the cells present in vaginal smears taken from the wombats, each cycle was found to consist of three distinct phases. The first, or pre-oestrous phase, occurs four to five days before the brief period, probably only about 15 hours, of oestrus or ‘heat’, during which ovulation occurs. The third phase, the post-oestrus, is of about four weeks’ duration. During their study, Rose and Peters also measured the wombats’ body temperatures, which showed the rhythm typical of nocturnal animals, with maximum temperatures occurring at night (from 9 pm to 6 am) and minimum temperatures during the day (from 10 am to 4 pm). However, they also found that other changes in body temperature occurred, which could have been related to the oestrous cycle. As the time of oestrus approaches, a female wombat becomes very active and aggressive, and during the brief ‘heat’ her urinogenital opening becomes moist and swollen. These signs have been observed in captive and hand-reared wombats. Mating has been observed in captive wombats; Graham Brown and Greg Young observed a mating between two captive bare-nosed wombats, the female attacking the male for about 30 minutes before allowing him to mate. During mating, which lasted for about 30 minutes, both wombats lay on their sides, the male holding the female around the chest. Similar behaviour has been seen in juvenile wombats during their play (see Plate 21).

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In the absence of reports of mating behaviour in wild wombats it was assumed that mating always took place in a burrow, and this is probably true of the hairy-nosed wombats, but Robert Taylor, observing bare-nosed wombats on pasture land in north-east Tasmania, saw behaviour that he interpreted as mating. Taylor observed two wombats moving around together, the male closely following the female, and several times putting his forepaws on her back as she kept moving. When he grabbed her back leg in his mouth the female lay on her belly. The male then lay on his side behind her, holding her rump between his legs. The female’s back leg was lifted up due to the position of the male’s body. The female stood up and moved away, dragging the male with her until he lost his grip. He then chased her again, and the sequence of grabbing her leg, stopping her, and lying behind her was repeated. When the male suddenly stopped holding her, the female rose and moved away. In 1990, using infrared equipment, Clive Marks observed and videotaped, courtship and mating behaviour in a pair of free-ranging wombats that was very similar to the incident described by Robert Taylor. Marks observed a pair of wombats on open pasture for 25 minutes, during which time a series of repeated behaviours took place. Courtship behaviour consisted of the male chasing the female while she trotted around in wide circles and figures of eight; periodically she would slow down, allowing the male to catch up with her (Figure 6.12a). After about two minutes of this chasing behaviour, the male delivered a powerful bite to the female’s rump (Figure 6.12b). At once, the female stopped running (Figure 6.12c); the male then grasped her hindquarters with his forelimbs, rolled her over on her side and mounted her. While they were copulating, the female rolled over into the prone position (Figure 6.12d). After several minutes, the female rose and broke into a half run, pursued by the male, and the chasing behaviour began again. Marks saw this sequence of behaviours – the chase in circles and figures of eight, the male’s bite to the female’s hindquarters causing her to stop running and allowing him to mount, the female breaking away from copulation to resume the chasing behaviour – repeated seven times over the 25 minutes. Although these are the only reports of wild wombats mating, the repetitive nature of the courtship and mating behaviour observed by Taylor and Marks seems to suggest that it is typical. The lack of other observations is easy to understand, as the observer must be in the right place at the right time with the right equipment. Bright spotlights, often used by observers,

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(a)

(b)

(c)

(d)

Figure 6.12 Courtship and mating sequence, as observed by Clive Marks. Illustrations: T Wright

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tend to make wombats move away to cover, but Marks’ infrared observation equipment, producing no visible light, did not disturb them. Once mating has occurred, the male plays no further part in the reproductive process. No kind of bond is formed between male and female, nor does the male have anything to do with the rearing of the young. If, following mating, the female becomes pregnant, her oestrous cycles cease and probably do not start again until some time after the young is weaned. None of the female wombats examined by Green and Rainbird showed evidence of pregnancy during lactation. Unlike kangaroos, which usually give birth to a second young as soon as one leaves the pouch, wombats do not appear to breed again until the young is fully independent. This can take as long as 20 months or more – one month of gestation, 8–10 months in the pouch and up to 11 months at heel. If the young becomes independent at about 15 months, which seems to be the average age, and the female breeds again almost immediately, she could rear one young every 16 months. In Tasmania, Green and Rainbird found that most females suckled their young for almost a year, and that weaning was followed by a period of rest; they concluded that the breeding cycle is longer than a year. McIlroy has some evidence that, if the mother dismisses her young at heel at an earlier age than usual, perhaps in response to good seasonal conditions, she may breed again and thus rear one young per year. McIlroy’s observations also indicate that a female may breed again soon after the early loss of a pouch young. All these factors probably account for the spread of the time of breeding. After the young has been weaned, some female wombats, of all three species, disperse to other areas. It has been suggested that this is a kind of maternal investment since it allows their burrows to be used by their offspring, who might have difficulty in finding a burrow of their own. Hair censusing has also shown that male southern hairy-nosed wombats are philopatric – that is, they tend to live close to where they were born. This is also true of the other two species.

The adult wombat Even after it matures sexually a wombat continues to grow slowly for several years, the body becoming even bulkier than before and reaching a weight of as much as 40 kilograms. The ears, which in the first year of life seemed so large, now appear almost too small for the great broad head (Figure 6.13). 89

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(a)

(b)

(c)

Figure 6.13 The changing face of the wombat. The same wombat is shown at eight months (a), at 18 months (b) and at four years of age (c).

Life-span Yet another detail of the wombat’s life history about which there is little information is its normal life-span in the wild. One wombat, tagged during John McIlroy’s study, was known to be at least nine years old. A handreared male wombat lived for at least 15 years in the forest near my home. Captive wombats have lived for as long as 30 years, but their average life expectancy is about 20 years. It seems reasonable to assume that, in the wild, a wombat should live for at least 15 years, provided, of course, that it does not succumb to any of the hazards which beset it.

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Plate 1 The northern hairy-nosed wombat is one of the world’s rarest mammals, found only in one small colony in central Queensland. Photo: © Dave Watts

Plate 2 The southern hairy-nosed wombat is found in parts of semi-arid country in South Australia. Photo: © Dave Watts

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Plate 3 The bare-nosed wombat’s range has declined drastically since European settlement.

Plate 4 A predominance of black hairs, some with gold bands, produces this coat colour. Photo: C Marks

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Plate 5 An ash-white bare-nosed wombat on the coastal dunes at Wilson’s Promontory in southern Victoria. Photo: M Schulz

Plate 6 The light grey coat of this bare-nosed wombat in Tasmania is stained by red clay. Photo: R Green

Plate 7 A brown bare-nosed wombat feeding on marram grass on the coastal dunes in southern Victoria. Photo: M Schulz

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Plate 8 Southern hairy-nosed wombats find weak points in the limestone shelf and dig through to softer ground beneath it. Photo: © Mark Newton

Plate 9 Many burrows of the northern hairy-nosed wombat are dug where the sand is soft and deep. Photo: A Horsup

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Plate 10 A wombat first loosens the soil with its front paws … then scoops out the loose earth. Photo: G Parker

Plate 11 The hind feet are used to push the earth away from the burrow as the wombat backs away. Photo: G Parker

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Plate 12 A dust-bathing wombat, scooping loose soil over its flanks.

Photo: G Parker

Plate 13 This bare-nosed wombat has dug a deep hole in the snow to find mat-rush leaves. Photo: I Pulsford

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Plate 14 The newborn wombat is only about 1.5 centimetres long. This tiny, embryo-like wombat is probably only about two weeks old. Photo: R Green

Plate 15 At six weeks of age the eyelids are still fused but whiskers have erupted. Photo: B St John

Plate 16 At two months the lips are well developed but still joined laterally, and firmly attached to the teat. Photo: C Marks

Plate 17 By the sixth month, fine fur covers most of the body; the nose and sole of the feet are still pink. Photo: G Parker

Plate 18 At about seven months the young ventures out of the pouch, but keeps close contact with its mother.

Plate 19 The young often remains ‘at heel’ for several months after weaning. Photo: © Dave Watts

Photo: © Dave Watts

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Plate 21 A pair of young wombats at play, in the mating position. Photo: V Merret

Plate 20 An unusual method of travel for a young wombat! This ‘back young’ was observed in the Kosciusko National Park. Photo: G Smith

Plate 22 A wombat suffering from sarcoptic mange. This is the wombat’s most serious disease; the weak, emaciated animal will die if it is not treated. Photo: P Helmore

Plate 23 Caring for an orphan wombat requires many hours, day and night, for several months.

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7 DANGERS, DISORDERS AND DISASTERS

E

very animal, in the course of its life, encounters difficulties and dangers. The wombat is no exception. Some of these adversities are part and parcel of the animal’s normal way of life; others are brought about by the actions of humans.

Injury and infection As it goes about its regular activities a wombat is likely to suffer some minor accidents and injuries. Claws broken while digging and cuts on the foot pads from sharp stones and thorns are probably common occurrences. The wombat’s habit of pushing its way through whatever lies in its path – thick undergrowth, tangled fallen timber and brushwood – rather than taking an easier if longer route, must make it prone to accidental sprains, breaks, cuts and abrasions, particularly as this bulldozing method of travel is often carried out at considerable speed. All these wounds, as well as those acquired while fighting or inflicted by dogs or dingoes, may become infected. The wombat appears to be highly susceptible to bacterial infections. These have been found to be hard to treat in captivity, but the wombat 99

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has its own ‘bush’ remedy, and that is to plaster the wound with a thick layer of earth. I have often seen a wombat with an open wound on some part of its body – head, rump, flanks or belly – deliberately lie down and roll in a patch of exposed earth, so that the soil sticks to the wounded area. Whether the resulting ‘mud pack’ has any healing properties I do not know, but it does serve as a fly-proof screen while the wound beneath it heals. Wombats suffering from mange also frequently plaster the affected areas with mud or clay in an attempt to relieve the intense itching of this disease.

Flood There are other natural hazards besetting the animals of the bush. Australia is not a kind land climatically, and every year, every season is likely to bring some kind of natural disaster to one or several parts of the wombat’s range. Flooding, as has already been mentioned, is one of the major disadvantages of burrow life. Most burrows collect some water in their entry way during heavy rain. In poorly drained soils this may make the burrow temporarily unusable, but rainwater rarely fills a burrow to the extent of trapping the occupant. However, burrows dug on the lower banks of creeks or rivers during dry or normal years are almost certain to be flooded at some time. Whether the occupants have sufficient warning to escape these potential death-traps depends on the rate at which the water level rises. A flash flood, caused by a sudden abnormally heavy downpour in the catchment area, can produce a rise of a couple of metres in a matter of minutes; if this happened in the daytime there would be little chance of escape for wombats sleeping in their burrows. Heavy rain can also result in the collapse of part of a burrow’s roof or walls. In any underground construction there is the risk of a cave-in, and wombat burrows probably have minor earth slips fairly frequently. During his explorations of burrows, Peter Nicholson often found small cave-ins ‘where the wombat could easily get out by climbing over the dislodged earth’; but during the winter he ‘found four burrows blocked by dirt and from only one of these did the wombat dig free’.

Drought Drought is another natural disaster that strikes the country fairly frequently. Well adapted to dry conditions as it is – living on the hardier, coarser 100

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grasses and drinking rarely – the wombat, nevertheless, can suffer malnutrition and even death from starvation during a prolonged drought, and during the winter following a drought, when a very limited amount of food is available. The breeding rate and successful rearing of the young declines sharply too, and a wombat weakened by malnutrition is more susceptible to other adverse factors such as attack by dogs and dingoes. The hairy-nosed species are particularly affected by drought in the semiarid regions where they live.

Fire Another scourge of the Australian bush is the forest fire. Every year, bushfires ravage thousands of hectares of wombat habitat, the eucalypt forests of eastern Australia. No doubt the wombat has a better chance of survival than most other forest animals. Often the floors of small valleys and gullies are unburnt, as a fire will jump right across the top of a gully

Figure 7.1 A few remnants of vegetation remained in this gully after a severe bushfire had swept through the forest.

