The Red Kangaroo in Central Australia: An Early Account by A. E. Newsome 148630155X, 9781486301553

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The Red Kangaroo in Central Australia An Early Account by A. E. Newsome

Thomas Newsome and Alan Newsome

The Red Kangaroo in Central Australia An Early Account by A. E. Newsome

Thomas Newsome and Alan Newsome

This book is dedicated to Alan Newsome (1935–2007).

The Red Kangaroo in Central Australia An Early Account by A. E. Newsome

Thomas Newsome and Alan Newsome

© Thomas M Newsome 2016 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 Newsome, Alan Eric, author. The red kangaroo in central Australia: an early account by A. E. Newsome / Thomas Newsome and Alan Newsome. 9781486301553 (paperback) 9781486301560 (epdf) 9781486301577 (epub) Includes bibliographical references and index. Red kangaroo – Australia, Central. Kangaroos – Australia, Central. Aboriginal Australians – Australia, Central. Australia, Central – Social life and customs. Newsome, Thomas, author. 599.2223 Published by CSIRO Publishing Locked Bag 10 Clayton South VIC 3169 Australia Telephone: +61 3 9545 8400 Email: [email protected] Website: www.publish.csiro.au Front cover: red kangaroo (photo: Samantha Hopley)

Edited by Anne Findlay, Editing Works Pty Ltd Cover design by Andrew Weatherill Typeset by Thomson Digital Index by Bruce Gillespie Printed in China by 1010 Printing International Ltd 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. The copyright owner shall not be liable for technical or other errors or omissions contained herein. The reader/user accepts all risks and responsibility for losses, damages, costs and other consequences resulting directly or indirectly from using this information. Aboriginal and Torres Strait Islander readers are warned that photographs in this book may contain images of deceased persons which may cause sadness or distress. Original print edition: The paper this book is printed on is in accordance with the rules of the Forest Stewardship Council®. The FSC® promotes environmentally responsible, socially beneficial and economically viable management of the world’s forests.

Foreword

At 22 Alan Newsome’s task was to learn all he could about red kangaroos in Central Australia for the cattle industry. Tim Ealey was doing the same in the Pilbara, Harry Frith in western New South Wales and Tom Kirkpatrick in southern Queensland. The approach of all of them was to shoot samples of kangaroos at regular intervals and record all that was possible about their age, reproduction and health. Alan also used light aircraft to estimate the abundance and distribution of the kangaroos across the land, a technique that has since been widely adopted by others. On 16 trips between October 1959 and October 1962 Alan shot 2000 red kangaroos on the plains north of the MacDonnell Ranges in Central Australia. The data collected from these animals were published in 12 scientific papers between 1964 and 1980, which provided the first, and still the most comprehensive, study of the ecology of this quintessential Australian animal. By one of those quirks of fortune that smile on some scientists, Alan’s study began in the longest drought

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experienced in Central Australia since European arrival and ended as the drought broke in 1962. He witnessed the massive decline of the cattle from their pre-drought peak of 300 000 to less than a third of that number by the end of the study. In that process of decline the impact of stock grazing on the native mammals was made plain to him. The smaller species were disappearing and the red kangaroos were responding in their reproduction to the extreme conditions. He discovered the phenomenon of drought-induced anoestrus in this species and, after the drought broke, he witnessed the extraordinarily rapid response of females to breaking rains, ovulating within 10 days and long before any new shoots appeared. And he discovered that drought also affected the associated males; many had no sperm and reduced testosteronesecreting cells. As they recovered more slowly after breaking rains, many of the females that ovulated failed to become pregnant. Because of this, recruitment into red kangaroo populations is very uneven, with large numbers in good years and none in other years: in Alan’s study the major recruitment to the population had occurred 12 years before in the exceptionally good years of 1947–1949. He then examined the rainfall records for the previous century looking for similar exceptionally good years and found 17 favourable periods of longer than one year, from which he concluded that recruitment to the population is probably always episodic. A similar pattern has since been shown for rock wallabies in Queensland and may be a common adaptation to the uncertain climate by other species of animals and plants of arid Australia.

Foreword

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These were all big discoveries in a field that was just beginning, but what was special about Alan Newsome’s study was his personal interaction with the Aranda men who were his helpers; they taught him Dreamtime songs and stories about their ancestral being, Ara, the red kangaroo that were grounded in a deep understanding of its adaptations to the land and the uncertainties of the climate; what impressed Alan was that 10 of the 14 totemic sites in the overland journey of Ara were places that he had independently identified as drought refuges to which the kangaroos retreated during the drought years of his study. These were stream lines and grassy plains near the main ranges, where new green shoots grew and trees gave shelter. The underground journey of Ara was more difficult to understand because it traversed the desert, which his informants said was never occupied by Ara. Alan interpreted the story to mean that no one knew how Ara could travel to the distant totemic site except by a magical underground route. And the reason that Ara could not travel across that country was because it was devoid of watering places and trees to provide shelter in hot weather. The first cattle brought into Central Australia after 1870 were likewise restricted to the flood plains and unable to graze out on the Mitchell grass plains until 1938, when bores were sunk to provide water for stock. This provided water for kangaroos as well, but more importantly, grazing by cattle stimulated the plants to put out green shoots. It enabled the red kangaroos to extend their range greatly and had led to large recruitment of kangaroos in the 1950s. But it also

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took them away from shade on the treeless plains with sub-fertility the consequence. What is strange is that none of us who were Alan’s colleagues and read his papers at the time knew anything about his wonderful encounter with the Aranda and the congruence of their knowledge and his until he published it 20 years later in the anthropological journal Mankind. It is now evident that Alan had wanted to share his formative experiences as a young biologist discovering the wisdom and knowledge of the first people of the land and had written much of it, but then it languished as other responsibilities took precedence. It is so rare for a practising scientist to write about the experience of discovery and how it is done, more especially in such a hard environment as Central Australia, so it is especially fortunate that Alan’s unfinished manuscript was discovered by his son, Thomas. Despite its unfinished state it invites comparison with the classics of Australian natural history such as Francis Ratcliffe’s Flying Fox and Drifting Sand, Harry Frith’s The Mallee Fowl, the bird that makes an incubator and Eric Rolls’ They All Ran Wild. Hugh Tyndale-Biscoe

Colour plates

Plate 1: Red kangaroo in Central Australia (c. 1960s).

Plate 2: Aboriginal from Haast’s Bluff throwing a spear (August 1958).

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Plate 3: Aboriginals from Haast’s Bluff with red kangaroo (August 1958).

Plate 4: The Burt Plain, with Limestone Bore and Mt Hay in the background (June 1978).

Colour plates

Plate 5: Extensive mulga (green bands) north of the MacDonnell Ranges (November 1967).

Plate 6: Satellite image of Burt Plain ( c. 1970).

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Plate 7: Swarms of budgerigars at Delmore Downs (December 1967).

Plate 8: Mitchell grass on clay soils adjacent to ranges on the Burt Plain (June 1974).

Colour plates

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Plate 9: Gilgai showing mature plants of the perennial grass neverfail, which, after grazing by cattle, provide green growth for red kangaroos to eat during drought. Nardoo colonises the deeper parts of the gilgai (c. 1970).

Plate 10: Wild flowers on show after rains in Central Australia (c. 1970).

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Plate 11: Mulga woodlands on the Burt Plain ( c. 1970).

Plate 12: Spinifex grassland in Central Australia (c. 1970).

Colour plates

Plate 13: Aerial surveying. A lone red kangaroo can be seen from the aircraft ( c. 1960s).

Plate 14: Red kangaroos in the shade ( c. 1970).

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Plate 15: Example of a red kangaroo resting site, or hip-hole ( c. 1970).

Plate 16: Inspecting the pouch young of a red kangaroo ( c. 1970).

Contents

Foreword Colour plates Preface Acknowledgements

Chapter 1

Introduction

Chapter 2

Landforms, climate and vegetation

Chapter 3 Chapter 4

v ix xix xxvii

1 15

Landforms

16

Climate

19

Vegetation

27

Distribution and abundance

33

Reproduction

47

Field studies

49

The effects of drought on female reproduction

53

Female reproduction – entering anoestrus

56

Female reproduction – breeding after rain

58

Male reproduction

58

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Chapter 5

Chapter 6

Chapter 7

Food and water

67

Food

69

Water

78

Sociology

87

Group size

88

Ecomythology

105

Footnotes/glossary

127

References

131

Index

139

Preface

I first discovered a draft version of this book in 2010. It was buried beneath the piles of material that Alan Newsome, my father, left in our Canberra home. There was no title, just a folder labelled ‘Red Kangaroo Book’. Some chapters were typed; others were in Alan’s customary scrawl. From the various letters I found, it appears that Collins Publishers (now HarperCollins) was previously interested in publishing this book. The correspondence showed that a synopsis was agreed upon and a draft manuscript was expected by 1975. Professor H.G. Andrewartha (a prominent ecologist acting as an adviser for Collins Publishers) commented on several draft chapters and he met with Alan to discuss the book on several occasions. In the correspondence I have found from Collins Publishers to Alan, the publisher appeared optimistic, with Stephen Dearnley stating that ‘the book could be readable and interesting for an intelligent amateur naturalist with an inquiring mind’. Why the book was never published is unclear. I suspect that time constraints delayed further progress at Alan’s end.

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The same letter from Stephen Dearnley suggests that he thought the project simply required some single-minded attention on Alan’s part in order for it to be completed: ‘I feel it would help now if you could concentrate your time to spend it on the book so that the thread of the story would remain active in your mind and make it much easier to keep an even style and flow. Do you think you would be in a position to settle down fairly solidly on it now?’ That statement, dated 17 July 1975, appears in the latest correspondence I have been able to locate. Finding this correspondence some 30 years later I found myself pondering the same questions I imagine any person who encounters the unpublished work of a giant in their field confronts: was this book worthy of completing given it was first drafted so many years ago? Would anyone actually read it? How would Alan feel if it was published given he evidently put it to one side for years even before his early death? What has convinced me to complete this work for publication is the belief that this work represents something unique in the history of field ecology in Australia. It is rare for an ecologist to write reflectively and personally about the experience of discovery, especially during the early stages of a career. Perhaps that is in part a result of the emphasis nowadays placed on the need for young scientists to have strong publication records in peer-reviewed journals, though I suspect it is also because few early career scientists have a journey that results in the kind of pioneering discoveries that Alan’s did. His early years spent exploring Central Australia

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were no less remarkable for what emerged from his exploits as they were for his age when he undertook that research. He did, after all, arrive in Central Australia in 1957, age 22 and fresh from completing an undergraduate science degree at The University of Queensland. In his first year, while working as a field biologist for the Animal Industry Branch of the Northern Territory Government, he travelled extensively between Alice Springs and Darwin accruing thousands of kilometres on the odometer (see next page). For the next 15 years he traipsed through the arid zone documenting what he found, attempting to comprehend the remarkable ecology of the various species he encountered, and in the first instance, that of the red kangaroo. I hit my strides as an ecologist during the period when Alan was suffering from the effects of dementia caused by Alzheimer’s disease. He was still able to draw my attention to his favourite papers, most of which came from his time in Central Australia, but I did not work with him as a colleague. My only experiences working with him come from my childhood when I went out with him on various field trips. At that time I was too young to appreciate the significance of Alan and his colleagues’ work for the development of ecological knowledge in Australia. On a personal note then, the discovery of Alan’s manuscript has given me the chance to read, in Alan’s own words, the stories from this ‘era of discovery’ that he could not tell me himself. I have no doubt that it was because of Alan and his influence on my childhood that Central Australia was a

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AREA COVERED BY FIELD BIOLOGIST 1958–59

DARWIN

NEWCASTLE WATERS

TENNANT CREEK

ALICE SPRINGS

Area covered by A.E. Newsome 1958–59. (Source: Ken Johnson).

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The researcher and his vehicle.

place I sought out to visit in my early twenties. In 2005 I moved to Alice Springs to work as an environmental consultant. The Tanami Desert subsequently became the field site for my doctoral studies on the ecology of the dingo. Through my various travels throughout Central Australia I visited many of the places where Alan conducted his studies on the red kangaroo. I often wondered what the country would have looked like during that earlier period. Alan had arrived there on the cusp of its transformation: in 1957, when he arrived, many species were literally disappearing from the landscape. It was part of the devastating extinction wave that is still progressing today.

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During Alan’s early years in Central Australia he had the seemingly impossible task of working out why some species were going extinct, while others appeared to be flourishing. He had little published scientific literature to rely upon. His knowledge came from observations and from intensive field studies conducted under extreme conditions. He drew insights from the journals of European explorers and early collecting trips by Hedley Finlayson. Most importantly though, Alan drew knowledge from and worked closely with the Indigenous occupants of the land. He was one of the first to understand the possibilities of enriching Western science with Indigenous knowledge, particularly with respect to the red kangaroo. The last chapter provides Alan’s article, ‘The EcoMythology of the Red Kangaroo in Central Australia’, published in 1980 in Mankind 12(4), 327–333, which has been reproduced with kind permission from Wiley. The paper was one of those that he frequently referred to as his favourite, even in his last years. It was, however, one of his hardest to get published and it remains one of his least cited papers. For those who knew Alan its inclusion will not come as a surprise, though for others I hope the publication of this manuscript gives some context as to why Alan saw that paper as so important to his work as an ecologist. It remains a groundbreaking piece of work, a pioneering example of why ecologists and land managers alike should listen to, and learn from, Indigenous knowledge. I should conclude with some observations about the editing process I have undertaken in order to prepare this work for publication. I felt it best to retain Alan’s voice.

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Thus I have kept the first person style in which Alan wrote it, and the substantive text remains his voice, not mine. Because some of the chapters were incomplete, I have taken the liberty of deleting parts of the original text or editing and adding text in places to maintain clarity for the reader. There were no tables in the original text. The ones which now appear come either from Alan’s publications or from the vast array of other unpublished materials and musings he left in our garage. Similarly, the manuscript I found in the garage did not include any photos. I have included in this edited version copies of photos taken or collected by Alan during his time in Central Australia, many of which my mother and I found in the boxes of slides Alan also left behind. I have created and inserted maps in the hope that they provide context for readers less familiar with the study species and geography of Central Australia. Finally, in some instances I have amended the references where I could not locate the original source material. I have also used the endnotes as a place to include, for the benefit of the reader, commentary on terminology or historical facts that may be relevant. While the process of deciding to prepare this manuscript for publication, and then editing it to this final form, was a deeply personal one, my hope is that its publication inspires and informs the further development of ecological research and knowledge in Australia. That, after all, was Alan’s passion and remained his life’s work long after he put to one side his early draft of this work on the red kangaroo in 1975. Thomas Newsome

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Alan Newsome in Central Australia in the 1960s.

Acknowledgements

The initial encouragement to publish this book came from Chris Dickman and Libby Robin. Chris also provided many helpful edits and comments. Those edits and comments, and the many other ways Chris has supported my research, greatly contributed to the final version of this book and the opportunity to finish it. Once underway, this project was improved by the generous contributions of many others. Discussions with my father’s great friend Dick MacMillen in the USA in 2014 taught me many more things about my father and this part of his research. Hugh Tyndale-Biscoe was equally generous. He met in person to discuss, in particular, the chapter on red kangaroo reproduction. Hugh wrote the Foreword, and I am grateful for his edits and contribution, and for providing his perspectives on Alan’s red kangaroo research. Ken Johnson kindly provided the map of Alan Newsome’s travels in 1958–59. Bill Low also offered his thoughts on the book when I first found it in 2010. At that time, I was living in Alice Springs and much of what I have learned about the flora

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and fauna of Central Australia was taught to me by Bill. Without such knowledge, I would have found it enormously difficult to interpret the works of my father. More recent field trips in the Simpson Desert with my colleagues at The University of Sydney provided a captive audience and many helpful suggestions. Special thanks to Emma Spencer and Eveline Rijksen for reading each chapter. Thanks also to my mother, Jane Thompson and my wife, Fiona Roughley. Mum helped me read my father’s handwriting, sorted through boxes of his slides to find the best pictures to include for publication, proofed the manuscript, and has encouraged this project and my research the whole way through. Fiona proofed the manuscript and was my first point of contact for grammatical questions. Finally, it is fitting that this book is being published by CSIRO Publishing. After all, Alan Newsome had a long career with CSIRO and I am grateful that CSIRO Publishing continues to publish works of ecological, historical and scientific significance. Thomas Newsome

1 Introduction

Not all that long ago in geological time, giant marsupials roamed the forests, plains and swamps of Australia. All are now extinct. One group, the diprotodontids, were particularly huge, much larger than any modern marsupial. Nototherium was the size of a cow, and Diprotodon and Zygomaturus, that of a rhinoceros. The latter had a massive metre-long skull. There were, also, giant kangaroos, Macropus (the forerunner of modern kangaroos), Sthenurus, and Procoptodon, which stood about 3 m tall! Preying upon these grazers and browsers was another giant, Thylacoleo carnifex, the marsupial lion.1 About 100 000 years ago, these great creatures began to die out. The reasons are unknown. Giant mammals of all kinds in all continents died out similarly.

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Gross changes in world climate are usually invoked as the cause. Some of the giant marsupials survived until ~30 000 years ago, e.g. the kangaroos, Macropus ferragus and Sthenurus. Since Aborigines arrived at least 40 000 years ago, it has been suggested that they hunted them to extinction, or else, through their use of fire to flush game or provide easy traverse, grossly changed ancestral habitats (Jones 1968; Merrilees 1968). Thus, it is argued, forests were razed, vast grasslands formed and the forest dwellers of the time were denied their livelihood.2 Today, in drier times, the survivors of those marsupial giants are the modern kangaroos. Five species, the euros (Osphranter) and giant kangaroos have come down to about one-third to one-quarter the size of their ancestors, but the sixth, the red kangaroo (Megaleia3) (Plate 1), is unchanged. It appeared in the late Pleistocene (over 12 000 years ago), after the others, and is perhaps the most modern form of kangaroo. All kangaroos and wallabies are, however, closely related to one another. In captivity, some will even interbreed, though the hybrids are all sterile (Calaby & Poole 1971). In any part of Australia today, one species of kangaroo or another can be found, adapted to wet temperate forests, arid plains or the monsoonal tropics. Only one species is truly restricted to the arid inland, the red kangaroo (Fig. 1.1). That so large an animal should thrive in so capricious an environment is remarkable because it is dependent on green grass for food, even in drought. Australia is a droughty land. The great size of the arid hinterland makes it one of the driest continents on Earth.

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Figure 1.1: Distribution of the red kangaroo in Australia.

Flat, waterless, lightly timbered plains commence abruptly inside the eastern highlands and stretch almost unrelieved for ~3000 km to the western coast, encompassing ~5 000 000 km2 in all. The whole of Europe could be neatly packaged inside it. This is the range of the red kangaroo. For almost 100 years after the First Fleet landed in Australia in 1788, the environment of Central Australia defied exploration by the European colonists. The experiences of white explorers are proof of the harshness and aridity of the environment. Captain Charles Sturt,4 a British explorer, was forced back by the

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terrible heat and desolation of Sturt’s Stony Desert. Robert O’Hara Burke and William John Wills,5 through folly and hard luck, perished on Cooper’s Creek, a little further inland. The impetuous Ludwig Leichhardt,6 a Prussian explorer and naturalist, disappeared without trace to this day, probably in the Simpson Desert or even further inland.7 Ernst Giles,8 that hardy romantic, lost his horses and his offsider Alfred Gibson off to the west in the desert Giles named after him, to survive himself, only by superhuman endeavour. He walked back across the desert ~150 km to base camp in stupefying heat, driven almost mad by thirst and hunger. Only John McDouall Stuart9 triumphed. This doughty Scot, much praised by Sturt for thoroughness as a surveyor on the expedition mentioned above, crossed Australia from south to north right through the driest parts, and did not lose a man. He succeeded by finding water, establishing camp there, and then setting off to find more. If he found it, the expedition moved on. If he failed to do so, he retreated to the base camp to replenish his water bags and take another course. In this way he slowly picked his way across the land. Twice he was turned back to Adelaide by hardships. There he remained a scant few months to regroup and rest, and then was off again. Stuart succeeded in his third attempt. We now know that through his thoroughness, determination and bushmanship, Stuart found the only possible corridor through that forbidding country – a great feat, but the ordeal cost him his health. It comes as a surprise, then, to learn that this hot, dry and desolate land, explored by European men at such cost,

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5

was inhabited by thriving Aboriginal tribes. Indeed, throughout Central Australia, McDouall Stuart traversed a densely populated region inhabited by the largest and most powerful tribe of inland Australia, the Aranda people. To them, it was not a desolate land. About them were familiar plants and animals, astonishing really for so arid a region. The fauna in these areas, for example, ranges from earthworms, snails, fish and frogs, to hardy reptiles, birds and mammals. Many creatures survive by clinging to the only permanent moisture, the few rock holes in the ranges and rivers. Others burrow or are strictly nocturnal to avoid the heat. A few are drought hardy. But how can such large animals like the red kangaroo survive there? Indeed, how did the Aboriginal peoples do so? The key to the success of the Aboriginals was behavioural. They knew their country so well, its waterholes both temporary and permanent and places to find food, that life, sometimes a rich one, was possible. They conquered the land with their wits. As mentioned previously, however, the red kangaroo had one special ecological requirement – green grass to eat. Of all things in an arid land this can be rare stuff. The red kangaroo lives mainly where there are lightly timbered and grassy plains; it is rare in the true open deserts. Of all Australian marsupials, it is the one whose ecology is best understood.10 Though the red kangaroo has been studied at eight widespread localities throughout its range, this book concentrates largely on Central Australia (Fig. 1.2). There are several reasons for this. Above all, it is the country that I know best. Luckily, also, my five-year

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Figure 1.2: The region of focus in this book. Labels are provided for key townships, study locations and landscape features.

study there extended through good seasons and bad. The simple environment, and sharp climatic shifts, induced clear-cut changes in the kangaroos’ lifestyle. But there is one other great advantage. European settlement in Central Australia was closer to its origins and to the primordial environment in the Centre than elsewhere in inland Australia. Some of the grazing pioneers are still alive, and provided accounts of red kangaroos (and other fauna) in the early days. Several of them arrived to mine gold at Arltunga or Tanami, others to graze sheep and cattle. Some, not all that long ago, had described their experiences to chroniclers about the penetration of white man to their tribal lands. And some, born before that penetration, had not long since died. As a boy, old ‘Sloper’, a Warramunga, saw his tribesmen turn McDouall Stuart back at Attack Creek on 25 June 1860.

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He died at Tennant Creek in 1956 about 103 years old. The recollections of these European graziers and Aboriginal tribesmen helped answer such questions as these: were kangaroos abundant then or not; what was the environment like, especially the vegetation, before white man released domestic stock upon the land? After all, there were still Aboriginals who clung to their tribal lives and beliefs; so much could be learnt from them during my time in Central Australia. When I first went to Central Australia in 1957, red kangaroos were abundant. Mobs of 50 and 100 were commonly seen on the open plains. Larger mobs were rare. The largest, seen just 15 km south of Alice Springs, was ~1500 strong.11 As I approached, it seemed that the entire plain got up and moved away. In the late 1950s, kangaroos were a hot political topic. They were regarded as pests depriving cattle and sheep of food. They were accused of eating out the pastures or fouling those they did not, so that stock would not eat them. According to news reports, red kangaroos were highly abundant, occurring ‘in millions’ throughout the Northern Territory, even in the ‘Top End’, as the country above Newcastle Waters is called. Collecting trips throughout the Northern Territory soon showed that the kangaroo referred to in the Top End was not the red kangaroo but the antilopine kangaroo (Osphranter antilopinus) (Fig. 1.3). This kangaroo has slender lines and similar colouring to the red kangaroo, as well as its habit of living on the flat country, so the mistake was readily understandable. Grey kangaroos (Macropus giganteus) were also incorrectly reported.

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Figure 1.3: Distribution of the euro and antilopine kangaroo in Australia.

In the Centre, what had been reported as grey kangaroos were in fact female red kangaroos, the ‘blue fliers’, whose fur is often smoky grey. Grey kangaroos do not live in the Centre; they live along the east and south coasts of Australia, ranging inland to the edge of semi-arid country. So the red kangaroo’s characteristic of being strictly a dry country animal was upheld. Indeed, it is one of only two kangaroos found in the truly arid country. The other is the euro (Osphranter robustus) that lives in the hills and ranges of inland Australia. Its distribution extends to the mountains of the Great Dividing Range in the east where it is blackish in colour, and is called the wallaroo (Fig. 1.3).

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There is little risk of confusing the two kangaroos of Central Australia. The euro sticks to the mountain ranges and valleys, has a long hairy coat of a brownish colour and is stockily built with a sturdy powerful gait. The red kangaroo lives on the surrounding plains, has a slender build, a short soft fur, and an easy graceful gait. Any doubt can be resolved by the characteristic white and black patches on either side of the muzzle of red kangaroos. There are other distinguishing features on the head. The naked nose of the euro is larger and more dog-like than that of the red kangaroo, the cheek bone (zygoma) is much broader in the euro and the foramen magnum (the hole at the base of the skull where the spinal cord emerges) is distinctly smaller. Other differences can be seen by comparing the nasal chamber and the upper incisors (teeth) (Fig. 1.4). Thus, the issue of incorrect identification and distribution of the red kangaroo was simply solved. But there still remained the problem of pastoral fouling and grazing by red kangaroos, and there still existed a plethora of biological questions to answer. For example, why were red kangaroos so abundant on open plains and creeks during droughts, and more so on some than others? Where did they disappear to after rain? Why were they so rare in the deserts at all times? Why did they sometimes congregate to form large mobs? What did they eat and did they compete severely or at all with cattle and sheep? How did kangaroos foul pastures as claimed? Did the movement of large mobs indicate migrations? How could five to 10 kangaroo shooters work one 500 km2 plain 50 km north of Alice Springs night after night in

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Figure 1.4: Examples of differences in the anatomy of red kangaroo and euro. Adapted from Wood Jones (1924) .

the 1950s without making an impression on numbers? Their breeding would seem to be prodigious for such to happen. So what were the reproductive processes, and what ensured reproductive success? There were further unanswered questions. Why did kangaroos appear to be more numerous on cattle country than land never stocked? Was it due to the stock waters man had made? If so, why were kangaroos so rarely seen at water? Had kangaroos always been so numerous? If so, why was there no mention of them in McDouall Stuart’s journals? Why had he to shoot a horse to stave off death

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11

from starvation in October 1862 near Mt Hay, in the heart of red kangaroo country, when a shot aimed blindly across the plains at night a century later could not have failed to fell one? Intensive studies of the kangaroo’s biology and ecology began to answer these questions in the late 1950s. Life-history studies began on captive animals in Adelaide (Sharman & Pilton 1964). And my own field studies began in Central Australia (Newsome 1964a,b, 1965a,b,c, 1966a,b, 1971a,b, 1973, 1975, 1977, 1980; Newsome et al. 1967). For my studies, red kangaroos were regularly surveyed for data on distribution and abundance (Chapter 3), reproduction (Chapter 4), diet (Chapter 5), and survival and longevity (Chapter 6). I later investigated the links between the findings of my own studies and Aboriginal mythology (Chapter 7). Throughout these studies I surveyed red kangaroos in stocked and unstocked country. I frequently visited the Aboriginal Reserve at Haast’s Bluff in the western MacDonnell Ranges (Fig. 1.2). The vegetation there was similar to that on the study-area further east, and on one occasion I camped with a group of ~50 Aboriginals on a waterhole halfway between Haast’s Bluff and Mt Liebig. This was my first acquaintance with these people. As a biologist, I was amazed and fascinated by their skills and knowledge, and by their memory of the country and its animals and plants. One day, they took me hunting. We went to a patch of mulga (Acacia aneura) ~15 km off, where fresh kangaroo tracks had recently been seen. Picking up more tracks, they began the hunt. The men dispersed into a shallow

12

The Red Kangaroo in Central Australia

dish-shaped formation in the trees. Those on the wings watched for the kangaroos, and the man at the base kept to the fresh tracks. They communicated mostly by signs but sometimes vocally, but so softly that I barely detected it. Having a rifle, I was regarded as the principal actor, but I was completely bewildered. Only the tracker and one other man could be seen in the thick scrub. And everyone but the important white man with the rifle knew what was going on. Obviously, the kangaroo was close by. The Aboriginals’ manner indicated that it was a sitting shot not more than 50 m off. But do you think I could see it? Not a hope. My clumsy attempts to locate the beast frightened it off. Much disgusted the men gave me up and went off after it with their spears and woomeras prudently fetched along (Plate 2). Shortly a great shout went up, and the hunters returned very pleased with the kangaroo, a large buck (Plate 3). Two days later, they took me hunting again. This time to an open plain close to Mt Liebig ~50 km off. There were a dozen or so kangaroos feeding out on the plain. I shot an ‘old man’ roo first, the largest there, then two others nearby. What I could not manage close up was accomplished simply at a distance. An old Aboriginal acting as a guide set about gutting the carcases. A slit about 10 cm long was made in the stomach wall of each kangaroo with a small white flake of quartz taken from his hair. Out of these slits, he pulled the viscera, including the food-filled paunch. To keep out the flies, he then closed the slits with small twigs pushed

1: I n t r o d u c t i o n

13

through the skin on either side, twisting it round and round. The viscera lay on the ground. The old man had two small children in his charge. It was lunchtime; a fire, typically small, was kindled. The old man cut the intestines free from the paunches, stripped them of their oozy contents between thumb and finger, then dropped them into the coals. There they sizzled and writhed for a scant few minutes. Still mostly raw, they were divided into small bits and handed out to the children. They ate them as an obvious delicacy and a treat, like sticks of liquorice. On the way home, we picked up a few other men who had stopped off at another spot to hunt. One of them owned a worn-out old shotgun (with barrel secured to the stock by well-bound wire) but only two shells. The men had managed to ambush a young doe, and were pleased enough. But they were greatly excited at my haul. Our arrival in camp just on dusk was heralded by the cry ‘plenty kangaroo!’ What a feast! I was redeemed! That night, a great bonfire was lit to celebrate. Camping in mulga scrub on a given clear night has considerable intrinsic charm – faint ocean-noises as the breeze blows through the fine leaves; the moist-dust smell of the leaves themselves; the smell of wood-smoke. All had gathered about the fire. There was a lot of banter and laughter around the fire. Then the song-man began his flat, nasal gravelly chant. At first quite loud and penetrating, the song descended by the gentlest of steps down, down to remain on a prolonged note so low and quiet that it mingled with the wind.