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leaving the vegetation and animals untouched (Figure 7.1). But some bushfires are more intense; an uncontrolled wildfire rarely leaves a blade of greenery in its path. In December 1972 a severe and extensive wildfire ravaged the Nadgee Nature Reserve in south-eastern New South Wales. A study of the effects of this fire on 20 species of animals was made by a group of research workers led by Alan Newsome and including John McIlroy. They assessed the abundance of the larger animals by observing and counting their tracks on carefully prepared plots of soil, which were located at intervals along 40 kilometres of dirt roads, walking tracks and beaches. These counts, which were made before and after the fire, showed that while other large herbivores, the kangaroos and wallabies, survived poorly, wombats survived the fire well. Earth is a good insulator; G.E. Lawrence found that the temperature 15 centimetres down rodent burrows reached only about 72°C during a fire measured at 360–555°C, so it is likely that the temperature several metres down a wombat burrow would be relatively low. Newsome’s study showed an increase in the number of wombat tracks recorded after the fire, but this was probably due to the wombats feeding more often along the roads where grasses recovered well after rain. Although burrows provide some degree of safety during bushfires, an intensely hot fire will deprive the air of oxygen so severely that even the wombats deep in their burrows suffer and a number die. Some of the burrows themselves are completely destroyed in a severe fire, especially those dug beneath uprooted trees; when these burn, the whole structure usually collapses. When fire destroyed 221 000 hectares of forest in East Gippsland in 1983, part of the coastal forest adjacent to my home was burnt out. Before the fire there were nine frequently used wombat burrows in 80 hectares of this burnt area, which were used by at least four different wombats: a large female, two smaller wombats of unknown sex and a hand-reared male, then seven years old. All of these wombats also sometimes frequented a part of the forest that was not burnt, and had other burrows there. On checking the burrows in the burnt area a few days after the fire, I found that three of them had been destroyed: two, dug under old fallen logs, had collapsed at the entrances and for some distance along the tunnels as the logs burned; the third had been flattened by a fire-fighting bulldozer. All of the wombats had disappeared; the hand-reared male was seen shortly after the fire in the unburnt forest, but the others were not seen again. It is not known whether they died in the fire or left the area completely. 102

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Some wombats do survive even the hottest fire, only to emerge to find a completely changed world. All the familiar features of the wombat’s limited landscape have gone; all familiar scents and signs have been eliminated. Worse still, so has most of the food – the grasses that form the major part of the diet have been reduced to grey ash. If the fire has devastated a large area, and wildfires usually do, the nearest green food source may be many kilometres away, well beyond the wombats’ usual limits. Some of them manage to exist by eating roots and bark; and when rain falls, fungi of many kinds usually appear before the grasses and herbs begin to grow, providing another temporary food supply. Other wombats travel long distances in search of food, encountering more dangers as they do so. Wombats living nearer to the perimeter of a bushfire have a better chance of survival, but if they move into new country they are not welcomed by any wombats residing there, and the resulting fights can be savage and harmful.

Humans – the worst enemy Although all these natural conditions that expose the wombat to risk of injury may be harmful to individual animals, they have never eliminated the species from any large area. Only the actions of people over the last 200 years have managed to do this. Since the first days of European settlement, wombats and humans have come into conflict. Wherever land was cleared, wombats were killed, usually by poisoning or shooting. However, it was not until the introduced rabbit spread across the land, forcing landholders to erect wire-netting fences, that the wombat became thought of, and treated as, a pest to be eradicated ruthlessly. In Victoria, for instance, the bare-nosed wombat was gazetted as vermin in 1906, and in 1925 a bounty system was introduced. Under the system, trappers employed by local councils and subsidised by the government were paid a bounty of 10 shillings ($1) on each wombat scalp they collected. Wombats were trapped, and poisoned and shot, in enormous numbers. During the last 16 years in which the system was in operation, 64 000 wombats were destroyed by bounty hunters. They were killed not only on and near farm land but also deep in the forests where they were doing no possible harm to anyone. Trapping was the usual method used to collect the ears and scalp for which the bounty was paid. Heavy steel traps had strong metal jaws which, when the trap was triggered, snapped around the animal’s foot or leg and held it tightly. These traps, lightly buried in the entrances of wombat 103

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burrows and on their trails, held the wombat until the trapper returned to check his traps, which was often a week or more later. Meanwhile the wombat, its leg broken by the trap, had probably died after enduring days of pain, exposed to the daily extremes of heat and cold and at the mercy of possible attack by predators. The bounty system remained in force in Victoria until 1966; but even when it was removed, wombats were still classified as vermin under the Wildlife Act so that, by law, it was obligatory for landholders to destroy any wombats on their property. Fortunately, many farmers were tolerant of the wombat – so long as they didn’t lose any money on its account – and as the law was not strictly enforced, wombats still inhabit many areas on and near private land. In 1977 the wombat was declared ‘protected wildlife’ in western Victoria, with the threat of severe penalties for scalp hunters, but it was still classified as vermin east of the Melbourne to Albury railway line. As by that time there were very few wombats left in western Victoria, this legislation was almost redundant. The Victorian Wildlife Act was altered again in 1984 when at last the shameful law that proclaimed one of Australia’s unique native animals as vermin was repealed. Instead, the wombat was declared ‘protected wildlife’ in most of Victoria. Due to considerable pressure from some farmers’ groups, it was simultaneously declared to be ‘unprotected wildlife’ in certain specific areas – a total of 193 parishes – in eastern Victoria, where wombats were said to be causing problems to landholders (Figure 7.2). In these parishes landholders may take or destroy wombats ‘by the use of fumigants, traps or firearms only on freehold or leasehold property or on Crown land within one kilometre of such property’, except where the Crown land is also part of a national park, where wombats are fully protected. In the rest of Victoria, and in the whole of New South Wales and Tasmania, where wombats have been protected since 1974 and 1971 respectively, landholders can apply to the wildlife authorities for licences to allow them to reduce wombat numbers by killing some where they are causing damage and their destruction is necessary to relieve the situation. A similar situation occurs in South Australia, where massive land clearing for agriculture and the damage and competition caused by large rabbit numbers have caused a decline in the populations of southern hairynosed wombats. The total population was estimated to be about 330 000 animals in the late 1990s. Only about half of the areas they occupy are in reserves, such as National Parks and other conservation areas. A plan of 104

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Figure 7.2 Wombats and their burrows can be a problem to farmers.

Photo: D Fanning

management, compiled by Barbara St John and Glen Saunders in 1989 and implemented by the Department of Environment and Heritage, monitors the populations on private land as well as on the reserves. While all these wombats are now protected by law, permits are still issued to landholders who can show that the burrowing and grazing habits of wombats are affecting their livelihood. Every year since 1987 approximately 1000 southern hairy-nosed wombats have been destroyed under this permit system. Human impact on the northern hairy-nosed wombats has been catastrophic. It was probably never a common species, but the decline over the last 200 years has brought this wombat to the point where it is critically endangered. Overgrazing by cattle and sheep, in combination with drought and predation by dingoes are the main factors causing this decline. A recovery plan for the northern hairy-nosed wombat, prepared by Alan Horsup and his team, aims to encourage the wombats to reoccupy more of Epping Forest and increase their numbers there, and recently there have been encouraging results. Recent remote censusing in the Epping 105

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Forest colony shows that there has been an increase in numbers, from about 115 to 138, only 28 of which had ever been trapped. This indicates that there are now a large number of young wombats in the population, which is most encouraging news. There is also a significant difference in the sex ratio – females were outnumbered 2.5:1 by males in the mid 1990s when the population contained only 65 individuals but hair censusing now indicates the sex ratio is nearly even. The wombats are now found in about one-fifth of the 3300 hectare park, a major expansion of 100% in the last two to three years. It is thought that the dingo fence has been the major factor in these increases, not only lowering predation but, because females tend to disperse when they are mature it is probable that they were being lost to the population by leaving the park in search of new habitat, which, of course, they never found, and consequently that they perished. The dingo fence now prevents them from leaving the park. Plans are being made to translocate a small number of northern hairynosed wombats to another location in 2009. A two year search for a new site was carried out, across central and southern Queensland, and a property near St George, 600 kilometres to the south has been selected for its suitability for these wombats. A second breeding colony will help to protect the species from possible extinction which could be caused by a single severe event such as disease or fire. Climate change is also a looming danger to all wombats. Any increase in the frequency of drought will have a devastating effect on their ability to breed and the likely increase in wildfires will pose a danger to all wombats.

Protection or control? In spite of the protection laws, the attitude of many farmers towards wombats is still the same: they see them as vermin to be destroyed by any means. And some of the means they use are not pleasant. The execrable steel-jawed traps are still, often illegally, set to catch wombats, but more often these days burrows are fumigated with chloropicrin or phosphine gas, in the form of Larvacide or Phostoxin, two commercial preparations used in the destruction of rabbits. Chloropicrin is also known as ‘tear-gas’ because it causes intense irritation of the eyes and respiratory tract. Phosphine gas is a systemic poison. Symptoms of phosphine poisoning in humans include nausea, abdominal pain, headache and convulsions with 106

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ensuing coma. It is not known whether other mammals experience similar distressing symptoms before death, but it seems likely. Death by gassing with these preparations may not be as barbarous as the slow death of the steel-jawed trap, but it is still cruel. In a review of the management techniques for the bare-nosed wombat, Clive Marks found that in cases where the destruction of individual wombats is required, burrow fumigation using carbon monoxide as the fumigant is the most humane and target-specific method. Shooting was found to be the second most common technique used by farmers in a survey in north-east Victoria, where it was used by 68% of the 113 landholders surveyed. Whether death by shooting is humane or not depends on the skill of the shooter and the efficiency of the firearm used. Also, if the wombat is in a trap a close shot to the head may be an appropriate method of destruction, but it is less likely that a humane death can be assured if the animal is unrestrained and distant from the shooter. Spotlight shooting is considered a sport by some weekend shooters and in some areas wombats are in double jeopardy if they feed on roadsides. They not only run the risk of becoming a road kill but are considered easy prey by these ‘sportsmen’. Cage traps are occasionally recommended by wildlife authorities for the capture of wombats, which may then be shot or transferred to national parks and other forest areas away from pastoral land. It is a method open to abuse and its use by untrained persons is questionable. Cage traps have been found to cause injury to claws and noses as the wombats try to escape, and death can occur if the caged animals are exposed to heat or cold. Translocating wombats is also a doubtful practice, as unless a release site is very carefully chosen, they are likely to be severely harassed, even killed, by resident wombats. In fairness to the farmers who consider wombats to be pests, it must be admitted that there is a need for controlling wombat numbers where they are a nuisance. In spite of the effects of myxomatosis and 1080 poisoning campaigns, rabbits remain plentiful throughout most of the wombat’s range in eastern Australia, and netting fences are still used to exclude them, not only from farmland but also from young pine plantations, which are very vulnerable to attack by rabbits. A wire-netting fence, however, erected at considerable cost to keep rabbits out, presents only a temporary barrier to a wombat, which either simply pushes a hole through the netting or digs underneath it. To do this, the wombat scoops out a shallow trough under the fence, then pushes its head under the wire to lift it up so that the 107

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Figure 7.3 A wombat digging under a fence of wire-netting will eventually create a sizeable hole. Photo: C Marks

broad shoulders and neck can squeeze beneath it (Figure 7.3). Then it stands up, bending the wire as it does so and making a sizeable hole under the fence, and walks through into the crop or pasture or pine plantation or vegetable garden or anywhere else that suits it. The wombat usually rambles some distance from its point of entry, so when it leaves it makes another hole. The number of wombats using a pasture is often overestimated. As each individual wombat produces about 100 scat pellets every night, and these are usually deposited in prominent places, an area used by even just one wombat can soon be well sprinkled with wombat sign. In addition, wombat scats have a slow rate of decay, especially in cold dry weather, so that the number of scats lying in a pasture, or along a track, can give the impression that the density of wombats in a certain area is much greater than it actually is. Although it may eat some pasture grasses, the wombat does little, if any, economic damage to pastures, crops or plantations, and it has no interest at all in vegetables; however, the holes it makes in fences not only let rabbits in but also let domestic stock out. Other animals such as wallabies, 108