14

The Red Kangaroo in Central Australia

His chant came off and on until the fire had died away and the night had taken over. Here was the gratitude of simple man welling up in an eloquence beyond description.

2 Landforms, climate and vegetation

Australia is one of the world’s driest inhabited continents. Aridity generally increases with distance from the east coast such that most of the landmass is arid or semi-arid, producing sparse woodlands and grassland in the better-watered regions of the interior and elsewhere, deserts. Desert lands have an appealing starkness and simplicity. The very grain of the countryside is exposed to all. Ancient mountain ranges plunge and rear from the plains. Rocks and boulders lie tumbled at their feet. Dry watercourses break through mountain gorges to meander and die in the desert. Stunted trees stand mutely enduring the heat.

16

The Red Kangaroo in Central Australia

Biological survival in such a land is not simple. Plants and animals need behavioural and physiological adaptations, which must provide for two contrasting extremes – endurance of long harsh periods of drought and heat, and quickening after rain. Though sometimes so abundant as to cause great floods, rain is usually a scarce commodity. When it comes, plants and seeds long dormant quickly sprout, and animals breed promptly and put on fat. Bounty, whenever it arrives, must be exploited without delay. The very fibre of the land depends on it. We somehow expect small animals like birds and rodents, being short-lived, to be superbly attuned to conditions of feast or famine. What then of large and long-lived animals like the red kangaroo? The red kangaroo is unable to avoid the heat on a summer’s day by burrowing. Sexual maturity takes two to three years. And the animal requires a soft diet of green grass. Such an animal would seem to demand a gentle environment and not an arid one. To understand the way the red kangaroo lives in Central Australia requires description of the landforms, climate and vegetation there.

Landforms Australia’s ancient continental shield, more than 500 million years old, is exposed in Central Australia, forming a great plateau ~600 m above sea level. A complex and spectacular chain of equally ancient mountain ranges, notably the MacDonnell Ranges and Harts Range, rise from the plain for another 600 m and more. They form the east–west spine of the land,

2 : L andforms, climate and vegetation

17

a 400 km long series of parallel bluffs and ridges of gnarled quartzites, schists, gneisses, and granites of Cambrian12 and Precambrian13 origin. Here and there the ancient bedding of the original sediments flakes away to reveal ripples in the rocks, the result of gentle waves in an ancient sea. Large rivers, the Finke, the Todd and the Hale, and numerous creeks rise in this greater watershed and wind off to the south-east. They flow only after heavy rain. Near their headwaters, the rivers have well formed sandy beds, with tall river red gums (Eucalyptus camaldulensis) to mark their course. As the rivers proceed they become less marked, and eventually die in the Simpson Desert whose formidable dunes extend in military precision for kilometres, right up to the ranges themselves in places. Only the Finke, the last of the rivers, is powerful enough to cut through the desert. The Aboriginals have great regard for the Finke and lived along its length. The Finke was created, according to legend, by the great water serpent in his youthful travels, and they have an appealing name for this great river, the Larapinta. McDouall Stuart found it the pathway to Central Australia and named it after one of his benefactors, William Finke. It is doubtful if the Finke has reached Lake Eyre in historic times. Once it probably did so as part of the immense inland drainage system feeding the lake from the north – the Georgina, the Diamantina, the Cooper and the Macumba. However, in flush seasons, the Finke can be a mighty stream flowing for months at a time. Its force was measured during the floods of early 1967.

18

The Red Kangaroo in Central Australia

The Finke ran a bank almost a kilometre wide, and flowed with such strength, that the concrete pylons of the railway bridge snapped like carrots and the railway line bounced along the banks like a broken clock spring. More recently in 1973 and 1974, following the heaviest and most sustained periods of rain in the century of recorded history, the Finke, like several other rivers, flowed for the best part of a year. Great sheets of water lay in the swales between dunes right across the Simpson Desert. There really was a great inland sea. North of the MacDonnell Ranges lies the great Burt Plain, the home of the red kangaroo (Fig. 1.2). The Burt Plain is most distinctive, being the first large open area traversed by the Stuart Highway north of Alice Springs (Plate 4). The large, open, grassy plains near the ranges give way after a kilometre or two to extensive bands of mulga scrub (Plate 5). The soils of the open plains near the ranges are geologically young. Water running off the ranges accumulates there, improving the grass. Creeks rising in the ranges drain the plains and flood-out into the mulga scrub. The soils there are clayey sands termed ‘red earths’. The surrounding desert is composed of deep sands, which stretch virtually unrelieved to the north-west to the sea. Its sand-plain is clustered with hummocks of spinifex (Triodia spp.), the spiny tussock grass of the desert; trees are rare. The prevailing red colour of the soil is due to iron staining. On ~7000 km2 of this complex of open plains, mulga scrubs, creeks and spinifex, the ecology of the red kangaroo

2 : L andforms, climate and vegetation

19

was intensively studied. The area squarely straddles the Tropic of Capricorn. This study-area was chosen to contain some of the most fertile country of the area, and some of the least. It is depicted in the magnificent photograph taken from the satellite Gemini (Plate 6, but see also Fig. 1.2). The grain of the land stands out clearly: the MacDonnell Ranges and associated outcrops, the open plains, the mulga scrubs, the creeks and the spinifex sand-plain. The dry salt lake in the top left-hand corner of the satellite image indicates the lie of the land, to the north-west. The straight-line cutting northwards on the eastern edge of the Burt Plain is the Overland Telegraph and Stuart Highway to Darwin over 1500 km away. In times of drought, the red kangaroo is a common sight on the open plains along the road.

Climate The prevailing aridity of Central Australia is caused by its lying in latitudes where dry air descends from the upper atmosphere, is warmed adiabatically,14 so increasing temperatures and reducing relative humidity. For there to be any chance of rain, the stability of the prevailing high-pressure systems has to be disrupted by invading moist air, an unusual event, for there is no guarantee of rain. So stable are these atmospheric conditions that they are usually re-established within 24 hours of the passage of a southerly cold front, and can do so in only four hours.

20

The Red Kangaroo in Central Australia

Unlike large arid regions elsewhere in the world, no large obstructive landmasses or mountains lie to the north or south of the Australian arid region. Consequently, the rain-bearing low-pressure systems of the tropical and temperate zones rarely deviate from their paths tangential to the arid zone. To make matters worse, summers can be long and hot, though winters are pleasantly cool and sunny. The climate resembles, for example, that in the Chihuahuan Desert in Mexico. The prevailing aridity is often exacerbated by droughts, which can be long and severe. Perversely, rains can be torrential. The description of the land as one of feast or famine is quite apt. For example, the longest and most severe drought on record began in 1958 and lasted for six and a half years. This great drought was broken by the wettest period on record, which continues still.15 The most complete weather records in Central Australia have been kept at Alice Springs since 1884. Though winters can be pleasantly mild and sunny, summer can be very hot and the days long. The heat begins as soon as the sun gets over the horizon before 5 am and lasts after it has gone. Around 7 pm like an oven opening, the clear skies allow the earth to cool quickly; but there can be an awful lot of heat to be dissipated. Mean maximum temperatures exceed 32°C for five months each year. Maxima are often between 35 and 40°C. The maximum recorded is 47.1°C, though I personally have endured shade temperatures exceeding 50°C for weeks at a time out in the field – I was not necessarily in the shade all the time. To be in the sun

2 : L andforms, climate and vegetation

21

for more than a half-hour at a time was unbearable. Even with shoes on, the ground was too hot to walk on. It was so hot on one occasion in the Tanami Desert that a few hours’ work was possible from before sunrise until ~7:30 am, and then after sunset. The rest of the day was spent lying in the scant shade, just waiting. The uncertain rainfall comes from a tiered series of chance events. Two of them, summer and winter components, are edge-effects of tropical monsoons that bring rain to northern Australia in summer, and temperate low-pressure systems that bring rain to the south in winter. Sometimes they stray far inland. More usually, the two influences combine and bring heavy, widespread falls.16 A cold front emanating from a lowpressure system over the southern ocean to the south will collide with warm moist air invading from the tropics. Each low-pressure system providing this confluence may be 2000 km away from Central Australia in either direction at the time. The most unusual rainy events, though possibly the most biologically significant of them all, are the tropical cyclones. They brew off our north coast during summer. Mostly their paths are tangential to the arid zone also, but sometimes they change direction and sweep inland, right into the arid interior drenching great swathes of country. The average annual rainfall may come in a matter of a few days. Water is everywhere, and the countryside responds with lush and seeding herbage for many months. One year in about 10 to 15 receives enough rain from these chance events to keep herbage flourishing for most of the year, the rainfall being about double the average.

22

The Red Kangaroo in Central Australia

To illustrate the way in which chance climatic events bring rain to Central Australia, I will describe one that occurred in March 1967 when amazing amounts of rain fell in a few days over hundreds of thousands of square kilometres along a path 2000 km inland from Darwin. The land had one of its biggest drenchings on record. The great rains resulted from the collision of straying tropical air and a southern cold front. In only two days, Alice Springs received 14.4 cm of rain, half of its annual rainfall, and the desert to the south-west, 17.2 cm, more than the annual average (W. Hare, pers. comm.). The flooded Finke River at that time was described previously. It ran almost a kilometre wide at its highest, and flowed for six months that year, emptying itself into the Simpson Desert. Together with other streams it filled clay-pans and inundated swales between sand-dunes over great areas. To fly over the country at 10 000 m altitude was to see temporary ponds and lakes extending to the horizon on all sides all the way down to Lake Eyre. Water lay about for months, and the land had one of the flushest seasons in memory. The importance of such a rain to the wellbeing of the biota of Central Australia cannot be sufficiently emphasised. When such extraordinary rains invade, the land blooms. Many animals, rodents and small insectivorous marsupials usually rare, breed up.17 Swarms of birds appear (Plate 7), especially budgerigars (Melopsittacus undulatus) and zebra finches (Taeniopygia castanotis). Too often, however, the only indication of the bounty falling in the north or south of the continent are hot,

2 : L andforms, climate and vegetation

23

sticky conditions, or wispy curves of high stratus cloud, the tail ends of cold fronts. Sometimes, the cold fronts bring gusty conditions because the cold air sweeping in from the west thrusts under the warm air like a great wedge creating turbulence, which lifts dust higher and higher. On rare and magnificent occasions, gigantic walls of dust stretch from horizon to horizon, towering red and black colours into the sky. The calm before a dust storm and the grandeur of the rapidly advancing, gigantic wall of dust is unfortunately matched by the misery of the engulfing storm itself. Heat, sweat, wind squalls and swirling, choking dust cause great misery. A little rain often falls in its wake settling the dust and cooling the air. The smell of freshly wet dust is so distinctive. It can be detected a considerable distance downwind even by human beings, and of course you can see the storm clouds also. The smell brings such a gut-reaction that it is not hard to imagine its welcome and survival value to wild animals. Red kangaroos will follow storms, and so will cattle and camels (Camelus dromedarius) in that dry land. The essentially hot, arid nature of the climate is simply summarised in Tables 2.1 and 2.2, and the substance to the contours on Fig. 2.1 is that there are on average only 30 rainy days per annum in the Centre. Dry weather is usual on most days (Table 2.3). There is generally low rainfall at Alice Springs, from 20–25 cm per year, but the evaporation rates potentially 10 times as high as the rainfall, speak for themselves (Table 2.2). On average, it would seem a wonder that

24

The Red Kangaroo in Central Australia

Table 2.1. Average temperatures and relative humidity for Alice Springs based on 30 years of data from Bureau of Meteorology to 1966. Jan. Temperature (°C)

Apr.

July

Maximum

35.2

27.4

Minimum

21

12.1

Highest maximum: 47.1 Humidity at 3 pm (%)

Table 2.2.

26

Oct.

Year

19.4

34.8

28.3

3.9

14.7

12.9

Lowest minimum: –7.1

28

31

24

29

Rainfall (cm) and evaporation (cm) for Alice Springs c. 1960s. Jan.

Apr.

July

Oct.

Oct.– Mar.

Apr.– Sept.