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kangaroos and pests such as wild pigs can also use the holes; and if the farmer mends these holes, the wombat simply makes others somewhere else. It is not surprising that many landholders have a very low regard for wombats, but there are some who, instead of trying to destroy them, are countering the problem by installing ‘wombat gates’ or electric fencing. For many years, farmers in Europe have built swinging gates that allow badgers to pass through fences. Like the badger, the wombat regularly uses the same trails and the holes in fences along these trails. If a solidly constructed gate, swung from the top, is placed at one of these holes, while at the same time other holes nearby are repaired regularly, the wombat can be trained to use the gate. The wombat can move freely in either direction, but lighter animals such as rabbits are excluded because they cannot push the heavy gate (Figure 7.4). In a management study in southern New South Wales, Philip Borchard installed wombat gates in an existing fence and installed motion sensing cameras. Over a period of a year he obtained many photographs of the wombats using the gates, and of other animals being foiled by them (Figure 7.5). It has been found that wombats will use gates placed up to 800 metres apart in preference to making new holes. However, where wombats have access to improved pasture from surrounding bushland, their numbers increase and hence the level of movement between the bush and the pasture also increases. The commitment required by the landholder to establish and maintain wombat gates is such a drawback that this method becomes impractical. Also, as many landholders want to eliminate wombats from their land, a method which allows unrestricted access is not likely to be accepted. The installation of electric fencing is a more practical method of excluding wombats from pasture, crops, plantations or anywhere else they are not wanted. The rising cost of fencing has prompted the development and greater use of electrified fences. These have proved to be economical and effective in controlling livestock, and they are also increasingly being used in conjunction with existing netting fences in wildlife control. Clive Marks experimented with a two-wire, earth return electric fence, constructed on the bush side of an existing netting fence that was adjacent to pasture. The electric fence was built as a free-standing structure positioned 40 centimetres from the existing netting. The lower energised wire was about 10 centimetres from the ground while the upper wire was about 20 centimetres high. Marks made visual observations of wombats interacting with the electric fence, using infrared observation equipment. He found that wombats, which had previously dug under the netting fence, 109

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Figure 7.4 A wombat gate in a netting fence allows wombats to pass through without damaging the fence.

reacted immediately to contact with the energised fence by withdrawing and moving at a fast run back to a burrow in the bushland. A second, more cautious investigation of the electric fence was made by the four wombats Marks had identified in this study, with the same result – they immediately retreated to burrows in the bushland. Some wombats, after receiving a previous shock at the electric fence, attempted to charge through the fence at places where holes had previously existed, but they also retreated immediately when they received another shock. The netting fence slowed the charging wombats and kept them near the electrified wires; without this netting barrier, Marks felt that the wombats would probably succeed in charging through the electric fence. Marks found that the wombats appeared to learn rapidly to avoid contact with electric fences, and that this learned behaviour is retained for a significant period. Thirteen weeks after his study began there were no signs of digging under the electric fence. 110

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Figure 7.5 This heavy wombat gate was no problem for a wombat but other animals were excluded. Photo: P Borchard

As well as damage to fencing, some landholders also blame wombats for the erosion of creek and river banks. Occasionally, after periods of very heavy rain, low level burrows may be flooded and cave in completely, slightly altering the shape of the bank and the stream flow. However, the amount of erosion damage caused by wombats is infinitesimal compared with that caused by poor farm management – overstocking and overclearing in particular. Unfortunately, wombats will often choose to burrow where slopes such as creek or river banks have been exposed by the clearing of the natural vegetation; any resulting erosion is blamed entirely on the wombat, which has only slightly aggravated a situation originally caused by the landholder.

Poisoning Rabbits are indirectly responsible for another hazard encountered by wombats and other native animals. Since the late nineteenth century, poisons such as arsenic and strychnine have been added to grains, mainly oats and wheat, and spread widely. These poisoned grains have killed not 111

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Figure 7.6 A dingo’s paw caught in a steel-jawed trap. These barbarous traps also catch many non-target animals, including wombats. Photo: P Stevens

only millions of rabbits, but also untold numbers of grain-eating mammals and birds: wombats, wallabies, kangaroos, pademelons, potoroos, possums, magpies, currawongs, emus, quail – the list is long. For the last 30 years or so, the poison generally used in rabbit poisoning campaigns has been sodium monofluoroacetate, generally known as ‘1080’. This poison is added to baits such as diced carrots, oats and pellets of compressed bran and pollard, which are either laid along shallow furrows on the ground or spread from an aeroplane. Although the method is successful in helping to control rabbits, some non-target animals – native mammals and birds – also die from eating the baits. Most herbivorous marsupials are highly sensitive to 1080 poison, and some are even more sensitive than rabbits. However, other factors such as the amount of bait taken, the concentration of 1080 in the bait, the weight of the animal and its readiness to eat the carrot, oats or other poisoned bait, also help to determine the actual risk that an animal faces of consuming a lethal dose of the poison. The wombat’s bulk makes it less susceptible than small marsupials like the potoroos and pademelons, but nevertheless wombats are killed during rabbit-poisoning 112

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campaigns. The numbers of wombats so killed are extremely difficult to assess, as they mostly die in their burrows, and those that die above ground are often in thickly forested country. 1080 poison is also used in wild dog and dingo control, but meat baits are used in this case and these baits are unlikely to be taken by herbivorous animals such as wombats. On the other hand, the control of wild dogs by trapping, using steel-jawed traps, kills more non-target animals than it does dogs and dingoes (Figure 7.6). In one four year period (January 1979 to December 1982) nearly twice as many native mammals and birds were killed in dog traps in Victoria as were dogs and dingoes, and 3112 of these were wombats.

Land clearing None of the control measures directly or indirectly affecting wombats – trapping, shooting, poisoning, or all three combined – has had as much impact on wombats or Australia’s other native animals as the clearing of the land itself. This process, which began 200 years ago, continues today unabated. Large expanses of forest are still being cleared for crops and grazing, for timber production and pine plantations (Figure 7.7). More forest disappears as towns expand and roads are widened and proliferate throughout the country. In the mountains and hills that comprise most of the wombat’s habitat, clearing for grazing creeps higher and higher up the slopes; clear-felling for wood-chipping or timber-harvesting and for the planting of pine trees destroys more and more of the native forests. The number of burrows that remain undamaged after a clear-felling operation, whether for grazing, forestry management or pine-planting, depends mainly on the terrain. Fortunately for the wombat, which often digs its burrows on the banks of creeks and rivers, no clearing can legally be done on the slopes adjacent to stream beds, to reduce the risk of erosion – the prescribed distance varies from 20 to 200 metres, depending on the type of stream and the vegetation – so burrows on these slopes and on others too steep for the bulldozers, will be unscathed. In areas where there are no such inaccessible places, the destruction of burrows will be total. There have been two studies, made almost 20 years apart, of the effects on wombats of clear-felling native eucalypt forest and replacing it with pine plantations. In his study conducted in 1970 and 1973, John McIlroy found that the population densities of wombats living in the pine plantations 113

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Figure 7.7 Large areas of native forest a still being clear-felled to make way for pine plantations. After removal of the timber, what is left is pushed into windrows, ready for burning. Photo: M Schulz

dropped initially during the felling and burning of the native forest, then increased again so that in the three to five year old pine plantations densities were near the levels previously found in the native forest. This increase was due, at least partly, to the regrowth of grasses between the young trees. Fewer wombats were found in older stands of pines, however, where lack of sunlight caused by the closed canopy of the trees, as well as a dense litter of pine needles, had resulted in greatly decreased growth of grasses and other forest floor vegetation. Densities increased again slightly after the first thinning, 15–16 years after planting, but they never reached the densities in the native forests, and just prior to the final felling at 35–40 years, wombat densities in the plantations were dropping again, to about a third of the number in the native forests. In a similar study in 1990, Carol Rishworth recorded much more drastic changes in wombat density. Once again there was a decline in densities in clear-felled areas but numbers recovered in plantations that were more than one year old. In a six year old plantation the numbers were even greater than in the eucalypt forest areas, but then densities plummeted to zero in all of the three 15 year old plantations surveyed. Once the plantations were thinned, however, densities increased again and in 20 and 25 year old plantations they were similar to those in native forest. These changes are 114

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probably due to modern thinning techniques and heavier machinery, which open up the canopy to a greater degree, crush the debris more and disturb the soil surface more than the methods and machines used 20 years ago. Although the modern machines disturb the ground to a greater extent and hence could destroy more burrows, they probably also stimulate increased growth of grasses by removing or destroying other ground cover. The results of McIlroy’s and Rishworth’s studies show that although wombats can survive replacement of their native forest by exotic pines, their numbers in the plantations are often low. They also indicate that changes in forestry methods, such as earlier and more frequent thinning, could benefit wombats and other wildlife. The position is initially the same where native forests have been logged or clear-felled for wood-chipping: if enough burrows and food remain, the wombats can maintain a hold on the area. However, usually these logged or clear-felled tracts of land are subjected to ‘high-intensity regeneration burning’. These ‘slash burns’ are carried out in order to remove logging debris, to prepare a receptive seed bed for new regrowth, to ensure the maximum germination of seeds of the eucalypts, and thus to promote the regeneration of the forest for future harvesting. These extremely hot ‘controlled’ fires destroy all the existing vegetation, and hence all the wombats’ food; in any case, wombats are unlikely to live through fires of this intensity. Where land is cleared for crops or grazing, generally all wombat burrows are destroyed – work that has been made easy by the advent of the bulldozer. Some wombats may attempt to re-establish themselves, or at least to enter the cleared land and feed on its usually improved pasture. Here they are likely to come into direct conflict with farmers and graziers, particularly, as has already been discussed, in areas where rabbits are a pest – then out will come the traps and poisons and guns.

Road deaths Wombats face other hazards that are less deliberately brought about by people but that are nevertheless due to our presence in the land and our treatment of it. Large numbers of wombats are killed on the roads in southeastern Australia, and it would probably be true to say that the only wombat the majority of Australians have ever seen is a dead one, its tumbled body lying beside a road or highway (Figure 7.8). Wombats that have been passing from one part of their home range to another for years will not 115

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Figure 7.8 A sight that is all too common beside our roads and highways. Photo: M Schulz

alter their habits simply because a road has been constructed through their forest. Even long after a road has been established, they will amble across it as though it is just another open space in the forest, although they will use culverts if these happen to lie in their path. To add to the hazard, they are often attracted to roadsides to graze on some of the grasses and clovers planted there to stabilise the ground. After rain, when there is fresh growth along the roadsides, wombats are killed in even greater numbers than usual. Following bushfires, too, when roadside grass is often the only green food left in a burnt area, the number of animal casualties increases markedly. Wombats are easy prey for spotlight shooters at any time, but especially so when they are grazing beside a road.

Predation Although a wombat is almost completely helpless against the predations of humans, it does have some defences against the other introduced predators that beset it: wild dogs and foxes. Domestic dogs have been deserting their human masters, and humans have been dumping 116

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unwanted dogs and pups in the Australian bush ever since the first colonists brought dogs to the country. The abundance of marsupials, both large and small, around the early settlements would have provided them with an easy living; but they became a nuisance when the bush and the marsupials were cleared to make way for sheep and cattle, and they are still a major problem in many areas. Cross-breeding between feral dogs and dingoes has produced a motley horde of wild dogs. As mentioned in Chapter 1, the dingo probably came to this country with a late immigration of Aborigines about 3500–4000 years ago, and on the mainland it gradually replaced the thylacine, the only marsupial carnivore of comparable size, and the smaller Tasmanian devil. Wild dogs and dingoes not only kill stock; they also slaughter native animals of all kinds in untold numbers, and at or near the top of the menu in south-eastern Australia are two of the slower-moving marsupials: the swamp wallaby and the bare-nosed wombat. Dingoes are known to have killed nearly 10% of the small population of northern hairy-nosed wombats in 2000–01. A dingo-proof fence has since been built around all the wombat habitat in Epping Forest National Park. It seems from my observations that every individual wombat has to learn that wild dogs and foxes are potential enemies. None of the young wombats I have reared has shown any instinctive fear of dogs and foxes, either of their barking and howling or of the scent of their scats and urine. Nevertheless, the wombats’ awareness of the possibility of attack by a predator is shown by the fact that they are instantly alert at the sound of a footfall or at any other slight sound in the bush that may spell danger. A wombat grazing in a forest clearing, or trundling along a track, or even sitting drowsing near its burrow, is deceptively unconcerned; at the slightest hint or crackle of danger it is instantly alert and often running for cover. Escape to the nearest burrow, crouch slightly with the broad reinforced rump presented towards the entrance, give a powerful thrust upward or sideways if anything – a predator’s head, a human hand – touches the rump, and crush it against the roof or wall of the burrow: the method is very effective, provided that there is a burrow or similar refuge nearby and that the wombat can reach it before being attacked. Caught out in the open, a wombat is not defenceless either. Its powerful jaws can deliver a crushing bite; the long, forward-pointing lower incisors, driven at an enemy in a stabbing lunge, can inflict deep and severe injuries. An adult wombat in good health can usually hold its own against a single dog, but it has little chance against a pair and none at all against a pack. 117

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Foxes were originally brought out to Australia in the mid-1800s to provide sport for several hunt clubs. Later, in the 1870s, foxes were deliberately released in Victoria, and they gradually spread over the rest of Australia. There are now very few places on the mainland where they are not found. In 2000 there were rumours that foxes had been introduced into Tasmania and this has since been proved to be true. Several scats have been positively identified as fox, using DNA techniques. At first, foxes were hailed as the answer to the rabbit problem, but their love of poultry and lambs caused a bounty to be put on them; since early this century they have been declared vermin in all states. Foxes do not eat just rabbits and chickens and lambs, however. They will eat almost anything that lives – plants, insects, frogs, fish, lizards, birds and mammals – and carrion of all kinds. They can chase and kill animals much larger than themselves – there is a report of a fox attacking and killing a euro – and there is no doubt that they sometimes kill wombats. Young at heel and newly independent immature wombats would be the easiest prey; old or weakened adult animals would also be vulnerable. The crushed skulls of foxes have also been found in wombat burrows, so obviously the wombat is sometimes the victor.

External and internal parasites Almost all mammals, both wild and domestic, are host to various internal and external parasites. Many of these parasites are harmless, but some may be detrimental to the animal’s health. When Europeans first brought out their sheep and cattle, pigs and goats, camels, donkeys, deer, dogs, cats, foxes, rabbits – the full list is formidable – they also unwittingly brought a whole new spectrum of parasites and insect pests. The native marsupials undoubtedly carried parasites of various kinds long before Europeans arrived, but they had much less resistance to the new imports. The diseases that affect the wombat most severely are all caused by parasites originally carried by introduced domestic animals. Several kinds of external parasites have been found on wombats, including fleas, lice, mites and ticks. It is a mite that gives rise to the wombat’s most serious disease: the condition known as sarcoptic mange. The mange mite, Sarcoptes scabei, burrows into the skin where it lays its eggs and causes intense irritation. The wombat scratches and rubs to relieve the irritation, and hair loss results, followed by crusting and scabbing of the skin, especially on the head and ears. In severe cases the 118

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eyes may be virtually closed by the lesions, and the animal loses most or all of its hair, the bald skin becoming wrinkled and thickened (see Plate 22). The wombat’s vision and ability to eat are severely affected, and it becomes weak and emaciated and eventually dies. Mange is prevalent in both bare-nosed and southern hairy-nosed wombats but it has not been found in the northerns. Whether the sarcoptes mite came to this country with the dingo about 4000 years ago, or with domestic dogs and foxes in the last 200 years is not known – probably both, as it infects wolves (the dingo is an Asiatic wolf) as well as dogs and foxes. A wombat contracts mange either by contact with an infected wombat, or by being exposed to a large quantity of mites in a burrow. Casual burrow-sharing is not thought to be the means by which mites are transferred from one animal to another. Mites can only live for a maximum of three weeks off a host, so burrows are unlikely to harbour them in large numbers unless an infected wombat has recently died in the burrow. Skerratt’s work showed that whether wombats will develop clinical signs of mange or not depends on the number of mites they are infected with, and that perfectly healthy wombats will contract the disease if they are exposed to a large number of mites. He also showed that mange can be treated effectively. He found that when infected animals were treated with three injections of Ivermectin, 300 micrograms/kg, 10 days apart, all signs of the mange disappeared. However, the mites were not entirely eliminated until the wombats received a second regime of treatment. (Further information about the treatment of mange is given in Appendix 2.) Other mites commonly found on wombats are the earmite Raillieta australis and the skin mite Acaroptes vombatus. Skerratt, in a study of parasites and diseases of the bare-nosed wombat, found that these mites, and the common wombat tick, Aponomma auruginans, were not found on wombats suffering from sarcoptic mange but were common on those without mange. Although wombats living near the eastern coast of Australia appear to have developed immunity to the paralysis tick, Ixodes holocyclus, which infests that area, they are plagued by the common wombat tick and several other species of ticks. A severe tick burden, which can cause anaemia, can weaken a wombat to the point of killing it. Even the wombat’s vigorous scratching often will not dislodge an embedded tick. A female wombat has an added discomfort, as these bloodsucking parasites often establish themselves on the outer rim of her pouch, and occasionally even inside it, 119

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being attracted by its warm, moist skin, and she is virtually helpless to remove them. As well as ticks there are many other external parasites that also visit their host, feed and then leave. Mosquitoes, sand flies, march flies, louse flies and other bloodsucking insects all harass the wombat, both inside and outside the burrow, although it escapes some of their depredations by being mainly nocturnal. Blowflies of both native and introduced species attack any animal with an open wound in order to lay their eggs, which hatch into maggots and feed on the raw flesh. The wombat’s habit of coating its wounds with a ‘plaster’ of soil gives it some protection against these pests, but it is still vulnerable to fly strike. Like the majority of animals, the wombat is host to several internal parasites such as worms of various kinds. Most of these, if present in small numbers, apparently do the animal little or no harm. Thick white roundworms are common in the colon of the wombat, and smaller roundworms have been found in the walls of the small intestine and in various organs, such as the lungs. Several harmless species of tapeworms are occasionally present in the intestines, but the wombat is not a host for hydatid cysts. Wombats grazing in areas where sheep have also grazed are susceptible to a more serious internal parasite. Liver fluke is a relatively common parasite in sheep, and wombats with severely affected livers have been found. Pasture contaminated by domestic stock is also responsible for the disease called leptospirosis, but in this case cattle are the principal hosts. Sheep, goats, pigs, dogs and rats also carry this infectious bacterial disease, which may be transmitted to man through the excretions of infected animals. In wombats, which probably acquire leptospiral infections when grazing on swampy pastures, the disease causes serious kidney damage. The cysts of other disease-causing parasites such as coccidia have been found in young wild wombats; a major cause of death in hand-reared and captive wombats is toxoplasmosis, in which the animals become infected by accidentally ingesting the microscopic toxoplasma oocysts. These cysts are often passed in the faeces of cats, particularly kittens. The disease develops suddenly and severely, the animals showing almost no symptoms before collapsing and dying. Toxoplasmosis is undoubtedly carried by feral cats as well as domestic ones, so wild wombats also are at risk of acquiring it.

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Other diseases Diabetes, arthritis, cancer, asthma and pneumonia are other diseases that have been detected in wombats, and no doubt there are other physical disorders which affect them. This aspect of the wombat’s life, like so many others, has not been studied in detail.

Wombats in balance with their environment As this chapter has shown, humans are responsible for most of the dangers, disorders and disasters affecting the wombat. Unlike rabbits, sheep, goats and the other introduced animals, which can overgraze the areas in which they live, causing erosion and other problems, wombats tend to live in balance with their environment. When conditions are good, breeding rates increase; but because of their social organisation, wombats do not overcrowd the area they live in – there is still dispersal of surplus animals. Although there may be an increase in the density of wombats in a particular area in a good season, during bad years breeding rates decline and mortality increases. Thus, for tens of thousands of years, wombats have regulated their population. In spite of all that European people have thrown at them, wombats still maintain a dynamic balance with their environment.

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8 WOMBATS IN THE WARDROBE

‘H

alf the people in Australia own a wombat or have a nodding acquaintance with one – and the other half want to,’ wrote one wombat owner. He had found, as many have found before and since, that wombats are very special animals; and while he exaggerates the case, it is true that an increasing number of wombats are finding their way into human homes and lives. Most of them result from road kills; when a wombat or other marsupial is killed on the road there is always the chance that it is a female with young in the pouch, and more and more motorists are becoming aware of this possibility. The result is that many orphan marsupials are being rescued and hand-reared by humans. By law, all orphan marsupials should be taken to the appropriate wildlife authority, whose officers will send them either to established wildlife refuges or to individuals they know to be competent – and willing – to care for them until they are ready to be returned to the wild. This is not always done, however, and often people who are well intentioned but ignorant of the special needs of young marsupials attempt to rear them. (See Appendix 2: Hand-rearing orphan wombats.)

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The totally dependent orphan Many of these orphans die – stress, insufficient warmth and incorrect diet being the main causes of death. Kangaroo and wallaby joeys are particularly sensitive to stress, but wombats are tougher, and a surprising number survive the shock and distress of being suddenly and often violently dislodged from the dark, warm closeness of the pouch and exposed to the bright, noisy strangeness of a human’s world. Barking dogs, children’s inquisitive fingers, looming faces – it does not take much imagination to appreciate the terror a newly orphaned animal must experience, but a young wombat will usually adapt to them all with remarkable rapidity. It will, of course, have a much better chance of survival if at least some of the details of its normal development and way of life are known. It is adapted to an environment that is completely temperature controlled, with food available on demand, so it must be provided with a warmed substitute pouch and frequent meals of a low-lactose milk if it is to thrive. A young wombat is a delightful creature – intelligent, playful and affectionate. It loves, or rather demands, human company, preferably for 24 hours a day. As one who was bewitched by a young wombat many years ago, and who has never recovered, I warn anyone who is thinking of undertaking the care of a wombat that they are committing themselves to many hours, night and day, for months to come, of looking after a fascinating and absorbing animal, of toiling constantly for a very appealing baby that is utterly dependent on them and yet is innately independent and selfsufficient – some might say stubborn. (See Plate 23.) Most road victim orphans are between four and eight months old; any younger, they are extremely difficult to rear, and most do not survive (Figure 8.1). Older ones are out of the pouch and usually flee into the bush when the mother is killed – only a few of these would survive.

The wandering wombat When it is about eight months old an orphan wombat, which would normally be leaving the pouch for gradually longer and longer periods, will begin to explore its new home more and more thoroughly, until there is not a corner of it that it does not know intimately. This intimacy, unfortunately, includes the use of corners, particularly dark ones under beds or inside cupboards or wardrobes, as toilets. Where, in the wild, the young wombat will seek the cover of undergrowth for this purpose, a housebound orphan will find the nearest equivalent. Usually it develops a 124

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0

1

2

3

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Figure 8.1 This young wombat was about 3.5 months old when it was orphaned. Animals orphaned as young as this are extremely difficult to rear, but many do survive if given the correct care. Photo: L Dovey

preference for only one or two suitable latrine areas – suitable to the wombat, that is. They may be less desirable to the owner of the wardrobe or the bed selected by the wombat as its substitute for a bracken clump. There are several other fundamental habits of the wombat that an orphan will find alternative means of performing when access to its normal environment is not possible. The legs of chairs and tables serve as replacements for roots and tree branches, which are habitually gnawed to keep the ever-growing teeth in trim, while wall corners and door jambs are ideal rubbing posts. Digging is one of the most essential and basic activities in a wombat’s life, and even a very young one will practise it. Loamy soil, of the kind found in garden beds, is ideal for a beginner, but it will soon need more challenging stuff. Unfortunately, the average suburban garden rarely contains large upturned trees, old rabbit warrens, steep gullies or other suitable burrow sites. Underneath the house itself is apparently the best available alternative, as many hand-reared wombats choose to dig their first burrow either under their own ‘family’s’ home or 125

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Figure 8.2 A sliding cupboard door is no barrier to a determined wombat.

under that of a neighbour. Even wombats reared on farms or in homes adjacent to bushland seem to prefer the foundations of a building as their first burrow site, and occasionally wild wombats also indulge in this regrettable activity. When a wombat, even a very young one, meets an obstruction, it either pushes through it or digs underneath it. In the house, a closed door comes into the category of an obstruction. Where a door will not yield to headbutting tactics, the adjacent floor will be subjected to intensive ‘digging’; while a wooden floor may not suffer very much from this onslaught, a carpet is never the same again. Still baulked, the wombat will usually attack the door itself; the scraping, scooping and biting actions used in excavating a burrow are all employed, often with remarkable success (Figure 8.2). This kind of determined attack on a door usually takes place because of another of the young wombat’s instincts: its fundamental need to follow and be near its mother at all times. So a young wombat left alone, either in the house or outdoors, will try to reach its human ‘parent’, and it is quick to learn that doors are the means of ingress or egress, even if they are closed. A young wombat also learns the law of cause and effect at an early age, and one instance of this is its use of a bite as a method of communication. 126

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When a wombat wants something – food, a romp, or just company – it will bite the nearest human leg. Finding that a nip on the ankle, even a gentle one, gains the human’s attention, it is a short step then for the orphan to obtain its particular requirement. Success leads to frequent use of this method of expression; and as the wombat grows, so does the strength of its bite. It also acquires an assortment of signals, in addition to the bite, that are as clear as any verbal language, provided that the human is receptive enough to interpret them. Another aspect of the wombat’s normal way of life that can cause some friction and difficulty in the home is its tendency to be active at night, rather than during the day. At first, when the orphan is small and being fed and attended to frequently, this nocturnal habit is not noticeable, but as it grows it begins to spend more of the daylight hours asleep, saving its energy for the evening and night. Lack of sleep is a chronic condition among wombat fosterers. ‘Things that go bump in the night’ are nothing in comparison to a wombat looking for entertainment.