Totals

Rainfall

4.4

1.0

0.7

1.8

19.2

6.1

25.3

Evaporation

30.4

18.8

9.4

23.9

160

80

240

Table 2.3. The probability that annual rainfall will exceed given amounts at Alice Springs, dates unknown. Amount (cm) Probability (%)

2

5

10

20

40

60

100

99

95

65

10

1.5

enough rain ever fell for plants to grow. Yet, of all the deserts, the Australian ones are well vegetated, possibly the result of those great rains that sometimes come by – the feast or famine. Pastures will commence growing if, in any week, the rainfall is equal to two-fifths of the potential evaporation i.e. if rainfall equals potential evaporation from the soil. If there is follow-up rain for an entire month, pastures grow very well. The rainfalls needed to cause such responses throughout the year are presented in Table 2.4

2 : L andforms, climate and vegetation

25

Figure 2.1: Rainfall contours for Australia. (Source: Bureau of Meteorology 2015 ).

along with the quite low chances of receiving such falls. Broadly speaking, the region can expect a little more than one month’s full growth of pastures in summer and a little less in winter, with twice as many false starts. About one in five years is expected to be a bumper year (‘feast’) and an equal number drought-stricken (‘famine’) (Table 2.5). The average year has just under four months’ growth. Occasionally, there are runs of wet years. The really wet runs were 1920–1923, 1945–1950, 1966–1969 and 1973–1975. On the other hand, runs of dry years produce severe droughts as from 1892–1893, 1928–1930, 1934– 1935, and the worst of all from 1958–1965.

26

The Red Kangaroo in Central Australia

Table 2.4. Rainfalls adequate for pasture growth, their probabilities and lengths of growing periods (Summer = Oct.–Mar.; Winter = Apr.–Sept.), dates unknown. Jan. Weekly values

July

Oct.

Rainfall (cm)

2.9

1.6

0.7

2.2

Probability (%)

38

26

28

24

Expected growing periods (months) Monthly values

Apr.

Summer: 2.0

Winter: 1.6

Rainfall (cm)

6.1

3.7

1.2

4.0

Probability (%)

21

15

20

19

Expected growing periods (months)

Summer: 5.0

Winter: 4.0

Table 2.5. The chance that any year will be wet enough for pastures to grow for given periods. Calculated from rainfall records at Alice Springs, 1921–1960. Note that the probability has two peaks, one on a period of eight months and the other on three months (‘feast’ or ‘famine’)

Period (months) Probability (%)

0

1

2

3

4

5

6

7

8

2.5

2.5

17.5

22.5

17.5

20.0

10.0

2.5

20.0

To highlight the variability and scarcity of rain in some years, the statistics from a rain gauge in my study-area at Hamilton Downs are given in Table 2.6 for 1961, a year of severe drought. These figures show how the climate produces a hard environment in Central Australia, especially for a herbivore like the red kangaroo.

27

2 : L andforms, climate and vegetation

Table 2.6.

Monthly rainfall at Hamilton Downs 1961.

Months

Jan. –Mar.

Apr. –Jun.

Jul. –Sept.

Oct. –Dec.

1.6

6.6

0.0

0.3

Rainfall (cm)

Total 8.5

My study had several dry periods in it, its commencement coinciding with the start of the great drought in 1958. To compare the severity of droughts in different years and in different seasons (a month’s drought in summer being more severe biologically than in winter), a Drought Index (Newsome 1966a) was calculated like a profit and loss account from rainfalls and potential evaporation. Its derivation is explained in Chapter 4, and is used to measure the effects of drought on breeding in the red kangaroo.

Vegetation Patterns in the vegetation of Central Australia are well formed, the various plant communities being distributed according to soil types and moisture regimes. Perennial grasses grow in the better watered places, Mitchell grass (Astrebla pectinata) on clayey soils adjacent to the ranges (Plate 8), neverfail (Eragrostis setifolia) (a favourite of the red kangaroo) in depressions called ‘gilgais’ (Plate 9), and curly windmill grass (Chloris acicularis18) in creek beds. Ephemeral grasses spring up after rain. Different pastures grow depending on whether the rain is in summer or winter. The former promote growth of short grasses and the latter succulent but less nutritious

28

The Red Kangaroo in Central Australia

broad-leafed forbs (Perry 1960). The commonest forbs are the white and yellow daisy (Helipterum floribundum and H. charsleyae19). Thus, spring is the time for spectacular shows of wild flowers in the Centre, after winter rains (Plate 10). Mulga, the commonest tree (Plates 5 and 11), is widespread, growing on the hills, the plains and in the desert. However, it grows best on certain widespread clayey sands termed ‘red earths’. The shape of a mulga tree and its tendency to grow in groves help improve the tree’s water supply. Leaves and limbs are aligned vertically so that water drains down to the base of the trunk. In dense mulga woodlands, grove patterns tend to follow the micro-contours of the land. Land between groves slopes slightly so that water drains off and into the groves. The hardy spinifex, the abundant spiny tussocks of the desert (Plate 12), is also nicely adapted for the aridity. Its roots can extend 15 to 20 m and more into the deep sands seeking moisture; the long spiny leaf has reduced surface area by rolling into a fine cylinder with all its stomatal pores20 lying protected deep in a fine groove running its entire length. The genus is probably ancient. After widespread rain, green grass grows everywhere. Its distribution shrinks drastically during droughts to the flood-outs of creeks and the gilgais on the open plains. Only there can red kangaroos find food at such times. The correlation between topography, soils and vegetation have enabled CSIRO scientists to classify the countryside into units termed ‘land-systems’ (Christian & Stewart 1953). Accordingly, Perry et al. (1962) have mapped much of Central Australia, including the red

2 : L andforms, climate and vegetation

29

kangaroo study-area, the Burt Plain. Their classification proved highly suitable for studying red kangaroos and so they are briefly described under topographical headings here. Each land-system is given its name so that readers may refer to the original descriptions for greater detail. 1. Watercourses (McGrath land-system) There are several watercourses on the study-area (Fig. 2.2). Their floodplains vary from 1 to 2 km wide, sometimes more, are usually well grassed, but almost treeless. The upper third of these watercourses has a prominent channel lined with tall river red gums. Sheet-flow of water is usual across the open plains in the middle third, while below this, the water floodout, trees grow close together providing excellent shade, and grass stays green long into drought.

Figure 2.2: Land-systems in the Burt Plain.

30

The Red Kangaroo in Central Australia

2. Open Plains (Undippa, Alcoota and Hamilton land-systems) These three land-systems lie adjacent to the MacDonnell Ranges and receive run-on water from them (Fig. 2.2). Consequently, native pastures grow well. The first of these systems are large treeless plains with blackish clay soils, which crack when dry. They are dominated by Mitchell grass. In order, the other two are sizeable grassy plains surrounded by mulga scrub, and medium-sized grassy plains and clumps of mulga, which form a mosaic. Gilgais are scattered about these plains, and are a key feature of them. They form because the clayey soils swell and shrink as the moisture content varies. Some gilgais are quite small, only a metre or so across, while others may be 10 to 20 times that size. Elsewhere in Australia they are sometimes called ‘crab-holes’. Gilgais collect water during rain so that succulent grasses grow there, notably neverfail, a great favourite of the red kangaroo. It, too, stays green long into a drought, especially if cropped short by cattle or sheep. Another dominant plant growing in the bottom of the deeper gilgais is nardoo (Marsilea exarata) (Plate 9). This prostrate plant looks like a four-leafed clover but is in reality closely related to the ferns. Its small seeds (strictly sporocarps) were ground into flour by Aboriginals to make a damper to feed the starving explorers Burke and Wills on Coopers Creek. Other grasses can grow abundantly on the plains after good rains: kerosene grass (Aristida spp.), oat grass

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31

(Enneapogon spp.), Flinders grass (Iseilema spp.), and blue grass (Bothriochloa decipiens). One annual, button grass (Dactyloctenium radulans), grows densely after rains, especially in areas that have been overgrazed and trampled by livestock (Perry 1960). The small daisies mentioned previously that proliferate after winter rains are also excellent invader species. After the big drought (1958–1965), the giant yellow daisy (Senecio magnificus) rarely seen beforehand became common in disturbed areas. The few trees growing are mainly mulga, but there are also scattered individuals of the gnarled corkwood (Hakea intermedia), the weeping ironwood (Acacia estrophiolata), and bloodwood (Eucalyptus terminalis21). 3. Woodlands (Boen, Bush Park and Kanandra land-systems) Dense, almost pure tracts of open mulga woodlands extend beyond the open plains and creek systems (Fig. 2.2). Mulga trees may be 5 to 10 m tall, and grow either scattered randomly or in grove-patterns (Plate 5). For all purposes here, these woodlands are not treated separately. The dominant grass, woollybutt (Eragrostis eriopoda), grows sparsely in open spaces. Other herbage becomes temporarily abundant after rains, but green herbage of any kind is a great rarity during drought, the woodlands drying out before the open plains and watercourses. Trees similar to those on the open plains grow thinly scattered through the

32

The Red Kangaroo in Central Australia

woodlands, but predominate in small areas right at the foot of the ranges. 4. Sand-Plains and Sand-Dunes (Singleton, Simpson, and Titra land-systems) These vast sand-plains and dune-fields are called desert (Fig. 2.2), though I suppose it is misleading to do so. Australian deserts are not barren like the Sahara, but are really quite well vegetated. Spinifex often grows so thickly that it is impossible to walk between clumps without being spiked by its leaves. Nutritious grasses (kerosene grass and woollybutt) do grow, especially after rain, and there are usually some trees in sight (e.g. mulga and coolabah Eucalyptus coolibah, witchetty bush Acacia kempeana, and Senna spp.). Scalds, saltpans and even salt lakes exist between the sand-dunes or in larger basins. Saltbush (Atriplex nummularia) and the shrubby tea-tree (Melaleuca glomerata) may grow along the margins. These depressions fill with water after rain. The uses which red kangaroos make of these various landforms, playing one off against the others as the seasons change, are described in later chapters.

3 Distribution and abundance

‘Kangaroos by the thousand’ is the description many graziers give of their land. It sounds a complete overstatement; but I have seen such a mob myself as noted earlier in Chapter 1. Without doubt, there were well over a thousand red kangaroos in that great horde. During five years of my study, other mobs were encountered, but nothing to equal this. One other group was 500 strong, a few groups held 150 red kangaroos, and there were several others in the hundreds. What could be the reason for such congregation? Could they be expected at any particular times of year or season, or in any type of country more than another? My study of distribution and abundance of

34

The Red Kangaroo in Central Australia

red kangaroos near Alice Springs set out to seek the answers. The kangaroo’s mobility made a large study-area imperative, and aerial survey, the appropriate technique (Plate 13). The plains country north of the MacDonnell Ranges had three basic kinds of vegetation growing in bands away from the ranges. Open grassy plains flanked the ranges and extended over 5 to 10 km from them. Then a broad sea of almost uniform mulga scrub (woodlands). Beyond lay the proper desert (sand-plains and sand-dunes). Cutting across these bands were watercourses that rose in the hills and flooded out into the mulga scrub. These landforms and their vegetation were described in detail in Chapter 2. The western half of these plains was named the Burt Plain by McDouall Stuart (Plate 6). In fact, the thick mulga scrub greatly vexed Stuart, tearing clothing and other gear, and spiking the horses. About 7000 km2 of it was chosen for my own aerial surveys. For comparison, and for more accurate estimates of numbers, the area was divided into blocks each enclosing one predominant landform or another. Thus, there were five blocks over open plains, two over mulga scrub woodland, one large one over the desert (sand-plains and sand-dunes) and two others enclosed creek communities (water-courses). Two of the blocks over open plains also had major creek systems within them (Fig. 3.1). Many hours were flown in a one-engine high-winged Cessna, experimenting with the best height above ground and the best speed for counting kangaroos. The altitudes tested were from just above the ground, a bit risky, to

3 : Distribution and abundance

35

Figure 3.1: Aerial survey blocks where counts of red kangaroos were undertaken during drought in October 1961, and after rains fell in April– May 1962 and May–June 1966. The numbers relate to those shown in Table 3.1. The map has been simplified from Newsome (1965b) . Blocks 11 and 12 were only surveyed in October 1961.

~300 m up. Speeds varied from near still or stall speed, 60 to ~180 km/h. The very best combination for seeing kangaroos was, unfortunately, the most dangerous: 15 m above the ground and 65 km/h. The view was magnificent, and the ride, an armchair. We were just above the trees, full flap was on the wires, and the stall-warning buzzer was constantly sounding. There was just no margin for error. The compromise finally struck was 90 m above the ground and 130 km/h, and on one windy gusty day, it saved our lives. We had just flown one leg north to south over the mulga scrub and were turning to fly the next. Just as we banked close to the ranges, an eddy caught the plane and it sank us like a stone. Only the astonishingly

Habitat type

Mulga scrub, open plains, and watercourse

Open plains, watercourse, and mulga scrub

Watercourse

Open plain

Open plain

Block

1. Bond Springs

2. Burt Plain

3. Amburla

4. Mt Chapple

5. Mt Hay

Abundant

Sparse

Common

Spares

Common

Green herbage

23.02

4.89

7.79

3.39

5.19

Mean nos. kangaroos per square km during drought in 1961

Sparse

Sparse

Abundant

Common

Abundant

Green herbage

1.32

1.86

4.40

6.19

5.14

Mean nos. kangaroos per square km after drought in 1962

0.55

3.83

3.19

5.34

1.66

Mean nos. kangaroos per square km after drought in 1966

Numbers are given for a follow-up survey after rain fell in May–June 1966. Blocks 11 and 12 were only surveyed in October 1961. Data are from Newsome (1965b) and Newsome et al. (1967).

Table 3.1. Estimates of the number of red kangaroos during drought in October 1961 and after drought in April–May 1962 in Central Australia.