Compromise All this may sound as though I am trying to discourage the practice of hand-rearing orphaned wombats, but this is not so. However, too many people attempt it unaware of what is entailed in raising a well-adjusted wombat. In most households, furniture-chewing and carpet-digging are unpopular pastimes, not to mention cupboard-exploring and doordemolishing, so compromises have to be made by both the human and the wombat. A wombat that has almost constant human company and frequent supervised rambles in a large garden, or, better, an area of bushland, will do little or no damage to the house at all – it has no reason to (Figure 8.3). Some people find the task of rearing a wombat beyond them, and so the orphan is passed to a zoo or a privately owned wildlife park. Others find it such a rewarding, entertaining and enjoyable experience that they tolerate the inconveniences and nurture the wombat until it is ready for independence.

The weaned wombat Usually a wombat will wean itself, sometimes suddenly, and by the time it is 14 or 15 months old it is normally getting all its nourishment from grasses. The need to dig, and the urge to wander and explore beyond the 127

Wombats

Figure 8.3 This orphan took the opportunity to have some digging practice during a supervised ramble in natural bushland.

confines of the house and garden, get stronger and stronger as it grows. No longer a cuddly bundle of complacency, the young wombat at 18 months is a hefty 15–20 kilogram package with a determination to get its own way that is awe-inspiring. The knotty problem arises: how and where do you return a hand-reared wombat to its natural environment? The decision to do so is usually made with a mixture of sadness and relief: sadness because the attachment that can, and nearly always does, form between the wombat and its human family is amazingly strong; relief because even the most devoted foster parent begins to think longingly of an uninterrupted night’s sleep by the time the wombat is about 18 months old.

Return to the wild The wombat’s chances of survival in the larger world will depend on several factors; the choice of an eventual release area should be balanced against these factors. To illustrate, here are three case histories of wombats reared in differing situations. Wombat A has been reared in an outer-suburban home. He is given access to the small neat garden and loves to romp with the family dog. He 128

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eats very little grass but dotes on muesli and dog chow, with biscuits and cake as titbits. His foster family fears for his safety, as his urge to roam threatens to overcome the doors and fences, and he is in imminent danger of becoming yet another road accident victim or a novel quarry for the neighbourhood dog pack. The children of the family are devoted to him, but the adults’ devotion is wearing as thin as the carpet. The edict has been issued: ‘That wombat must go!’ Wombat B’s foster home is a small mixed farm in a valley of small mixed farms from which wombats were eradicated many years ago. She is allowed to roam freely in and out of the house during the day and lives on the farm’s pasture grasses. She is locked up for the night in an old stable, but has dug her way out on several occasions and wandered as far as a neighbouring farm, where she has begun to dig a burrow under the house. The neighbour is complaining that his house is sagging and has threatened to shoot the wombat if she visits his farm again. Wombat C lives with a National Parks ranger and his wife. The doors of their home open on to natural bushland, and the orphan is one of a number of wombats that have been reared there. Some of these other wombats still visit the house, which has a ‘wombat door’ – an enlarged version of a ‘cat door’. The young wombat has spent many hours exploring the surrounding bush at his foster mother’s heels, eating a wide variety of forest grasses and practising his digging skills on an old burrow begun by an earlier orphan. Although he still sleeps in the house for part of the day, he is becoming very restless at night and will soon want to make unaccompanied expeditions into the bush. What are the alternatives facing the fosterers of these three young wombats, and what are the chances of survival? The first option that occurs to many people is to send the young wombat to a zoo where they believe it will be safe and well cared for. This is true, but it will also be living a very restricted and unnatural life. A wombat is essentially an independent creature, and a life of close confinement must be almost intolerable until the animal’s senses are dulled by the endless boredom. Privately owned wildlife parks are a newly flourishing industry, and some of these parks have permits to accept young hand-reared wombats. Here they will have a limited amount of freedom as well as continuing contact with humans. This might be the best solution for an orphan such as wombat A, which has had no opportunity to adjust to its natural environment, with all its risks and uncertainties. 129

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The ultimate aim is, of course, to return the wombat to the wild, but achieving this is not as simple as it sounds. People who drive out into the country, take the wombat out of the car and, while it is investigating its novel surroundings, drive away without it, are not only very stupid but also cruel in the extreme. The wombat is unlikely to live long enough to ‘return to the wild’. If its distress and confusion, as well as its physical miseries of hunger and exposure, do not lead to its death, then a dog or a motor vehicle almost inevitably will. Releasing a hand-reared wombat in the bush can have a reasonable chance of a successful outcome only if considerable time and effort are spent over the venture. If the site for release is carefully chosen, and if a familiar human can stay at the site with the wombat while it gradually settles into its new environment, there is a fair chance that it will survive. A camping or caravanning holiday spent in an area of wombat habitat will enable an 18-month-old orphan to taste the delights of being a wild wombat while remaining in contact with its human family and will make the eventual separation less distressing for both. With this kind of introduction to the wild, wombat A might eventually become habituated to ‘living free’, provided that he did not meet a dog out hunting for a meal before his familiarity with the family pet was forgotten. Wombat B would almost certainly adapt successfully. Wombat C, of course, has excellent prospects of being assimilated into the local bush scene while still retaining the security of his foster home. His foster parents might still suffer from disturbed nights, but they would have the compensation of continuing to enjoy contact with the orphan (Figure 8.4). I began this chapter by quoting a ‘wombat owner’. I will end it by contradicting myself: no-one ever ‘owns’ a wombat. Nor do wombats make good pets. Although an orphan wombat is utterly dependent on a human for its food and comfort, it never becomes truly domesticated; it remains a wild animal, content for a time to share a home with people.

Postscript: a word of warning It is ironic that the unique and lovable wombat, which can so easily become attached to humans, also has humans as its worst enemy. Since all three species are now protected in all states, there is probably less direct and indiscriminate killing, but land-clearing for agriculture continues to fragment the southern hairy-nosed wombat’s limited range, and while the 130

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Figure 8.4 And so – farewell!

northern hairy-nosed wombat is now safe from humans this protection has come almost too late for that species. The wildlife laws do not stop the bulldozers from pushing higher and higher up the slopes of the Great Dividing Range or into the Tasmanian wilderness, the last bastions of the bare-nosed wombat. It is not necessary to kill the wombats directly; the destruction of their habitat will exterminate them more quickly than guns, traps or poison. The bare-nosed wombat is not an endangered species. It is not even rare, but we would do well to remember that even the most abundant species can quickly become rare or extinct if its habitat is destroyed. It is up to us to ensure that it never becomes the Uncommon wombat.

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APPENDIX 1: GROWTH AND DEVELOPMENT Approximate age

Weight range

At birth

0.5 g

Hairless; mouth, front limbs and shoulders well developed; eyes and most other organs embryonic; sharp curved claws on front feet but hind limbs undeveloped; lips joined at outer edges.

1 month

5g

Permanently attached to teat; ears still fused with the skin of the head; hind legs developing; outer edges of lips still joined together; still hairless.

3 months

100–110 g

Facial structures forming; ears fully unfolded but lying close to head; whiskers forming but otherwise still hairless; lips still joined.

3.5 months

230–250 g

Fine fur forming on ears; eyes may be open; still permanently attached to teat.

4 months

380–400 g

Eyes open; lips beginning to separate.

5 months

750–800 g

Fine layer of fur on dorsal side of limbs; no longer permanently attached to teat; lips fully separated; lower incisors erupting.

6 months

1–1.4 kg

Fine fur about one millimetre long over much of the body; skin of nose and soles of feet still pink; first molars visible, upper incisors erupting; head out of pouch occasionally.

7 months

2.2–2.5 kg

Fur thicker; premolars and second molars erupt; ventures out of pouch when in burrow.

8 months

2.7–3.4 kg

Fully furred but rudimentary tail still visible; muzzle still narrow and ears appear too large for head; out of pouch more often; nibbling grass while in pouch with head out, as well as when out beside mother.

9 months

3.6–5.2 kg

10 months

5–6.4 kg

Leaves pouch permanently; soles of feet darkening, also skin of nose; suckles from elongated teat; stays close to mother most of the time; eats more and more grass; probably eats mother’s scats occasionally to establish bacterial colonies in its digestive system.

12 months

7.3–11.3 kg

State of development

15 months

12–19 kg

Weaned during this period; remains with mother for a variable time after weaning.

18 months

16.8–24 kg

Usually independent.

Data for this table were obtained from measurements of bare-nosed wombats taken on 42 road kills, 17 hand-reared wombats, and from data given in Presidente (1982) and McIlroy (1973). Data compiled by Taggart et al. (2007) for the southern hairy-nosed wombat is very similar to the above. The study of northern Tasmanian bare-nosed wombats by Green and Rainbird (1987) gives more detailed descriptions of growth and development.

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APPENDIX 2: HAND-REARING ORPHAN WOMBATS

Some Dos and Don’ts DO contact your local wildlife authority to obtain permission to keep the orphan. (Reason: Wombats are protected wildlife and can be kept only if this permission is granted. Officers of the authority can take the orphan from you at any time if you do not have this permission, or if you do not give the orphan adequate care.) DO, once you have obtained permission to keep the orphan, make contact with one of the organisations with experience in the care of orphan marsupials. To find the one nearest to you, check ‘Animal Welfare Organisations’ in the Yellow Pages of your local telephone directory. DON’T attempt to rear an orphan wombat unless you are prepared to give up a great deal of your personal freedom in order to care for it properly. (Reason: Caring for all marsupial young requires a great deal of care, hard work and patience. Unfurred young are similar to premature human babies in that they need even more care than furred young.) DO provide a warm pouch and some form of heat source, preferably a heatpad. A hot water bottle can be used in an emergency, but it must be frequently renewed. Try to keep the pouch at a temperature of about 36°C (about 96–98°F), the same as human body temperature. (Reason: Pouch young cannot control their own body temperature, but rely on their mother’s 35–39°C body heat.) DO line the pouch with soft sheeting or similar material. If the wombat is unfurred, gently rub the skin with a lubricant once a day. Pawpaw cream is recommended, but if it is unavailable pure lanolin can be used sparingly.

134

Appendix 2

(Reason: The mother’s pouch is lined with soft, moist skin; the atmosphere in the pouch is humid. An orphan can become dehydrated by evaporation of water from the skin. Oily lubricants should not be used; they prevent the skin from respiring and they harbour bacteria. Lubricants containing chemicals can irritate the skin.) DO keep a newly orphaned wombat quiet and undisturbed by young children, dogs, etc. Cuddle it as often as possible. Carrying the young wombat around, either in your arms or better still in its pouch, slung around your neck and shoulder, is sometimes the only way to calm a newly orphaned animal. (Reason: Stress and shock can cause death. Nearness to a substitute mother can minimise stress.) DON’T feed the wombat on cow’s milk in any form, fresh or tinned or powdered, but … DO use a low-lactose milk such as Di-Vetalac, available from veterinarians. There are also two marsupial milk replacers which offer three stages of wombat milk – use the one formulated for the developmental stage of the orphan. These replacers are Biolac, PO Box 93, Bonnyrigg NSW 2177, phone (02) 9823 9874, and Wombaroo Food Products, PO Box 151, Glen Osmond SA 5064, phone (08) 8391 1713. (Reason: Marsupial milk has a much higher protein and fat content than cow’s milk, but is very low in lactose. Pouch young cannot digest lactose; severe diarrhoea often results from feeding milk rich in lactose, and death from dehydration may then result.) DO weigh the wombat in order to estimate its age (see Growth and Development Table) and as a guide to how much milk it should take per day. (Reason: It is recommended that an orphan marsupial take approximately 10–15% of its body weight in millilitres of liquid daily. For example, a 750 gram wombat (about five months old) needs 75–112 millilitres of liquid per day; at two kilograms it needs 200–300 millilitres per day.)