36 The Red Kangaroo in Central Australia

Watercourse

Open plains and mulga scrub

Mulga scrub and watercourse

Mulga scrub and spinifex sand-plain

Spinifex sand-plain

Desert

Desert

6. Charlie Creek

7. Hamilton Downs

8. Ceilidh

9. Yambah

10. Desert Block

11. Derwent

12. Mt Wedge

Rare

Rare

Rare

Rare

Rare

Common

Abundant

1.03

0.98

0.44

0.51

1.16

6.03

21.05

–

–

Common

Common

Abundant

Abundant

Abundant

–

–

0.85

4.09

7.71

13.00

3.52

–

–

0.282

4.99

5.19

5.09

5.72

3 : Distribution and abundance

37

38

The Red Kangaroo in Central Australia

quick action of my very favourite pilot, Colin Beck, saved our lives. Quick as a flash, he banged the throttle fully home, full power was on, and the plane put into a dive. We levelled out a few metres above the trees. It seemed ages, but I suppose no more than a second or two at most had passed before we knew we were safe. But, in those previous few seconds Colin had not only completely saved the situation, he also had the presence of mind to aim the plane for a gap between two trees just in case we did not make it. That way, the wings would have sheared off first, giving us a better chance. Afterwards Colin was still unruffled; but his passengers had turned shades of green. During a survey, a buzzer sounded every 10 seconds and we wrote down how many kangaroos we had seen in that time. Thus, in each survey block, we laid down a string of quadrats for which we had individual counts of kangaroos. To calculate densities, or number per square kilometre, we needed to know the width of quadrats. Kangaroos were harder to see in mulga scrub than on open plains. The width of quadrats was therefore narrowed in an attempt to equalise our ability to spot kangaroos in different terrain. Three widths were chosen, one for scanning open plains, one for sparsely wooded regions, and the closest in, for mulga scrub. The widths they represented on the ground were calculated by repeatedly flying lines adjacent to a straight stretch of the Stuart Highway where it crossed the open plain. During these flights observers would sight through marks on the wing struts at ground-markers set in lines 33.3 m apart. Over open plains the width of any quadrat was estimated

3 : Distribution and abundance

39

at 450 m, over wooded regions 400 m, and over mulga scrub 270 m, minus 18 m obscured by the plane. Throughout the surveys, the areas to be flown were selected randomly by dividing each block into lanes 500 m wide. Where we expected kangaroos to be common, e.g. along creeks and on open plains in drought and in the mulga scrubs after rain, 20–25% of lanes were flown. Elsewhere, only 10% were flown. Lanes flown were separated by 1.6 km to avoid counting the same kangaroo twice. Because kangaroos appeared to congregate near open plain areas during drought but disappeared a few days after rain, the plan was for two surveys. Our hypothesis was that changes in the availability of green herbage caused the change in distribution of the kangaroos. An alternative explanation for the disappearance of kangaroos after rain was suggested by a cattleman from the channel country of far western Queensland. He believed them to be escaping from blood-sucking sandflies (which breed up after the rain). Such flies are rare in Central Australia (but not the channel country), so we stuck to our hypothesis of the food supply. The abundance of green herbage varied from block to block in each survey. Where such herbage formed an almost continuous green carpet, it was termed abundant or common; where it grew in scattered pockets, it was termed sparse; and where it could not be seen, it was termed rare (Table 3.1). The first survey was conducted in October 1961, six months into a drought, and the second in April– May 1962, four months after heavy widespread rain had broken the drought. During the former, 2600 km of lanes were flown and 1017 kangaroos seen in 7212 quadrats.

40

The Red Kangaroo in Central Australia

During the latter, 3500 km of lanes were flown and 1102 kangaroos were seen in 9748 quadrats. About 75% of kangaroos were seen in ones, two’s or three’s, but there were a few groups of 10 or more, and one, even of 22 animals. The same tract of land was flown in each survey of total area 6840 km2, although two blocks (11 and 12) were surveyed only in October 1961 (Fig. 3.1). The estimated density of red kangaroos on any block was calculated by taking the average number per square kilometre in the quadrats of each lane, and then averaging across lanes. Since the sizes of blocks were known from the map, the total number of red kangaroos per block could be calculated. Numbers could be lumped for blocks where the food supply was similar, and new average densities calculated (Table 3.1). I have taken time to describe the methods and analysis of the aerial surveys because, as in all science, the results are only as good as the methods. I have not assumed that all kangaroos in the lanes were spotted, but that a relatively constant proportion of them were because the width of quadrats changed with visibility. A study by Dr G. Caughley at The University of Sydney confirmed this major assumption. But, it is sufficient here to say that, since only six months separated my first two surveys, population numbers should have changed little in that time. Changes in numbers could therefore be interpreted as changes in distribution. These changes highlighted in no uncertain way the primary importance of green herbage for kangaroos to eat, a fact corroborated by an independent study by the botanist Mr G. Chippendale (Chippendale 1968b).

3 : Distribution and abundance

41

The highest density of kangaroos, 21–23 per square kilometre, was associated with only 5% of the land, one open grassy plain and one particular creek, both close together near Mt Hay (Plate 4), where food was common. On about equal portions of the remaining land, food was either sparse (some plains and creeks), or rare (mulga and desert), and the kangaroos’ density varied accordingly, 5.4 and 0.51 per square kilometre (Table 3.1). When numbers are sorted by habitats, two particular ones were favoured: open grassy plains and the flood-outs of creeks (watercourses) (Table 3.1). Table 3.1 illustrates also that red kangaroos were almost absent in about half the study-area, comprising some of the mulga woodlands and the desert. The land flanking the ranges where woodlands and open plains formed a mosaic (42% of study-area) held surprisingly large numbers of kangaroos, over 50% of the total estimated, though the density was well below the peak and was ~5.19 per square kilometre. The association of kangaroos with shady trees was clear cut (Plate 14). During the hot summer, they sheltered all day in the shade emerging to feed in the cool of evening, or, on real scorchers when the temperatures rose over 40°C, not until after dark. There was a clear edge effect on the open plains where kangaroos were so dense they spent the day sheltering in the fringing mulga woodland. Thus, the most favoured land of all was in the flood-outs of creeks. With the extra supplies of run-on water from the rains, mulga trees grew densely, almost closing the canopy, and green herbage flourished there for many months after it had dried up elsewhere.

42

The Red Kangaroo in Central Australia

These specially favoured regions represent a very small but most important part of the kangaroo’s environment. As will be seen later in Chapter 7, Aboriginal peoples were well aware of this fact for it bore a great influence on their lives. After the rain, the kangaroos were redistributed among the various habitats (Table 3.1). The grassy plains so favoured during drought were almost abandoned. So too were the creek systems, except in their lower reaches where now green herbage grew well beyond the floodouts and into the surrounding mulga scrub as well. In fact, kangaroos were all through the mulga scrub, which held the highest density of animals at the time, up to 13 per square kilometre. But, once more, the mosaic of open plains and patches of scrub held large numbers of kangaroos because of the favourable position of food and shelter there just as in the true mulga scrub. The open plains, because of the scarcity of shelter, still contained few kangaroos despite the food (Fig. 3.1). That the red kangaroos chose areas where food and shade were abundant was further illustrated from follow-up surveys in May–June 1966. In this case, the surveys were completed some four years after the initial drought had broken, although little rain had fallen between 1962 and 1966. Indeed, annual rainfalls around Alice Springs during this period were among the lowest received there, and in 1963 and 1964 only 12.1 and 9.6 cm of rain fell, respectively. Even less rain fell elsewhere in Central Australia. This drought lasted in most places till 1966, although there was some good rain in August and December 1965. The drought was completely broken by

3 : Distribution and abundance

43

good rains that fell in February and again in June 1966. Thus, the follow-up survey in May–June 1966 allowed us to see what effect, if any, the long drought had on kangaroo distribution. It also provided the chance to see whether numbers had changed, with the expectation that kangaroo numbers would have fallen since the surveys in 1962. During the 1966 survey ~1818 km were flown along the same survey blocks (Fig. 3.1). A total of 430 kangaroos were seen in 229 of the 5083 quadrats surveyed. By comparison, in 1962, 9748 quadrats were scanned and 1102 kangaroos were counted in 534 quadrats. Thus, kangaroos were absent from over 94% of the survey quadrats in both surveys. By comparing the mean number of kangaroos seen per square kilometre in 1962 to 1966, we found that numbers of kangaroos fell significantly for blocks, 1, 7, 8 and 10 (Table 3.1). The total number of red kangaroos estimated to be on the study-area was 2817 in 1966 compared to 4914 in 1962. This indicated that drought reduced kangaroo numbers on the entire study-area to almost a half. The decline was not distributed across all the blocks, but this may have been related to the fact that it was much easier to spot kangaroos in the 1966 survey, as the long drought had thinned out the mulga scrub. It is quite likely, therefore, that the decline was distributed all over the blocks but that the aerial surveys were just not accurate enough to demonstrate it. As in the 1962 survey, most of the kangaroos seen in 1966 were living in the mulga woodlands. There was on average about five kangaroos per square kilometre on

44

The Red Kangaroo in Central Australia

blocks 6, 8 and 9, which were dominated by mulga woodlands. By contrast, there were less than two kangaroos per square kilometre on blocks 1 and 5, where open plains predominate. The large numbers of kangaroos on blocks 2 and 7, which are largely open plains, seem to contradict this; however, the western ends of these blocks are mostly mulga woodlands and the kangaroos congregated there (Table 3.2). Overall then, the three aerial surveys demonstrate the red kangaroo’s primary need for food above all, and the favourability of adjacent shady trees. Indeed, during drought, when herbage was scarce in the broader mulga woodlands, red kangaroos were mainly found in the fringing mulga trees close to the open plains and floodout creeks where herbage was available. After the rains fell, the kangaroos concentrated in the broader mulga woodlands where rain had provided food and shelter side by side. I was able to calculate the net movement of kangaroos from the open plains to the mulga scrub after rains, and it amounted to 3 to 4 km. Individual movements would be much greater over time, of course; we often flew over areas where kangaroos had been Table 3.2. Density of red kangaroos on two types of country (±standard error). Modified from Newsome et al. (1967).

Block

Mean nos. of kangaroos seen per square km Open plains

Mulga woodlands

2. Burt Plain

1.74 ± 0.46 (n = 10)

14.33 ± 5.64 (n = 4)

7. Hamilton Downs

2.38 ± 0.84 (n = 18)

10.53 ± 1.90 (n = 9)

3 : Distribution and abundance

45

living, noticed because of the abundance of hip-holes22 dug in the earth (Plate 15). There is, then, a tidal movement of kangaroos to and from the open plains, which depends on the seasons. With green food available everywhere, the animals prefer to remain in the broader mulga scrub. As it dries up during drought, the kangaroos drift towards the open plains and watercourses where green grass alone grows in any quantity. Perhaps, though, you have noticed an anomaly. How can there be green grass on open plains during drought when there is so little after rain? The answer lies with the effect of cattle on the range. After rain, the grasses on the plain mature, seed, and die back, leaving little for kangaroos to eat. Before the kangaroos return, however, cattle graze the tall dry grass down forcing perennial grasses to tiller. In this way a ‘marsupial lawn’23 is created to suit the kangaroos. The increase in density of kangaroos out from water during drought is also regarded as such an effect. The implications of the availability of this marsupial lawn on the reproductive capabilities of the red kangaroo are discussed in the next chapter.

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4 Reproduction

When our red kangaroo studies began in 1958, almost nothing was known of an important aspect of the species’ ecology, its reproductive biology. In fact, little was known about breeding in any desert mammal in Australia at that time. Studies in Australian mammalogy were in so early a stage then that, incredibly, the only direct clues about the red kangaroo’s breeding were over 30 years old. What was worse, they contained apparent contradictions. For example, Professor Wood Jones, a British scientist and naturalist who spent considerable time in Australia in the early 1900s, recorded some female red kangaroos with pregnancies lasting 30 to 40 days, but some females observed mating were found later with young so large as to indicate a considerably shorter gestation period.

48

The Red Kangaroo in Central Australia

Further, one female gave birth after 11 months’ separation from a male. Wood Jones had supposed that the female red kangaroo stored sperm in its genital tract, like bats. The correct answer was even more amazing than that, though it was many years later that the mechanism was described in full by Professor G.B. Sharman. In a classical study of a small wallaby called the quokka (Setonix brachyurus), Sharman described how the female mated a few days after a young was born and had entered the pouch (Sharman 1954). The new embryo developed for less than a week into a hollow, pinhead-sized ball of cells termed a blastocyst, 24 an early stage in the development of any vertebrate embryo. Development of the blastocyst then ceased, but only for so long as the young in the pouch suckled continuously. When sucking became intermittent during weaning of the joey, pregnancy resumed. The interval between fertilisation and birth was increased from about a month to about seven months in this way. The process was first termed ‘delayed implantation’, but renamed ‘embryonic diapause’. Both terms are a little misleading. The process is so complex, however, that no simple term describes it adequately. In fact, it would be correct to talk of processes rather than one process, as the burgeoning studies of kangaroo reproduction continue to demonstrate. Now, years after its initial discovery, we have become a little blasé about this remarkable feature known in some other kangaroos and wallabies also. Besides, delayed implantation was already well known in rodents, even in the house mouse (Mus musculus). But the truly remarkable

4: Reproduction

49

fact in these wallabies and kangaroos was the duration of the process. The embryo ceased to grow for only eight days in the house mouse, but may do so for almost as many months in the red kangaroo. The suckling stimulus of the young somehow triggers appropriate responses in the female’s endocrine system25 to halt the progress of pregnancy.

Field studies In 1958, the first samples of red kangaroos were collected in Central Australia to study their reproductive cycle. Microscopic study of ovaries, uteri and lateral vaginae of pregnant and lactating females demonstrated similarity between the reproductive cycles of the red kangaroo and quokka. Later studies of captive red kangaroos confirmed that (i) the oestrous cycle and pregnancy lasted ~35 and 33 days respectively, (ii) that the mother mated soon after birth, and (iii) the resulting young lived for about eight months in the pouch. If the young dies or is removed experimentally, a new young is born 31 days later, a period a few days shorter than the usual pregnancy. If the young is reared, birth is delayed for around 230 to 252 days. The embryo remains as a blastocyst dormant in a fold of the uterus. To test whether such fertility prevailed in the wild, we regularly shot red kangaroos for sampling over a period from 1958 to 1963. The proportion of youngat-foot (9–12 months old) in the population was also counted to check the efficiency of reproduction. Methods of collection were as follows.

50

The Red Kangaroo in Central Australia

Two sampling areas were chosen each with open plains and creek systems. The Burt Plain between the Burt and Harry Creeks ~50 km north of Alice Springs up the bitumen was one area. It lay on Yamba Station and was ~650 km2 in size. The other lay ~30 km to the south-west on Hamilton Downs, Milton Park and Amburla Stations and immediately north of the MacDonnell Range. This area was ~1000 km2 in size, and was separated from the broader Burt Plain by a dense band of mulga woodland (Fig. 4.1). Every six weeks or so, kangaroos were shot at night along transects ~45 and 65 km long on the two sampling areas respectively. The rifle used was a Hornet 0.22 fitted with a Pixar ×4 telescopic sight, the rifle being accurate and heavy enough without making too much noise and the scope being good for night work. Kangaroos were located with two spotlights from a Land Rover.

Figure 4.1: Sampling locations for red kangaroo reproductive studies.

4: Reproduction

51

Now, we could never know how many kangaroos would be seen in a night’s work, whether a hundred or a thousand. A completely random system of selecting study animals was impossible. Yet an unbiased method was required to ensure that we did not select just the largest or closest animals. There may be some quality associated with largeness or closeness in kangaroos such that their selection would not represent reality. For example, large animals, being old, could be reproductively senile, and close animals may be sick or lame. The object is to sample all types in the population. The closest approach to that ideal was to take a stratified random sample, taking randomly selected animals from groups of kangaroos as they were encountered. Most groups were of five or fewer animals. So we randomly selected one from every pair or trio of animals, one or two from groups of four or more, and even a third if the group stood for long enough and kangaroos were in short supply. Consecutive singles were treated as a pair for this purpose. To do so, both driver and passenger worked spotlights. When a group was sighted, the driver manoeuvred quietly into position to shoot. The passenger then counted the number in the group and quickly consulted a card of random numbers specially prepared for groups from two to 10. If the card indicated No. 2, the second kangaroo from the left was shot, if No. 5, the fifth, and so on, depending on the size of the group. If kangaroos were scarce, as they often were after rain, a second and even a third randomly selected kangaroo was shot from large groups. Again, this depended on the size of the group and on good management. The good

52

The Red Kangaroo in Central Australia

management lay in being a good shot and, fortunately, Mr Dean Stephens, my offsider, was an excellent shot. This technique worked well in drought when large numbers were out feeding on the plains at night, and samples were obtained readily in seven to 10 nights’ work, 20 animals being examined per night. After good rains, however, samples often took a month to obtain, the kangaroos being so scarce that all animals seen were hunted. There were several categories of reproductive females during drought (see below) and so more mature females were shot on each sampling area after the initial 50 animals were taken. Since females outnumbered males about three to one (see Chapter 6), an extra 10 to 15 animals were usually required on each area. These were selected randomly also, but small females were ignored. As we drove along, we also counted the number of young-at-foot in every 100 animals. It was not possible to count the other animals by sex because in Central Australia males and females do not have distinctively different coat colours in summer, though some females turn blue in winter (see Chapter 2). The body of each animal was measured and weighed. Reproductive organs were labelled and preserved in 10% formalin. Pouch-young were also measured, weighed and sexed (Plate 16). If nipples were exuding milk or brown fluid as lactation waned, or were enlarged, that was noted. Four molars erupt in red kangaroos at different ages (see Chapter 6), and so the molar eruption pattern was also noted. About 20% of the skulls were kept for subsequent study.

4: Reproduction

53

The effects of drought on female reproduction Almost from the start of field sampling, it was clear that red kangaroos did not breed continuously in Central Australia. During drought, adult females were found without young and with no sign of reproductive activity (no follicles, corpora lutea or pregnancies). They were in anoestrus,26 presumably caused by poor nutrition. Other females were found still in breeding condition and even lactating, but with enlarged but empty pouches. Apparently, pouch-young were dying during the drought. Indeed, two females were found with dead young in the pouch. Both were pregnant. With the suckling stimulus removed, growth of the blastocyst resumed just as would have happened should the joey have survived its full eight months of pouch-life. Unimplanted blastocysts acted therefore as reserves, and fresh crops of young were born during the beginning of the drought. The ovaries of some females several months into drought indicated that the cycle of birth, mating, suckling, early death of young and its prompt replacement through resumption of pregnancy was repeated a few times at least. Presumably after several attempts to rear young, reproduction ceased so that the female became anoestrus. The extraordinary method of entering anoestrus in red kangaroos is described below. For the present, let us consider the mortality rate of young and the rate at which females became anoestrus during a long drought. After drought-breaking rains, all mature females bred, and a crop of young were born about five weeks later. The

54

The Red Kangaroo in Central Australia

proportion of anoestrus animals was plotted against a Drought Index,27 as it increased. The results demonstrate that non-breeding response appeared to increase with the Drought Index (Fig. 4.2).28 Similarly, the proportion of any cohort of young that did not survive to become young-at-foot increased with the Drought Index (Fig. 4.3). Analyses of the responses shown in Figs 4.2 and 4.3 revealed that half the young died in the pouch after only 1.5 to 2.5 months of drought, and that half the females ceased breeding after three to five months of drought. Both responses came sooner in summer than in winter droughts, and sooner on the Burt Plain sampling area than on Hamilton Downs. To be exact, drought was 1.5 times more effective in inducing anoestrous on the Burt Plain than on Hamilton Downs (the reason was overgrazing by cattle and this will be explained further below). Thus, prolonged drought curtailed breeding severely. Young grew more slowly, sexual maturity was delayed by six months, mothers suckled young for two weeks longer and no young survived eight months of drought. Only about one-sixth of the females remained in breeding condition during this period. As a side note, I doubt if drought ever prevails everywhere throughout a large and varied region for long enough for all females to cease breeding. Some green grass must survive somewhere due to small local storms, and some kangaroos must find it. Indeed, in 1966, after the long drought of 6.5 years’ duration broke, I saw one female with a young-at-foot, which must have been born during that drought. But breeding must have been a very rare event then indeed.

4: Reproduction

55

Females in anoestrus (%)

100

80

60

40

20

0

0

4

8

12

16

Drought index

Figure 4.2: The relationship between the percentage of females in anoestrus and the Drought Index. Data are from Newsome (1966b) . 100

Young mortality (%)

80

60

40

20

0

0

4

8 Drought index

12

16

Figure 4.3: The percentages of young-at-foot that died plotted against the increase in index of aridity during life in the pouch (referred to as the Drought Index on the x-axis). The values were calculated by comparing the difference between the number of pouch young less than six weeks old to the number of young-at-foot in the population about eight months later, with the increase in the index of aridity (Drought Index) calculated for the appropriate intervals. Data are from Newsome (1965a).

56

The Red Kangaroo in Central Australia

Female reproduction – entering anoestrus Among females shot during drought were some in a most unexpected reproductive condition, which surprised us greatly. Reproductive studies of macropods up till then showed invariably that the ovaries of suckling females contained a corpus luteum29 in an arrested state of development, resulting from the customary oestrus following birth. But some kangaroos from Central Australia were found with absolutely no sign of such corpora lutea; yet they had young in their pouches. At first, it was thought that a mistake had somehow been made in labelling the wrong reproductive system in the field. But, there were just too many ‘mistakes’. In fact, we had stumbled onto a fascinating and unknown mechanism for reproduction bypassing the drought. Females could enter anoestrus and yet suckle young, a combination unknown in other mammals at the time. For example, during anoestrus induced by starvation in the rabbit, lactation fails and the young dies. Further inquiry revealed that females pregnant or with newborn young were clearly not preparing or prepared for the customary oestrus. What is more, the microscopic structure of the uterus shows a striking comparison between one clearly in a pregnant state and the other undergoing anoestrous changes (Fig. 4.4). The spiral uterine glands so enlarged at oestrus were shrinking and the cells lining the uterine lumen were square-shaped instead of columnar. Indeed, no follicles were developing in the ovary of the non-pregnant uterus during the late stages of pregnancy.

4: Reproduction

a

57

b

Figure 4.4: Comparison of cells lining the uterus of female red kangaroos. (a) Shows the cells lining the uterus of a lactating female red kangaroo in anoestrus with very shrunken uterine glands. (b) Shows the cells lining the uterus of another lactating female red kangaroo shot at the same time but with abundant, large, uterine glands. Figures are from Newsome (1964a) .

Presumably, secretion of hormones from the anterior pituitary had ceased while those from the posterior pituitary in control of lactation (e.g. prolactin) were secreted. That the pregnancy continues under such circumstances strengthens the belief that the latter part of pregnancy is under feto-placental30 control and independent of secretions from the pituitary31 and ovary. In other words, presumably starvation or poor nutrition had reached such a level that follicle stimulating hormone secretion failed. Anoestrus would follow. Anoestrous lactating females were not freakishly uncommon. Of 145 females suckling young at the end of droughts, 50, over a third, were anoestrus. Since the

58

The Red Kangaroo in Central Australia

mortality of young is so high during drought it is clear that this peculiar reproductive trait of red kangaroos is important to the survival of the species. Any young still alive at drought’s end has a running start.

Female reproduction – breeding after rain When drought-breaking rains fell and green herbage flourished once more, the non-lactating, non-breeding females all promptly bred within the week, and lactating females with a blastocyst continued to suckle their young. But what happened to the lactating anoestrous females? In some placental animals,32 e.g. humans, ovulation is suppressed during lactation; but it is not so in the red kangaroo. As with other anoestrous females, lactating ones bred also and so regained the reserve blastocyst usual to regular lactating females. In these ways, a large proportion of female kangaroos circumvented the deleterious effects of drought upon recruitment into the population – a remarkable adaptation of a mammal to a drought-ridden environment.

Male reproduction Under gentle conditions in captivity, male red kangaroos remain in breeding condition continuously. But one curious feature readily evident in the fieldwork described above was that few females fell pregnant immediately after drought-breaking rains, despite coming into oestrus. Most pregnancies came at the following oestrus five weeks later. That Mother Nature, so clever in other

59

4: Reproduction

respects (as outlined above), should arrange matters as to ‘waste’ breeding potential was hard to understand. I later discovered that the fault lay with the males. Though my initial analysis of the microscopic structure of testes showed sperm production in all males, more detailed analysis 10 years later revealed a defect in sperm production. Some tubules could be found with sperm, but detailed counts of the presence or absence of the cells usual to the germinal layer, spermatogonia,33 spermatocytes,34 spermatids35 and spermatozoa,36 presented a different pattern (Table 4.1). In hot weather, the two outer layers of cells, the results of meiotic division, were often missing. Some animals even lacked spermatocytes. Their tubules contained only a basal layer of spermatogonia plus elongate Sertoli cells37 arranged Table 4.1. weather.

Reduced sperm production in male red kangaroos during hot

Data are from Newsome (1973).

Cell types usually present

Cool weather Mean no. of tubules with cells (n = 10)

No. of males with cells (n = 10)

Spermatogonia

10

Spermatocytes

10

Spermatids

9.6

Spermatozoa

3.8

No. of cells in spermatogenic layer (±standard error)

4.8 ± 0.2

Hot weather Mean no. of tubules with cells (n = 10)

No. of males with cells (n = 10)

10

10

10

10

6.9

10

10

6.9

9

9

0.7

3 3.2 ± 0.3

60

The Red Kangaroo in Central Australia

a

b

Figure 4.5: (a) Sections through an impaired testes of a red kangaroo during hot weather as indicated by the absence of cells (compare with (b)) usual to the spermatogenic layers of males. (b) Sections through testes of a red kangaroo during cool winter weather. No signs of impairment were apparent as indicated by the presence of cells (compare with (a)) usual to the spermatogenic layers of males. Figures are from Newsome (1973) .

like cartwheels (Fig. 4.5a). In healthy tubules, the elongate Sertoli cells nourish mature sperm, but are hard to see microscopically because other cells distort their shape (Fig. 4.5b). Extreme heat is known to sterilise Merino rams temporarily (Gunn 1942). Heat impairs the formation of a spindle in dividing cells so that multi-nucleate cells appear and the vasa efferentia38 that normally carry sperm away from the testis are laden with cellular detritus and no sperm. Such features of inanition were found in some of the red kangaroos also. And, when the proportion of adult males (three years) displaying impaired spermatogenesis in any sample was plotted against the number of preceding days in which the air temperature had exceeded 32°C, the usual temperature of a kangaroo’s scrotum, there was a positive response (Fig. 4.6). The conclusion therefore was that the hot summer of Central Australia sterilised an increasing

61

4: Reproduction

number of males as it progressed (Fig. 4.7). This was the first report of heat sterilisation of a marsupial.

Impaired spermatogenesis

1

0.8

0.6

0.4

0.2

0 0

50

100

150

Hot days (>32ºC)

Figure 4.6: The proportion of red kangaroos with impaired spermatogenesis related to the number of summer days when maximum ambient temperatures exceed 32°C. Data are from Newsome (1973).

Proportion with interstitium reduced

1

0.8

0.6

0.4

0.2

0 0

2

4

6

8

Drought index

Figure 4.7: The proportion of red kangaroos with reduced interstitium related to the severity of drought. Data are from Newsome (1973) .