135

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DO feed ‘little and often’ – every two hours for unfurred young, every 3–4 hours for furred young. After a time the orphan will probably want to be fed ‘on demand’. This is ideal if it can be done. (Reason: In the pouch the young has access to the teat at all times, and it can take just as much as it needs when it needs it.) DO store milk mixture in the refrigerator, but keep it for no longer than 24 hours, and … DO clean all feeding utensils after each use. Regular sterilisation by boiling or the use of chemicals such as Milton is recommended, and … DO gently wipe away any milk that is left on the wombat’s chin or around its mouth after feeding. (Reason: Careful hygiene is necessary to prevent bacterial and fungal infections, some of which can be fatal if untreated.) DON’T add Pentavite or other vitamin drops to the diet. (Reason: Wombats do not need much vitamin D, and they get their other vitamin requirements from the low-lactose milk and, later, from grass. Severe kidney damage, caused by hypervitaminosis, has been found in hand-reared wombats that have been fed supplementary vitamins. Diarrhoea can also be caused by excessive use of vitamins.) DON’T use a calf teat or baby teat. Special marsupial teats are available from some veterinarians and can also be obtained from Biolac and Wombaroo Food Products. (Reason: The young wombat’s mouth is very small and narrow and can be damaged by a large teat.) DON’T force feed, but … DO persevere gently. A newly orphaned animal will often refuse food for days, but even a few drops at a time, given frequently, will keep it alive until it settles down and begins to suck properly. Nurse the young in your arms, allowing it to lie on its back while feeding. (Reason: If force fed, milk can pass into the lungs, causing aspiration pneumonia, usually resulting in death. In the pouch 136

Appendix 2

the young wombat lies on its back to suckle from the teat on the inner pouch wall.) DO gently wipe the young wombat’s cloaca after meals. It will often produce urine and/or faeces at that time, but don’t worry if it does not. Some orphans will themselves turn about in the pouch so that the rear section protrudes and will then urinate or defecate – very good if you can catch it! I have found that some orphans will eliminate their wastes if ‘held out’ like a baby. (Reason: The wombat’s pouch points towards the rear, so it is very difficult for the mother to clean the young in the pouch in the way that kangaroos do. Pouch young in the wild have been seen to push their rear section out of the pouch for urinating and defecating.) DO provide an older orphan with a ‘toilet area’ such as a dark cupboard lined with newspaper. (Reason: In the wild a young at-heel wombat always seeks cover, such as bracken clumps, when it defecates. In the house an orphan will use dark corners such as under beds, as toilets, if a suitable place is not provided and its use encouraged.) DO reduce the concentration of the milk substitute by about 50% if diarrhoea develops, but … DON’T reduce the amount of liquid given. Increase it if possible, by giving additional fluid such as boiled water, especially if the diarrhoea is severe. Do not allow diarrhoea to go untreated; seek veterinary advice. (Reason: Death from dehydration can occur if too much fluid is lost from the bowels.) DO allow the young wombat access to grass when it is about eight months old. Muesli, rolled oats, grated or chopped carrot, etc. can also be offered at this time, but its chief food is still the milk substitute. Bread, cake or sweet biscuits should not be given except occasionally or in very small amounts. (Reason: Grasses, and milk while it is young, are the wombat’s only natural foods. Processed carbohydrates can cause diarrhoea.) 137

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DON’T feed it dry hay or grass with sharp stems. (Reason: These can cause impactions and can also perforate the intestine and cause a slow and painful death.) DO at the same time as grass is made available, also allow it access to soil and, if possible, to the fresh scats (droppings) of another wombat. (Reason: Bacteria in the wombat’s colon are necessary for the digestion of grass etc. These digestive bacteria, sometimes called ‘stomach flora’, can sometimes be obtained by the wombat from soil or from the faeces of other wombats.) DO watch out for diarrhoea when the young begins to eat grass, and at weaning time. Give half a teaspoon of natural yoghurt once a day, in the milk substitute, or, for larger young, two-thirds of a teaspoon of yoghurt and one-third of cottage cheese. (Reason: Yoghurt will help to introduce micro-organisms into the digestive system. Only natural yoghurt or acidophilus tablets should be used.) DO allow the wombat to be with you and to follow you about the house and garden. Play with the orphan and allow it to explore the garden and, if possible, take it for walks in natural bushland. It will stay at your heels until it gains confidence, and will gradually learn how to cope with life in the bush. DON’T be surprised if the young wombat eats its own scats. (Reason: It is only trying to increase the bacterial content in its colon.) DO provide branches with bark on them for the young wombat to gnaw. (Reason: The wombat’s teeth grow constantly, and it must gnaw to keep them in trim. Table and chair legs may not suffer so much if an alternative is provided.)

From about 10 months of age onwards DO give the young wombat opportunities to dig in the ground. (Reason: Digging, for a wombat, is as natural as breathing.) 138

Appendix 2

DON’T cut the wombat’s claws. (Reason: They are naturally very long when it is young, but gradually become blunted with digging.) DO if possible, at this age or earlier, rear the wombat with another of about the same age. If this cannot be arranged, gradually start to wean the wombat from human company. (Reason: If it becomes less dependent on humans it is better able to adapt when it is eventually ready for release.) DO continue to provide milk substitute as well as grass. Weaning usually occurs at about 15 months of age. DO seek veterinarian advice if the orphan shows any sign of sickness or disease. Mange is a common problem, but in many cases it can be cured by following a strict regime of care. The Wombat Protection Society has an excellent web page which gives information on the treatment of mange. (www.wombatprotection.org.au) DO remember that the prime objective is to return the orphan to the wild as soon as it is able to fend for itself. The gauge of success is that the wombat is able to adjust easily to life in the wild and that it will be able to breed successfully.

If you live in an area where the wombat can move safely from your home to the bush DO try to keep the wombat safely enclosed at night until it is about 18 months old. DO go with it as often as possible to explore the bush. DO be prepared to give the wombat its freedom when it is 18 months to two years old.

If you do not live near bushland DO try to take the wombat to its natural environment as often as possible. 139

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(Reason: If the wombat has no opportunities to adapt to life in the wild, it will probably die if it is suddenly released there. Many orphan wombats have to be sent to zoos and wildlife parks because they have not had a chance to adapt to the wild.)

140

REFERENCES AND FURTHER READING

Chapter 1 Archer M (1984). Evolution of arid Australia and its consequences for vertebrates. In Vertebrate Zoogeography and Evolution in Australasia. (Eds M Archer and G Clayton) pp. 97–108. Hesperian Press, Carlisle, WA. Archer M (1984). Effects of humans on the Australian vertebrate fauna. In Vertebrate Zoogeography and Evolution in Australasia. (Eds M Archer and G Clayton) pp. 151–61. Hesperian Press, Carlisle, WA. Archer M (1984). The Australian marsupial radiation. In Vertebrate Zoogeography and Evolution in Australasia. (Eds M Archer and G Clayton) pp. 661–6. Hesperian Press, Carlisle, WA. Archer M (1984). The status of Australian dasyurids, thylacinids and myrmecobiids. In Vertebrate Zoogeography and Evolution in Australasia. (Eds M Archer and G Clayton) pp. 1015–21. Hesperian Press, Carlisle, WA. Archer M and Clayton G (Eds) (1984). Vertebrate Zoogeography and Evolution in Australasia. Hesperian Press, Carlisle, WA. Archer M, Clayton G and Hand S (1984). A checklist of Australian fossil mammals. In Vertebrate Zoogeography and Evolution in Australasia. (Eds M Archer and G Clayton) p. 1041. Hesperian Press, Carlisle, WA. Archer M and Hand S (1984). Background to the search for Australia’s oldest mammals. In Vertebrate Zoogeography and Evolution in Australasia. (Eds M Archer and G Clayton) pp. 517–66. Hesperian Press, Carlisle, WA. Bewick T (1811). History of Quadrupeds. 6th edn. Reprinted 1970. Ward Lock, London. Calaby J (1984). Changing the face of a continent. In Vertebrate Zoogeography and Evolution in Australasia. (Eds M Archer and G Clayton) pp. 1011–14. Hesperian Press, Carlisle, WA. Cooke BD (1998). Did introduced European rabbits Oryctolagus cuniculus (L.) displace common wombats Vombatus ursinus (Shaw) from part of their range of South Australia? In Wombats. (Eds RT Wells and PA Pridmore) pp. 262–70. Surrey Beatty and Sons, Chipping Norton. Flannery T (1984). Kangaroos: 15 million years of Australian bounders. In Vertebrate Zoogeography and Evolution in Australasia. (Eds M Archer and G Clayton) pp. 817–36. Hesperian Press, Carlisle, WA. 141

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Green RH and Rainbird JL (1987). The common wombat Vombatus ursinus (Shaw, 1800) in northern Tasmania – Part 1. Breeding, growth and development. Records of the Queen Victoria Museum No. 91. Green RH and Rainbird JL (1988). The common wombat Vombatus ursinus (Shaw, 1800) in northern Tasmania – Part 2. The Bass Strait population. Records of the Queen Victoria Museum No. 92. Hornadge B (1972). ‘If it moves shoot it …’ Review Publications, Dubbo. Mallett KJ and Cooke BD (1986). The Ecology of the Common Wombat in South Australia. Nature Conservation Society of South Australia, Adelaide. Marshall AJ (1966). The Great Extermination. Heinemann, Melbourne. Murray PF (1998). Palaeontology and palaeobiology of wombats. In Wombats. (Eds RT Wells and PA Pridmore) pp. 1–33. Surrey Beatty and Sons, Chipping Norton. Quirk S and Archer M (1983). Prehistoric Animals of Australia. Australian Museum, Sydney. Rich T (1984). Australia’s largest marsupial, Diprotodon: its ancestry, palaeobiology and extinction. In Vertebrate Zoogeography and Evolution in Australasia. (Eds M Archer and G Clayton) pp. 995–7. Hesperian Press, Carlisle, WA. Stephenson NG (1967). Phylogenetic trends and speciation among wombats. Australian Journal of Zoology 15, 873–80. Tyndale-Biscoe H (2005). Life of Marsupials. CSIRO Publishing, Melbourne. Van Dyck S and Strahan R (Eds) (2008). The Mammals of Australia. 3rd Edn. Reed New Holland, Sydney. Wünschmann A (1970). Die Plumpbeutler (Vombatidae). A Ziemsen Verlag, Wittenberg Lutherstadt.

Chapter 2 Dawson TJ (1983). Monotremes and Marsupials: The Other Mammals. Edward Arnold, London. Green RH (1973). The Mammals of Tasmania. The author, Launceston. Green RH and Rainbird JL (1987). The common wombat Vombatus ursinus (Shaw, 1800) in northern Tasmania – Part 1. Breeding, growth and development. Records of the Queen Victoria Museum No. 91. Green RH and Rainbird JL (1988). The common wombat Vombatus ursinus (Shaw, 1800) in northern Tasmania – Part 2. The Bass Strait population. Records of the Queen Victoria Museum No. 92. Jones FW (1923). The Mammals of South Australia. Part II. The bandicoots and herbivorous marsupials. Government Printer, Adelaide. 142

References and further reading

Tyndale-Biscoe H (2005). Life of Marsupials. CSIRO Publishing, Melbourne. Young GE (1980). Geographic variation in the common wombat, Vombatus ursinus (Shaw, 1800). Victorian Naturalist 92, 200–4.

Chapter 3 Finlayson HH (1961) Mitchell’s wombat in South Australia. Transactions of the Royal Society of South Australia 85, 207–15. Horsup AB and Davidson C (1994). Recovery Plan for the Northern Hairynosed Wombat, Lasiorhinus krefftii. 2nd edn. Report to Australian Nature Conservation Agency. Johnson CN and Crossman DC (1991). Dispersal and social organisation of the northern hairy-nosed wombat, Lasiorhinus krefftii. Journal of Zoology London 225, 605–13. McIlroy JC (1973). Aspects of the ecology of the common wombat, Vombatus ursinus (Shaw, 1800). PhD thesis. Australian National University, Canberra. McIlroy JC, Cooper RJ and Gifford EJ (1981). Inside the burrow of the common wombat, Vombatus ursinus (Shaw, 1800). Victorian Naturalist 98, 60–3. Nicholson PJ (1963) Wombats. Timbertop Magazine 8, 32–8. Shimmin GA, Skinner J and Baudinette RV (2002). The burrow architecture and environment of the southern hairy-nosed wombat (Lasiorhinus latifrons). Journal of Zoology, London 258, 469–77. Steele VR and Temple-Smith PD (1998). Physical structure of warrens of a small colony of southern hairy-nosed wombats Lasiorhinus latifrons. In Wombats. (Eds RT Wells and PA Pridmore) pp. 113–24. Surrey Beatty and Sons, Chipping Norton. Troughton E (1941). Furred Animals of Australia. Angus and Robertson, Sydney.

Chapter 4 Brown GD (1964) Thermoregulation in the common wombat (Vombatus ursinus) in an alpine environment. In Thermal Physiology. (Ed JRS Hales) pp. 331–34. Raven Press, New York. Brown G and Young G (1962). Wombats – amiable native lawnmowers. Australian Natural History 20, 279–83. McIlroy JC (1973). Aspects of the ecology of the common wombat, Vombatus ursinus (Shaw, 1800). PhD thesis. Australian National University, Canberra. 143

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Nicholson PJ (1963). Wombats. Timbertop Magazine 8, 32–8. Wells RT (1978). Thermoregulation and activity rhythms in the hairy-nosed wombat Lasiorhinus latifrons (Owen), (Vombatidae). Australian Journal of Zoology 26, 639–51. Wells RT (1989). Vombatidae. In Fauna of Australia. Mammalia. Vol. 1B. (Eds DW Walton and BJ Richardson) pp. 755–68. Australian Government Publishing Service, Canberra. Wünschmann A (1970). Die Plumpbeutler (Vombatidae). A Ziemsen Verlag, Wittenberg Lutherstadt.