62

The Red Kangaroo in Central Australia

One other change noticed while microscopically examining the testes was that there seemed to be fewer and smaller interstitial cells between tubules in red kangaroos during drought than after good rains. Counts of cells on a special microscope showed this to be so. Moreover, interstitium comprised only 1.6% of the testes during the drought but 6.9% later. Sexual drive in some males may be diminished therefore during drought since interstitial cells produce male sex hormone(s). So, hot droughty weather impaired sexual function in males as well as females. Since red kangaroos are polygamous,39 it may be that the odd one or two potent males can fertilise all receptive females in a population. This, however, does not seem to be so. Careful search among females shot during oestrous cycles revealed proportions in some samples that had not been fertilised. The proportion that had been fertilised (i.e. they were pregnant) was then plotted against the respective proportions of potent males in the sample. The result was surprising, for it seems that Mother Nature does indeed permit receptive red kangaroo females to go unmated in Central Australia. No more than 70% of females became pregnant (Fig. 4.8). Since it takes about six weeks of cool weather to repair heat-damaged testes, here, then, was the explanation for the number of unmated females immediately after drought-breaking rains. This defect seems rather curiously anomalous alongside complex reproductive adaptations of females. While poorly nutritioned during drought they continued to produce young, yet, despite abundant green

4: Reproduction

63

Pregnant females (%)

80

60

40

20

0

0

20

40

60

80

100

Potent males (%)

Figure 4.8: The relationship between the proportions of pregnant female and potent male red kangaroos. Data are from Newsome (1973) .

grass after rains, 30% of them failed to mate. The fault clearly lay with the males. It may be that the red kangaroo is near the northerly extreme of its range of heat tolerance in Central Australia. I doubt this, however, because red kangaroos do live 500 km further north. Moreover, kangaroos are seen near watering points rather rarely in Central Australia. Body temperature in the red kangaroo is labile, rising to ~39°C on a hot day and falling again at night (Dawson & Hulbert 1970), just as in the camel. The male licks its scrotum in hot weather, presumably keeping the temperature down. If the male is exposed to prolonged excessive heat, however, it seems as if it is unable to regulate scrotal temperature adequately. It will be explained later (Chapter 7) that the kangaroo’s current use of habitat in Central Australia is

64

The Red Kangaroo in Central Australia

most unlikely to be the ancestral mode. Red kangaroos have most probably expanded their use of open plains due to changes in the food supply created by cattle grazing. It seems, however, that the kangaroo has had to pay a price for the increased usage of open plains, lack of adequate shelter having resulted in impairment of male reproduction and therefore, in reduced pregnancy rates. Presumably, the price is worth it in terms of increased food supply that may allow breeders to live longer and produce young further into a drought than before. There are, then, many processes involved in successful reproduction of red kangaroos. One gripping question is the evolution of the mechanism prolonging pregnancy during a long lactation. The mechanism may not have evolved in the red kangaroo in the present arid climate with its landscape and vegetation. One very good reason for thinking this is that the mechanism is common to a large number of macropodids living in various other places in Australia and New Guinea, from cool temperate areas and the wet mild subtropics, to the monsoonal tropics. Since these macropods are closely related, it seems most likely that the mechanism evolved in an ancestral kangaroo, but nevertheless in a vicarious environment. Reproduction in the red kangaroo is neither seasonal nor a stop and start system triggered by rain, as found in arid-zone birds. Rather, it is opportunistically dependent on the supply of green herbage. Kangaroos will breed all year round in good times. During drought, breeding gradually loses impetus, various adaptations keeping the process in the population going for a long time into

4: Reproduction

65

drought through a cyclic series of births and deaths of young. Since droughts must be finite, some must survive. These survivors would have a running start when it rains again. This system may seem wasteful, but it has the advantage that the mother does not lose her life. It costs relatively little energy, in an evolutionary sense, for such a large animal to be pregnant for only five weeks, to give birth to a young less than 1 g in weight, and then to suckle it for about two months to a weight of ~60–70 g. The mother could weigh up to 25 kg. So the mother survives the drought to breed successfully again. The red kangaroo’s method of breeding is, in fact, a good investment for so harsh and capricious an environment where there is no guarantee of rain. By contrast, the introduced cattle are not so fortunate. Its breeding biology often destroys the mother. Like the kangaroo, cattle also need green grass to breed; but pregnancy lasts nine months and calves at birth are large. The weather can change for the worse in nine months. I have, in fact, seen cows calving in the middle of a drought and heat wave with ambient temperatures exceeding 50°C. The mothers were skin and bone and the calves fit and well, i.e. until the mothers finally collapsed. Then the calves die. Thus, domestic stock are greatly wasteful of the vegetation of the arid zone. The red kangaroo’s biology is more closely tuned to the environment.

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5 Food and water

We have come to expect large desert animals to be hardy, like the camel or the Arabian oryx (Oryx leucoryx). Animals have solved the problems of survival in deserts, however, in many ways. This is one of the biological fascinations of deserts because there are always surprises. Some species solve the problems simply – they leave in bad seasons. The diamond dove (Geopelia cuneata) and the budgerigar occur in amazingly large flocks numbering thousands in good seasons (Plate 7), but cannot be found at all during drought. Mammals are not so mobile. One of them, seen commonly during good seasons, sometimes in plagues, is the spinifex hopping mouse (Notomys alexis). For it, the solution to dry seasons lies in an ability to concentrate its urine. The hopping mouse is so successful

68

The Red Kangaroo in Central Australia

that the small amount of water in the apparently dry seeds eaten suffices for its needs (MacMillen & Lee 1967). Most desert species lie somewhere between these extremes of adaptation. Some are water dependent, some partially nomadic, some burrow and most are nocturnal. Nothing was known of the red kangaroo’s water physiology and reports were conflicting. Greatest numbers were reported on the best pastures and yet some lived in the spinifex deserts, the harshest of land. They often drank at some dams, but hardly at all at others. In fact, Aboriginal mythology relates that the red kangaroo obtained water by magical means (Strehlow 1968) (Chapter 7). Its aunt, the mulga parrot (Psephotus varius), fetched water long distances to them by night in special hide-bags made of kangaroo skins. Animals acquire water from their food as well as from drinking, sometimes enough to go without drinking. An extreme example is Notomys already mentioned. Parakeelya (Calandrinia balonensis) is a small fleshyleafed plant, which sometimes carpets the desert with its purple flowers after rain. Its moisture content is very high, and cattlemen say that their stock do not need to drink when eating it. This can create a problem especially on those runs bordering the Simpson Desert. Stock will keep nosing into the south-easterly wind grazing further and further away, even when continually turned back by stockmen. So, to this extent, an animal’s diet and water needs may be linked. There are other linkages described later in this chapter e.g. metabolic water and protein content of the food. It is appropriate here, however, to discuss diet alone.

5 : Food and water

69

Food A study of the diet of the red kangaroo was conducted by Mr G. Chippendale (Chippendale 1968b), the first resident botanist in Central Australia. For comparison, he also studied the diet of cattle with which the kangaroos were thought to compete (Chippendale 1968a). At the time, methods of identifying the finely ground stomach contents of red kangaroos were exploratory. Knowing the Central Australian flora as well as he did, Chippendale chose to take ~20% of the stomach contents of any kangaroo shot, wash it through a fine sieve, dry the sample in the sun, and then painstakingly pick over the remainder and identify the fragments. If a fragment confounded him, he returned to the place where the kangaroo was shot and searched until a matching living plant was identified. It was his skill as a taxonomist that allowed Chippendale to take this direct approach. Other techniques used in Western Australia and Canberra depended on microscopic examination of quite small samples of faeces or ingesta. In the latter case, plant material was finely ground and sieved to provide microscopic but relatively uniform particles. Though grinding finer than the kangaroos may seem counterproductive, it had been found that many plants possessed cells of unique shapes or with crystalline inclusions. For example, cells from the leaf surface of Aristida have fine hairs, while Eragrostis, another grass, had dumb-bell shaped inclusions. Given such a code, the beauty of finely grinding the material of every species to equal size was that individual fragments needed only to be tallied in order to accurately assess the composition of the diet.

70

The Red Kangaroo in Central Australia

In a preliminary study, Chippendale first shot kangaroos from widely separated parts of Central Australia for clues to the extent of the kangaroo’s diet. His analysis indicated that they ate around 70 plant species (cattle ate almost three times that number). Eleven species eaten by kangaroos were grasses, there were eight species of trees and shrubs and the rest were forbs, a general term for herbaceous dicotyledons. An intensive study of the diet of the red kangaroo then began on the Burt Plain already identified by the aerial surveys as an important drought-refuge for the kangaroo (Chapter 3). The diets of 189 kangaroos were examined over a two-year period from October 1959. To identify every particle in the stomachs of a large number of kangaroos was too painstaking. So Chippendale used an unbiased method of selecting from two to four samples of 100 fragments each from every stomach. Tests showed that only the rare items in samples might be missed or their abundance underestimated. Some quite small grass fragments were impossible to identify also. Overall, ~40 species of plants were eaten, but two results stood out. The stomach contents were invariably green, even in drought, and grass, especially neverfail, was overwhelmingly predominant. The overall contribution of the various plants to the diet of the red kangaroo are compared for good seasons and bad in Table 5.1. The seasons also made a difference. After rains, when herbage flourished, 98% of the diet was grass, over half of it being perennial species uncommon during drought. The ubiquity of green feed at such times allowed the kangaroos to scatter into the mulga

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Table 5.1. Diet of the red kangaroo in Central Australia. Calculated from Chippendale (1968b).

Plants

Good seasons (%)

Drought (%)

Kangaroos eating on the plains (%)

Grasses Eragrostis setifolia

24

54

81

Other perennials

56

22

88

Annuals

18

14

83

Trace only

5

28

1

3

87

Trace only

2

62

Forbs Perennial Annual Trees

woodlands in particular (Chapter 3). It also permitted a broader selection of foods. For example, in May 1961, in a good season, only 31% of the diet was perennial grass (five species), with 68% annual grass (six species). In February that year, during drought, the relevant statistics were 92% perennial (five species) and 3% annual (three species). The utilisation of forbs tended to be the opposite; but be warned about percentages. If one item increases, others must decrease. The results presented are relative not absolute. For example, if kangaroos ate more food in good times than in bad, and you can bet that they did, then they may well have eaten more perennial grass by weight than in drought though relatively they ate less. During drought the kangaroos concentrated around the open plains (Chapter 3). The reason was easy to see

72

The Red Kangaroo in Central Australia

for the simple reason that there was green feed there. And the most abundant green feed was in the gilgais even though in reality it was only a sparse green mat of neverfail. At the height of the drought, kangaroos stood side-by-side clustered around gilgais feeding. The whole plain within view of the spotlight was dotted with their clusters. The greatest assemblage of kangaroos seen like this numbered over 500. Small wonder, then, that neverfail transpired to be the favourite food. Chippendale measured the abundance of neverfail, among other plants, in two gilgais partially fenced in to exclude cattle and kangaroos. Two to three times more herbage grew inside the fence protected from grazing than outside. Half was neverfail inside the fence but, interestingly, the proportion was 60% outside. This indicates that this species may perhaps withstand grazing better than other inhabitants of the gilgais, which were mostly forbs. By and large, forbs do have a higher protein content than grasses, so it would not be surprising if they were preferentially grazed by cattle or kangaroos. But, as neverfail remained green during drought and was virtually the only herbage present on the otherwise bare plain, it provided the only protein to kangaroos then. If kangaroos ate more mulga, like cattle, this would not be so. In fact, the quantity of top-feed eaten by kangaroos is minimal despite its abundance. Sometimes after rain, vegetation of another kind can be abundant also without being eaten. At first glance, this might seem surprising because the species are grasses, and often mostly neverfail. After rain, when herbage of all kinds abounds, the clumps of perennial grass are able to

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grow, mature and seed. Once seeded, they die off leaving an abundance of tall dry grass. Kangaroos are sometimes seen grazing among this tall dry grass; but on close examination, they are found to be eating either green forbs growing between the clumps or small green shoots growing out from the base of the clumps. Hence, they do not eat the abundant dry grass. Kangaroos do fare badly on dry feed low in protein (McIntosh 1966). Indeed, there is so little protein in dry chaff (protective casings of seeds) that animals have to mobilise their own protein for essential processes. It is most likely for this reason that female reproduction is restricted during drought, as detailed in Chapter 4. It remains, then, that the essence of survival for red kangaroos in Central Australia is the availability of green herbage. Since droughts are the real test of survival, the availability of one species of grass, neverfail, holds the key. Male red kangaroos grow to a much greater size than females (Chapter 6). Moreover, data based on the samples of kangaroos shot contained a surprise: females always outnumbered males about three to one. These facts led me to wonder if the two sexes ate different plants. Chippendale’s data were suitable for this investigation, the first 200 stomach material fragments from each of his 189 animals being utilised. Because summer rains promote growth of grasses and winter rains promote forbs, the data were divided accordingly. Then, each set was subdivided again into three periods: when pastures were green after rain, when they were drying up, and drought.

74

The Red Kangaroo in Central Australia

The results once more emphasised the value of grass to the kangaroo. For example, ~99% of the diet of both male and female was grass immediately after rain fell, regardless of the season. One reason is that grasses always sprout and grow rapidly after rain, and another is that its prevalence allows kangaroos free choice. The results also highlighted some differences, however, even though they may not seem great. For example, progressively more forbs were eaten as time passed after winter rain than during summer, over 10% compared with less than 5% respectively. But the difference we were looking for, between sexes, was also revealed (Table 5.2). During drought following winter rain, 21% of the diet of males is forbs with 9% among females. Both sexes ate more trees at that time than at any other even though the fraction of the diet was small, 2–3%. Perhaps, though, the high intake of forbs and trees, ~16% overall, indicates a shortage of grass at that time. Now, one problem with these results is that partitioning the overall data on diet on 189 kangaroos into 12 classes reduced sample sizes. It is possible then that results could just be an accident, depending on the precise locality where kangaroos fed before being shot. It is possible that, by chance, there just could have been more forbs there. This notion of accident received support when the actual species of plant eaten were examined. The increase in forbs was due to the increase of just one species of plant, the white paper daisy, which becomes abundant in places after winter rain. But, the results could also indicate that males and females tended to choose slightly different plants to eat or tended to live in slightly different parts of the Burt Plain.

Totals

Drought

Drying pastures

Green pastures

94

96

Males

96

Males

Females

93

95

Males

Females

94

99

Males

Females

98

4

5

3

5

5

6

Trace

2

Trace

1

1

2

Trace

Trace

Trace

Trace

89

89

77

88

89

83

99

99

10

10

21

9

11

16

Trace

Trace

Forbs

Grass

Trees

Grass

Forbs

After winter rain

After summer rain

Females

Data are from Newsome (1980).

Table 5.2. Seasonal diet of the sexes of red kangaroos (%).