Chapter 5 Barrett C (1927). Wombats and their ways. Australian Natural History 3, 66–71. Brown GD and Taylor LS (1984). Radiotelemetry transmitters for use in studies of the thermoregulation of unrestrained common wombats, Vombatus ursinus. Australian Wildlife Research 11, 289–98. Burbidge NT (1984). Australian Grasses. Australian Natural History Library, Angus and Robertson, Sydney. Burt WH (1943). Territoriality and home range concepts as applied to mammals. Journal of Mammalogy 24, 346–52. Chauncy N (1950). The story of Rastus – a wild wombat. Wildlife, Melbourne 12, 395–7, 423, 465–7, 476. Clifford HT and Watson L (1977). Identifying Grasses. University of Queensland Press, Brisbane. Evans MC, Macgregor C and Jarman P (2006). Diet and feeding selectivity of common wombats. Wildlife Research 33 (4), 3231–330. Ewer R (1968). Ethology of Mammals. Logos Press, London. Finlayson GR, Shimmin GA, Temple-Smith PD, Handasyde KA and Taggart DA (2005). Burrow use and ranging behaviour of the southern hairy-nosed wombat (Lasiorhinus latifrons) in the Murraylands, South Australia. Journal of Zoology 265, 189–200. Gaughwin MD (1979). The occurrence of flehmen in a marsupial – the hairy nosed wombat (Lasiorhinus latifrons). Animal Behaviour 27, 1063–5. Green RH and Rainbird JL (1987). The common wombat Vombatus ursinus (Shaw, 1800) in northern Tasmania – Part 1. Breeding, growth and development. Records of the Queen Victoria Museum No. 91.

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References and further reading

Green K (2005). Winter home range and foraging of common wombats Vombatus ursinus in patchily burnt subalpine areas of the Snowy Mountains, Australia. Wildlife Research 32(6), 525–9. Horsup AB and Davidson C (1994). Recovery Plan for the Northern Hairynosed Wombat, Lasiorhinus krefftii. 2nd edn. Report to Australian Nature Conservation Agency. Jewell PA (1966). The concept of home range in mammals. Symposium of the Zoological Society of London 18, 85–109. Johnson CN and Crossman DC (1991). Dispersal and social organisation of the northern hairy-nosed wombat, Lasiorhinus krefftii. Journal of Zoology London 225, 605–13. Leuthold W (1977). African Ungulates: A Comparative Review of Their Ethology and Behavioural Ecology. Vol. 8. Springer Verlag, Berlin. Leyhausen P (1964). The communal organisation of solitary mammals. Symposium of the Zoological Society of London 14, 249–63. Mallett KJ and Cooke BD (1986). The Ecology of the Common Wombat in South Australia. Nature Conservation Society of South Australia, Adelaide. Marks CA (1984). The effects of seasonal variation in ambient temperature on the activity rhythms of the common wombat, Vombatus ursinus (Shaw, 1800). Project report, Victoria College, Rusden. McIlroy JC (1973). Aspects of the ecology of the common wombat, Vombatus ursinus (Shaw, 1800). PhD thesis. Australian National University, Canberra. McIlroy JC (1976). Aspects of the ecology of the common wombat, Vombatus ursinus. Capture, handling, marking and radio-tracking techniques. Australian Wildlife Research 3, 105–16. Meredith C (1984). Observations of native mammals wintering above the snowline in the Victorian Alps. Victorian Naturalist 101, 95–6. Ralls K (1971). Mammalian scent marking. Science 171, 443–9. Stoddard DM (1976). Mammalian Odours and Pheromones. Edward Arnold, London. Taylor RJ (1993). Observations on the behaviour and ecology of the common wombat Vombatus ursinus in northeast Tasmania. Australian Mammalogy 16 (1), 1–7. Wakefield NA (1967). A Naturalist’s Diary. Longman, Melbourne. Wells RT (1978). Thermoregulation and activity rhythms in the hairy-nosed wombat, Lasiorhinus latifrons (Owen), (Vombatidae). Australian Journal of Zoology 26, 639–51.

145

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Willis JE (1972). A Handbook to Plants in Victoria. Vol. 1: Ferns, Conifers and Monocotyledons. Melbourne University Press, Melbourne.

Chapter 6 Banks SC, Skerrat LF and Taylor AC (2002). Female dispersal and relatedness structure in common wombats Vombatus ursinus. Journal of Zoology 256, 389–99. Barboza PS, Hume ID, Beal AM and Dawson TJ (1985). Digestion and digesta passage in the common wombat (Vombatus ursinus). Abstract. Australian Mammal Society Bulletin 9, 49. Barboza PS and Hume ID (1992). Digestive tract morphology and digestion in the wombats (Marsupialia: Vombatidae). Journal of Comparative Physiology B 162, 552–60. Brown G and Young G (1982). Wombats – amiable native lawnmowers. Australian Natural History 20, 279–83. Conder P (1970). Breeding of common wombat in captivity. Victorian Naturalist 87, 322. CSIRO Film Unit (1965). Birth of the Red Kangaroo. CSIRO, Melbourne. Gowland PN (1973). Aspects of the digestive physiology of the common wombat Vombatus ursinus (Shaw, 1800). Honours Zoology thesis. Australian National University, Canberra. Green RH and Rainbird JL (1987). The common wombat Vombatus ursinus (Shaw, 1800) in northern Tasmania – Part 1. Breeding, growth and development. Records of the Queen Victoria Museum No. 91. Green RH and Rainbird JL (1988). The common wombat Vombatus ursinus (Shaw, 1800) in northern Tasmania – Part 2. The Bass Strait population. Records of the Queen Victoria Museum No. 92. Horsup AB and Davidson C (1994). Recovery Plan for the Northern Hairynosed Wombat, Lasiorhinus krefftii. 2nd edn. Report to Australian Nature Conservation Agency. Hume ID (1982). The digestive physiology of marsupials. Comparative Biochemistry and Physiology 71A, 1–10. Hume ID (1982). Digestive Physiology and Nutrition of Marsupials. Cambridge University Press, Cambridge. Marks CA (1989). An observation of courtship and mating in the free-ranging common wombat (Vombatus ursinus). In Wombats. (Eds RT Wells and PA Pridmore) pp. 125–8. Surrey Beatty and Sons, Chipping Norton.

146

References and further reading

Minchin AK (1937). Notes on the weaning of a young koala (Phascolarctos cinereus). Records of the South Australian Museum 6, 1–3. Molina K and Sanson G (1982). Molar morphology and occlusion in Vombatus ursinus. Abstract. Australian Mammal Society Bulletin 7 (2), 34. Peters OG and Rose RW (1979). The oestrous cycle and basal body temperature in the common wombat (Vombatus ursinus). Journal of Reproduction and Fertility 57, 453–60. Peterson RT (1966). The Mammals of Eastern Canada. Oxford University Press, Toronto. Presidente PJA (1982). Common wombat Vombatus ursinus; maintenance in captivity, blood values, infectious and parasitic diseases. In The Management of Australian Mammals in Captivity. (Ed. DD Evans) pp. 133–43. Zoological Board of Victoria, Melbourne. Taggart DA, Finlayson GR, Shimmin G, Gover C, Dibben R, White CR, Steele V and Temple-Smith PD (2007). Growth and development of the southern hairy-nosed wombat, Lasiorhinus latifrons (Vombatidae). Australian Journal of Zoology 55 (5), 309–16. Taylor AC, Alpers D and Sherwin WB (1998). Remote censusing of northern hairy-nosed wombats Lasiorhinus latifrons via genetic typing of hairs collected in the field. In Wombats. (Eds RT Wells and PA Pridmore) pp. 156–64. Surrey Beatty and Sons, Chipping Norton. Taylor RJ (1993). Observations on the behaviour and ecology of the common wombat Vombatus ursinus in northeast Tasmania. Australian Mammalogy 16 (1), 1–7. Tyndale-Biscoe H (2005). Life of Marsupials. CSIRO Publishing, Melbourne. Waser PM and Jones WT (1983). Natal philopatry among solitary mammals. Quarterly Review of Biology 58, 355–90. Wünschmann A (1970). Die Plumpbeutler (Vombatidae). A Ziemsen Verlag, Wittenberg Lutherstadt.

Chapter 7 Borchard P, McIlroy J and McArthur C (2008). Links between riparian characteristics and the abundance of common wombat (Vombatus ursinus) burrows in an agricultural landscape. Wildlife Research 35, 760–7. Breckwoldt R (1983). Wildlife in the Home Paddock. Angus and Robertson, Sydney.

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Chesterfield EA, Macfarlane MA, Allen D, Hutchinson MN, Triggs BE and Barley R (1983). Fauna and Flora of the Rodger River Forest Block, East Gippsland, Victoria. Ecological Report 1, Forests Commission of Victoria, Melbourne. Calaby JH (1969). Australian mammals since 1770. Australian Natural History 16, 271–5. Doube LJ (1981). Wildlife diseases of the Pacific Basin and other countries. Proceedings of the 4th International Conference of the Wildlife Disease Association. pp. 63–75. University of California, Davis, California. Ealey EMH (1969). The wombat. Victorian Naturalist 86, 64–6. Gaughwin MG, Judson GJ, the late Macfarlane WV and Siebert BD (1984). Effect of drought on the health of wild hairy-nosed wombats, Lasiorhinus latifrons. Australian Wildlife Research 11, 455–63. Hornsby PE (1982). Predation of the euro Macropus robustus (Marsupialia: Macropodidae) by the European fox Vulpes vulpes (Placentalia: Canidae). Australian Mammalogy 5, 225–7. Horrocks GFB, Opie AM, Carr GW, Cherry KA, Brown GW, Craig SA and Triggs BE (1984). Flora and Fauna Survey of the Ellery Forest Block, East Gippsland, Victoria. Ecological Report 3, Department of Conservation, Forests and Lands, Melbourne. Lawrence GE (1966). Ecology of vertebrate animals in relation to chaparral fire in the Sierra Nevada foothills. Ecology 47, 278–91. Marks CA (1998). Review of the humaneness of destruction techniques used on the common wombat Vombatus ursinus in Victoria: In Wombats. (Eds RT Wells and PA Pridmore) pp. 287–97. Surrey Beatty and Sons, Chipping Norton. Marks CA (1998). Field assessment of electric fencing to reduce fence damage by the common wombat Vombatus ursinus. In Wombats. (Eds RT Wells and PA Pridmore) pp. 298–304. Surrey Beatty and Sons, Chipping Norton. McIlroy JC (1973) Aspects of the ecology of the common wombat, Vombatus ursinus (Shaw, 1800). PhD thesis. Australian National University, Canberra. McIlroy JC (1982) The sensitivity of Australian animals to 1080 poison. III Marsupial and eutherian herbivores. Australian Wildlife Research 9, 487–503. McIlroy JC and Rishworth C (1998). The effect on common wombat Vombatus ursinus populations of replacing native eucalypt forests with plantations of Monterey Pine Pinus radiata. In Wombats. (Eds RT Wells and PA Pridmore) pp. 271–9. Surrey Beatty and Sons, Chipping Norton. 148

References and further reading

Mech LD (1970). The Wolf: The Ecology and Behaviour of an Endangered Species. Natural History Press, New York. Munday BL (1976). Marsupial disease. Proceedings No. 36 for Course for Veterinarians. University of Sydney, Sydney, pp. 335–85. Neal E (1955). Badgers in Woodlands. Forestry Commission Forest Record Leaflet 34, Her Majesty’s Stationery Office, London. Newsome AE, McIlroy JC and Catling PC (1975). The effects of an extensive wildfire on populations of twenty ground vertebrates in south-east Australia. Proceedings of the Ecological Society of Australia 9, 107–23. Newsome AE, Corbett LK, Catling PC and Burt RJ (1983). Feeding ecology of the dingo I. Stomach contents from trapping in south-eastern Australia, and the non-target wildlife also caught in dingo traps. Australian Wildlife Research 10, 477–86. Newsome AE (1983). The feeding ecology of the dingo II. Dietary and numerical relationships with fluctuating prey populations in southeastern Australia. Australian Journal of Ecology 8, 345–66. Nicholson PJ (1963). Wombats. Timbertop Magazine 8, 32–8. Opie AM, Cherry KA, Horrocks GFB, Carr GW, Schulz M and Triggs BE (1984). Flora and Fauna Survey of the Yalmy Forest Block, East Gippsland, Victoria. Ecological Report 2, Department of Conservation, Forests and Lands, Melbourne. Pearse RJ (1972). Should the wombat be protected in New South Wales? Parks and Wildlife 1, 61–3. Presidente PJA (1982). Common wombat Vombatus ursinus; maintenance in captivity, blood values, infectious and parasitic diseases. In Management of Australian Mammals in Captivity. (Ed. DD Evans) pp. 133–43. Zoological Board of Victoria, Melbourne. Rishworth C (1990). The effect of the conversion of native forest to plantations of Pinus radiata on the common wombat, Vombatus ursinus (Shaw, 1800). Honours thesis. Australian National University, Canberra. Rolls EC (1969). They All Ran Wild. Angus and Robertson, Sydney. Skerratt LF (1998). Diseases and parasites of the common wombat Vombatus ursinus from the Healesville area of Victoria. In Wombats. (Eds RT Wells and PA Pridmore) pp. 317–28. Surrey Beatty and Sons, Chipping Norton. Skerratt LF (2004). The effects of sarcoptic mange on the behaviour of wild common wombats (Vombatus ursinus). Australian Journal of Zoology 52 (3), 331–9. St John BJ and Saunders GM (1989). Plan of management for the hairynosed wombat (Lasiorhinus latifrons) in South Australia. Report published 149

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by the South Australian Parks and Wildlife Service, Department of Environment and Planning, South Australia. St John BJ (1998). Management of southern hairy-nosed wombats Lasiorhinus latifrons in South Australia. In Wombats. (Eds RT Wells and PA Pridmore) pp. 228–42. Surrey Beatty and Sons, Chipping Norton. Taylor AC, Alpers D and Sherwin WB (1998). Remote censusing of northern hairy-nosed wombats Lasiorhinus latifrons via genetic typing of hairs collected in the field. In Wombats. (Eds RT Wells and PA Pridmore) pp. 156–64. Surrey Beatty and Sons, Chipping Norton. Tenby ID (1998). The law and wombats in Australia. In Wombats. (Eds RT Wells and PA Pridmore) pp. 305–11. Surrey Beatty and Sons, Chipping Norton. Triggs BE, Brunner H and Cullen JM (1984). The food of the fox, dog and cat in the Croajingalong National Park, south-eastern Victoria. Australian Wildlife Research 11, 491–9. Tyndale-Biscoe H (2005). Life of Marsupials. CSIRO Publishing, Melbourne. Wildlife Act (1975). Victorian Government Gazette 84, 2740. Wünschmann A (1970). Die Plumpbeutler (Vombatidae). A Ziemsen Verlag, Wittenberg Lutherstadt.

Chapter 8 Carter J (1972). Wild Animal Farm. Rigby, Adelaide. Finnie EP (1976). Husbandry and diseases of orphaned pouch-young marsupials. Australian Veterinary Practice March, 19–28. Fleay R (1957). Growing up with wombats. Animal Kingdom 60, 107–10. Hand S (Ed.) (1990). Care and Handling of Australian Native Animals. Surrey Beatty and Sons, Sydney. Walraven E (1990). Taronga Zoo’s Guide to the Care of Urban Wildlife. Allen & Unwin, Sydney.

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INDEX

Page numbers in bold refer to illustrations or photographs Aborigines 4, 5, 117 activity above ground 41–67 in burrow 36–40 seasonal 40 aggression 58–63 albinism 14 ancestry 1–4 bacteria causing infection 99, 120, 133, 135 in digestive tract 76, 83 bare-nosed wombat breeding season 85, 89 description 13, 14, 17, 92–3 food 49, 49–50, 51, 53–4, 54, 96 home range 56–8 social behaviour 58–60, 59 bear 8, 9 bedding material 25 behaviour aggressive 60–4 defensive 6, 15, 59, 76, 77, 116–7 feeding 49–54, 58, 59, 75, 93, 96 grooming 43–6, 43–7 maternal 74–80, 80 play 74, 78, 79, 97 reproductive 64–5, 85–9, 88 social 58–60 birth 9, 69–70, 133 body temperature 39–40, 70, 86, 134 bounty 103–4 breeding season 85, 86, 89 burrow cleaning 34 conditions in 24–5, 32, 34, 40, 100, 102 destruction of 102, 113, 115 entrance 22, 23, 24–6, 27, 28–30, 36, 39, 42, 67 excavation of 28, 31–4, 33, 79, 95, 125–6, 128 length 22, 25–6, 29, 30 research 21–2, 29–30, 39, 40 sites 26–8, 27, 30, 57, 94, 105, 111, 125–6 tunnels 21, 24–6, 29–30, 34, 54, 102 use of 28–9, 34, 54–5, 58, 84, 119 bushfires 34, 53, 101, 101–3, 116

151

caecum 76, 82, 83 cardio-gastric gland 10, 81, 82, 82 cat 44, 120 claws description 14, 18, 19 injuries to 99, 107 in young 70, 75, 79, 133, 139 use in digging 22, 32, 33 use in feeding 51 use in grooming 45 cloaca 64, 66, 69, 74, 137 coat colour 14, 15, 92, 93 texture 14, 15 colon 76, 82, 82–3, 138 conflict with humans 8–9, 103–16 conservation 104, 128 control 103–11 copulation 86, 87, 88 courtship 64, 87, 88 defence 15, 56, 76, 77, 116–7 development 70–5 diarrhoea 135, 136 diastema 17, 18, 81 diet 49–54, 81, 124, 136 digestion 76, 81–3, 82 digging 28, 31–4, 33, 79, 95, 108, 110, 125–6, 128 dingo control 112, 113 cross-breeding 117 fence 106, 117 history of 5–6, 117, 119 predation by 15, 34, 41, 77, 99, 101, 105, 117 Diprotodon 2, 4 Diprotodonta 9, 10, 17, 19, 83 discovery 6, 7, 8 disease 98, 100, 118–121 dispersal 84, 121 distribution before European settlement 6 fossil 2, 3 present 11, 12 DNA 84, 118 dog in burrows 15, 34 control 113 cross-breeding 117

Wombats

diseases 119, 120 history 6, 118, 119 predation by 41, 77, 99, 101, 116–7, 128, 129 dominance 60 drinking 56, 56 drought 50, 52, 53, 57, 58, 86, 100–1, 105, 106 dust-bathing 48–9, 57

growth

ear 16, 45, 62, 62, 70, 71, 75, 84, 89, 133 emergence from burrows 40, 41–2, 43, 54, 103 erosion 111, 113, 121 evolution 1–4 eye 14, 16, 36, 42, 47, 70, 71, 106, 119, 133

Ice Age 2, 4, 6 ileum 82, 82 injuries 62, 99, 117 insects 39, 83, 120

face 14, 15, 16, 17, 90 faeces 22, 58, 64, 74, 76, 83, 120, 137, 138, see also scats feeding areas 49, 56, 57 behaviour 49–54, 49, 51, 53, 59–60, 59, 93, 96 feet 2, 18–9, 19, 25, 38, 39, 55, 61, 70, 72, 73, 79, 95, 97, 133 fence damage 107, 105, 108 dingo 106 electric 109–10 fighting 60–1, 99 flehmen 64–5 flooding 24, 28, 32, 33, 100 food mastication 81 plants eaten 49–54 fossil record 1–4 fox in burrows 34 history 118, 119 predation by 77, 116–7 fumigation 107 fur colour 14, 15, 92, 93 development in young 71, 72, 74, 85, 97, 132 texture 14, 15

kangaroo birth 70, 89 bushfires 102 digestion 83 ears 16 feet 19 grooming 74, 137 history 1, 2, 4, 5, 6, 9 poisoning 112 teeth 81 koala 1, 9–10, 10

70–2, 84, 89, 90, 132–3

habitat 4–5, 5, 11, 41, 53, 59, 101, 106, 113, 117, 130, 131 hand-rearing 98, 123–7, 134–40 hearing 17 home range 56–8, 59, 60, 61, 63, 66, 85, 115 hunting 4, 5, 103–4

jaw

9, 17, 18, 18, 50, 56, 81, 117

lactation 19, 71, 74, 89 Lasiorhinus 4 krefftii see northern hairy-nosed wombat latifrons see southern hairy-nosed wombat legal protection 104, 106, 130–1 lips 17, 71, 79, 81, 97, 132 longevity 90 mange 42, 98, 100, 118–9, 139 mastication 81 mating 86–9, 88, 98 milk 71, 76, 79, 81, 86, 124, 135–6 mites 118–9 mortality 101, 103–7, 112–3, 115–6, 116, 124 mound 22, 23, 24, 32, 42, 65 northern hairy-nosed wombat burrows 29–31, 94 description 14, 15, 91 food 50 home range 58 social behaviour 60 vocalisations 60

gait 55 gestation 29, 69, 89 grasses digestion of 81, 127, 137 eaten by wombats 49–52, 101, 108, 116, 129 growth 40, 57, 86, 102, 103, 114, 115 grooming 44–7, 44–7

oestrus cycle

152

60, 85, 86

Index

olfaction 17, 63–6 orphan 98, 123–31, 125, 126, 128, 134–40 ovulation 45, 86

chambers 24, 25, 26, 34, 36, 39, 40 postures 37, 37, 38, 39 small intestine 82, 82, 83, 120 snakes 34 social behavior 58–60, 59, 12 southern hairy-nosed wombat breeding season 85–6 burrows 29–31, 30, 94 description 14, 15, 17, 91 food 50, 52 home range 58 social behaviour 60 vocalisations 60 sperm 10 stomach 10, 39, 81, 82, 82, 83, 138 swamp wallaby 54, 117 swimming 56

parasites external 39, 118–20 internal 120 paths 30, 55, 57 penis 19 Phascolomys medius 2 Phascolonus gigas 2, 3, 4 pheromones 63–6 pig 9, 109, 118, 120 play 74, 78, 79, 86, 98 Pleistocene 2, 4, 6 poisoning 103, 106–7, 111–3, 115, 131 population control 121 possum 1, 5, 8, 19, 34, 61, 83, 112 pouch cleaning 45, 69, 70, 74 conditions in 19–20, 70, 73–4 emergence from 69, 74, 75 opening 20, 45, 69, 70, 72, 74, 75 young 19, 29, 70–4, 73, 97, 123, 132, 134–7 predators 6, 34, 104, 116–8

tail 9, 14, 38, 39, 44, 46 taxonomy 9–10 teat 19, 70, 71, 72, 74, 76, 97, 132, 136, 137 teeth eruption 72, 74 function 51, 81 growth 17–8 incisor 18, 72 molar 17, 18, 18, 72, 74 pre-molar 18, 74 territory 58, 60 testes 19 thylacine 6, 117 ticks 39, 118, 119–20 toes 9, 18, 19, 45, 70 trapping 103–4, 106, 107, 112, 113, 115, 131 travelling 43, 54, 55, 57, 80, 98, 99, 103 tunnels 21, 24–6, 29–30, 34, 54, 102

rabbits burrows 28, 34 control 106, 107, 109, 111–2, 115 damage by 12, 108, 121 history 118 radio-tracking 22, 57, 58, 69 Ramsayia lemleyi 2 Ramsayia magna 2 reproduction 9, 64, 85–9 respiration rate 39 Rhizophascolonus crowcroftii 2 road kills 115–6, 116, 123, 130 rubbing posts 36, 36, 44, 44, 48, 57, 58, 125

urine 64, 65, 74, 117, 137 uterus 9

scats 23, 25, 46–8, 48, 50, 63, 64, 65–6, 76, 77, 83, 85, 108, 117, 118, 132, 138 scent glands 63, 64, 66 marking 63–4, 66 trails 36, 66 scrotum 19, 46 sexual characteristics 19–20 sight 16, 63 sit 22–3 size 13–4 skin 15, 17, 19, 20, 38, 39, 44, 70, 71, 118–9, 132, 134 skull 9, 15, 16, 18, 34, 118 sleeping

vocalisations 60, 61, 62, 76, 77 Vombatus hacketti 4 Vombatus ursinus see bare-nosed wombat Warendja wakefieldi 2 weaning 76, 79–81, 85–6, 89, 127, 133 weight 13–4, 15, 19, 70, 71, 74, 75, 77, 84, 89, 112, 132-3, 135 whiskers 16, 71, 97, 132 wildlife authority 123, 134 park 127 wombat gate 109, 110, 111 zoo 127

153