1

1

2

3

Trace

Trace

Trace

Trace

Trees

Yes

No

No

Differences between sexes (summer)

Yes

No

No

Differences between sexes (winter)

5 : Food and water

75

76

The Red Kangaroo in Central Australia

Occasionally we used to come upon groups of large adult males camped apart. This experience used to surprise and even perplex us as we expected always to see females and males mixed about three to one. It does seem possible, then, that male and female red kangaroos may live slightly different lives (apart from their primary sexual roles of course). To the extent that diets are different, more kangaroos can survive on the one area in a time of shortage. And, if there is more food for females because males eat some other plants, then the reproductive rate would be so much better and the survival of young also. There is, then, a very real adaptive reason for expecting male and female kangaroos to evolve such differences. It is useful at this stage to comment on the diet of the only other kangaroo of the arid zone, the euro or hill kangaroo. As its alternative name implies, the euro inhabits the rocky hills and ranges in contrast to the red kangaroo. It is not all that common in Central Australia but abundant in north-western Australia in the region around Marble Bar and towards the coast (Fig. 1.3). It is regarded as a pest to the sheep industry there and has been intensively studied by Tim Ealey (e.g. Ealey 1967a, b, c; Ealey & Main 1967). The trouble in the north-west was that sheep grazing and the availability of artificial watering points greatly enhanced the landscape to favour the euro. The increased availability of water meant that euros were no longer restricted to sheltered habitats in the hills. Euros could survive out in the unsheltered open. But, as euro numbers increased, the combined effect of grazing by both the

77

5 : Food and water

introduced flocks of sheep and the artificially increased number of euros led to overgrazing of the nutritious grasses. As the less nutritious spinifex took over, particularly on scythed land, the euro could easily outcompete sheep because they could manage to survive better on this hard spinifex diet. While this outcome confirmed the suspicion of pastoralists implicating the euro in the demise of the sheep industry, it was a more nuanced explanation than what had originally been suspected. The increase in euro numbers in the north-west was directly attributable to habitat alterations by humans. The red kangaroo also inhabits the region and so the diets of all three herbivores, the two native kangaroos and the introduced sheep, were studied in infertile dry parts of the inland as well as near the coast. It is sufficient at this stage to relate that the euro is able to survive and breed on a diet of almost completely pure spinifex very low in protein (Table 5.3). The red kangaroo, however, cannot do so. With euros living mainly in the hills and the red kangaroo mainly on the plains, and each with Table 5.3. Diet of euro and red kangaroo in north-west Australia during drought (%). Coastal pastures

Euro

Less fertile pastures further inland Red kangaroo

Euro

Spinifex

19

12

67

More nutritious grasses

72

73

26

Forbs and shrubs

9

15

7

78

The Red Kangaroo in Central Australia

different minimum requirements for nitrogen, the two species may not compete much for food. But, with increases in the availability of spinifex in north-western Australia (noted above), it probably reduced the separation in diets between the two species, and the red kangaroo subsequently became rare.

Water Water comprises 99% of all molecules in a living animal (Macfarlane & Howard 1972). It is the vital medium within which all the chemical reactions for life proceed. Deserts place the greatest heat loads upon life. To give some idea of just how great, the radiant energy falling on just one hectare (2.5 acres) of ground in Central Australia on a summer day is supposedly the equivalent of that released by the atom bomb dropped over Hiroshima. Admittedly, the comparison is a bit of a trick since the sun’s radiation is summed for a day. Nevertheless, no exposed animal can withstand such heat. A man without water or protection would die of dehydration in a day, two at the outside. How, therefore, does the red kangaroo manage? Like all animals, water balance in the red kangaroo is the result of profit, loss and prevention. Water is drunk, or ingested with the food, lost through urine, faeces, sweating and panting, and saved through special behavioural and physiological devices. To the extent that urine and faeces can be concentrated and the need for evaporative cooling prevented, an animal does not need to drink. Similarly, to the extent that its food is lush, the

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animal needs to drink less water. Green food, however, can be high in protein, and after metabolism, the waste product from protein, urea (uric acid in birds and reptiles), must be excreted. Since urea is a toxin, it must be kept dilute until it passes through the filters in the kidneys. Then, water is reclaimed from the urine as it passes down convoluted tubules in the kidney to the ureters. A dehydrated animal withdraws more water back to its tissues than otherwise. This facultative process is under the control of an anti-diuretic hormone called oxytocin released by the posterior pituitary. Red kangaroos drink sufficiently frequently elsewhere in Australia, in New South Wales and Western Australia, for example. By contrast, kangaroos in Central Australia appear to be relatively free of the need for drinking water and can be found in utterly waterless country. A remarkable old gentleman named Joe Jackson was the last of the professional kangaroo shooters around Alice Springs during our study. He used also to shoot on Eva Downs and in South Australia at times. Shooters there had merely to wait at water for the kangaroos to come in. A man would go broke around Alice Springs trying that ploy. You have to go and look for them. Kangaroos are seen drinking sometimes in Central Australia. My offsider, Dean Stephens, an exceptionally able man, watched the kangaroos near a bore north-west of Alice Springs right through the night once. It was during drought. The animals slowly grazed their way in to the water to drink, and then slowly grazed their way back out again. At some stock waters, it is not the water which interests them so much as the green grass (usually couch

80

The Red Kangaroo in Central Australia

grass, Cynodon dactylon) growing on seepage or at overflows. Storr (1968) noted this same relationship in north-west Australia. Some waters always had a few dead kangaroos around. It was folklore that these animals had come to the bore perishing but drank too much too quickly and had died. Understanding of water physiology of the red kangaroo is sketchy and the picture had to be pieced together. Even so, the facts are quite remarkable, and demonstrate that the red kangaroo has its share of desert adaptations. The first thing, of course, is that red kangaroos do not stand out in the midday sun. They choose a shady tree for lying up during the day, and will shift with the shade as the sun moves. Before reclining, kangaroos often dig a hip-hole (Plate 15) so that trees are often ringed with holes at the end of the day. The holes may be merely for comfort, but contact with cool earth may help unload heat also (see below). The shade cast by a spindly limbed, thin leafed mulga tree looks sparse and totally inadequate. Try it yourself on a hot day and you will soon seek something leafier like a gum tree. However, such shade actually cuts the radiation from the sun by an astonishing 80% (Dawson & Denny 1969a). Whenever an animal is disturbed on a hot day, it reluctantly rises and slowly hops to the next shady tree. It knows where it is well off. The heat load in the shade may still exceed the animal’s temperature by as much as 30°C at midday. In late afternoon, the micro-environment may cool down below body temperature, 35.5°C. The animal then loses heat to its environment.

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One facility some desert animals have is to allow their body temperature to rise during the day without sweating or panting to prevent it. The camel is the best performer, its body temperature rising as much as 5°C (Schmidt-Nielsen et al. 1957). The Arabian oryx and Grant’s gazelle (Nanger granti) are similar (Taylor 1970). The red kangaroo has a lesser ability and body temperature rises only ~2°C before commencing to pant. Man, of course, starts sweating after less than 1°C rise in temperature, so crucial is it to retain an even temperature. The advantage to the red kangaroo, of course, is that heat accumulated by day is simply unloaded in the cool of evening. Water, which would otherwise be evaporated to keep cool, is saved. The density of the red kangaroo’s fur insulates it from heat better than the thinner coat of the hill kangaroo (Dawson & Brown 1970), but no better than tropical placentals. The reflectance of the fur is higher also than for the hill kangaroo (Dawson & Brown 1970), reflecting 15% more heat from the hip. Generally speaking, the paler the fur on the red kangaroos, the better. For example, the hip reflects 33–58% of radiation compared with 27–28% on the back. Hair on the red kangaroo’s hip is thinner than elsewhere, however, so that penetrance of heat may be greater. Perhaps one of the reasons why kangaroos dig hip-holes when they lie down is the cool earth will conduct some of the heat away. In southern Australia, female red kangaroos are mostly blue in colour. Males are mostly red. Between 15–20% of both sexes are a mixed red-blue colour. In western New South Wales there were 68% blue and 12%

82

The Red Kangaroo in Central Australia

red coats on females (Dawson & Brown 1970). In Central Australia, the figures are virtually reversed at 24% and 63% respectively. The differences in the above coat colours indicate that there may be a genetic basis for the distinction. The proportion of blue animals also changes cyclically with the season. In mid-summer, 75% of females were ‘male’ coloured, 1% were blue and the rest a mixture. In mid-winter, on the other hand, the proportion of ‘male’ coloured females dropped to 50%, the ‘blue fliers’ having increased to 20%, with 30% a mixture. Even females of mixed colours show the same cycle. More of them are predominantly blue in winter and more predominantly red in summer. Red fur reflects ~25% more solar radiation than blue. Since over 50% of that radiation is in the red end of the spectrum and into the infrared (i.e. the hottest end), it is an advantage for females also to be red in summer. Being paler than the male, they probably reflect more heat, which may compensate for their smaller size. Small animals have a larger ratio of surface area for their body size and therefore take in relatively more heat. In the winter, being blue may equally help the females to warm up on cold days. Kangaroos always sun themselves then, taking shelter only from the wind. The problem about being a good colour for absorbing heat is that colour is a good radiator as well. Females may therefore feel the cold more than males. Because of their mode of reproduction, marsupials were once thought of as second-class mammals. Mammals of the lowest class were of course, the platypus (Ornithorhynchus anatinus) and echidna (Tachyglossus aculeatus) because they lay eggs. Naturally, therefore, the

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European view was that their familiar placentals were of the highest class. Alas for the placentals, marsupials in general are now known to possess an inherently lower metabolic rate than placentals (Dawson & Hulbert 1970). What this means to a marsupial is that it can live on ~30% less food than placentals, and produce, accordingly, less heat in the process. These properties provide marsupials with an advantage in any environment, but especially in deserts where shortages of food and excesses of heat are a common problem. The red kangaroo’s fur is almost ideally suited to reflect and insulate it from heat, and the animal itself produces little heat (one calorie/gram/hour) to dissipate. In those ways the kangaroo avoids the need to use water for cooling. Nevertheless, when temperatures are high for long periods each day, over 40°C say, red kangaroos pant. They also salivate freely and dribble it over their arms, legs and scrotum in the male, though this is an inefficient cooling mechanism (Dawson et al. 1969), because water so lost must be regained. Four tame kangaroos kept partly shaded at Alice Springs were studied to measure the water used in hot weather. Maximum air temperatures ranged from 41– 43°C during the two-week study. Individual water use each day ranged from 1.3 to 2.9 L. When differences in size of the animals (14.5 to 32.7 kg) was allowed for, the usage per day was remarkably constant, 88 mL/kg, representing an average of 11.5% of body water per day. Comparisons with other large animals in the same environment show that the kangaroo’s need for water each day is quite sparing (Macfarlane et al. 1963). Only

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The Red Kangaroo in Central Australia

the camel is more conservative, needing ~75% of the kangaroo’s rate. Merino sheep need 25% more, weight for weight, and short-horn cattle are like sieves, needing almost double the amount per kilogram. When water use is expressed in terms of metabolic rate, however, the kangaroo’s usage was the most conservative, and must be even more so since its resting metabolism is ~30% less than placentals and its body temperature 2 to 3°C less (Dawson & Hulbert 1970). What this means to a resting red kangaroo at Alice Springs is that it needs 1 to 3 L of water per day in summer, about half their bodyweight in five days. Green grass in the diet of wild kangaroos contains ~25% water (Chippendale 1968a,b). To obtain all its water from food, a red kangaroo would need to eat ~30% of its bodyweight in tucker a day. As this exceeds its food requirements, the wild kangaroos must drink sometimes. Water needs in the wild require more study, but the use of tritium, a mildly radioactive form of water injected into animals captured, released and recaptured again later, do indicate that the red kangaroo uses less water than sheep or even the hardy feral goat (Denny & Dawson 1975). Wild kangaroos utilise their ability to concentrate urine to conserve water. Sodium was eight times more concentrated in the urine during drought though its content in blood remained unchanged. Urea was almost twice as concentrated. The urea concentration was about half that found in western New South Wales (Dawson & Denny 1969b) perhaps because the protein content of the food was lower, but electrolyte concentrations were over 20% higher. The maximum sodium and potassium

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concentrations found near Alice Springs were 800 and 5200 mg/L respectively. These values are considerably higher than those found in the milder environment of western New South Wales (Dawson & Denny 1969b). The wild kangaroos sampled near Alice Springs were usually within 3 to 4 km of water and had easy access to it. They could have drunk if they wanted to. The same situation existed in western New South Wales (Dawson & Denny 1969b). The hill kangaroo, which intrinsically appears to be better able to concentrate its urine, has more dilute urine than the red kangaroo. The hill kangaroos live conveniently close to water and presumably drink often. The red kangaroo lives further away, just as at Alice Springs. Presumably, as mentioned previously, the animals avoid the need to drink frequently by eating green grass, making good use of shady trees and concentrating the urine. By similar techniques, two antelopes of East Africa, the topi (Damaliscus korrigum) and eland (Taurotragus oryx), can manage without drinking at all (Vesey-FitzGerald 1960). Despite their abilities, some red kangaroos do perish. Numbers of dead ones were seen in the desert proper during our aerial surveys (Newsome 1965b; Newsome et al. 1967). And, a colleague and I found a dead kangaroo in the Simpson Desert during a severe heatwave. Temperatures in the shade exceeded 50°C every day for a week and a fiercely hot strong southeasterly blew constantly. The kangaroo was emaciated and very light for its size. Its stomach contents were straw-like and almost dry to touch. The most striking feature was that the skin on muzzle, arms and lower lip had dried out

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The Red Kangaroo in Central Australia

and was stiff and shrunken like parchment. Yet, the animal was quite fresh, with stomach unbloated and no signs of decomposition. Though the kangaroo had survived a quite high degree of dehydration, it finally succumbed.

6 Sociology

Man grows up expecting animals to have structured societies. Man has the family as his basis. Families may band together into clans, or larger communities. From these simple units, villages, cities and nations arise. We notice how many animals function similarly at the simple level. Ants and termites live in giant communities with caste systems providing division of labour. Wolves (Canis spp.) maintain permanent family groups and defend territories to ensure an adequacy of resources. To come upon a species whose society appears to lack even the simplest of familiar structures is therefore a surprise. The one sure bond in red kangaroos, and perhaps the only one, exists between mother and young. Yet, even that bond is expendable. With feed scarce during drought,

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The Red Kangaroo in Central Australia

the mother does not behave anthropomorphically, disadvantaging herself for the sake of the young. To the contrary, the young is expendable and perishes early. This adaptation ensures the mother’s wellbeing and survival (Chapter 4). The only other bond witnessed, that between a buck and a doe on heat, is highly tenuous, lasting for so long as courtship and mating requires. The buck may have to fend off other contenders, but the whole process appears to be opportunistic and promiscuous without a sign of formation of a family group, let alone harems. Ecologists have come to realise that social systems are exploitative systems, allowing better use of resources than otherwise. For example, a lone dingo (Canis dingo) can kill a possum, bandicoot or rabbit, but a pack can kill a kangaroo and gain far more flesh per dingo than otherwise. So the question arises for the red kangaroo: how can the lack of any strong social system be an advantage? Below I outline some possible reasons.

Group size During the five years of our study on red kangaroos, sizes of groups were counted. In good seasons, a total of 2589 kangaroos were counted in groups of varying sizes of up to 10 animals. In drought, 4311 kangaroos were seen and the largest group contained 18 animals. Groups were larger on average during drought. For example, 27% of kangaroos were alone during drought, with 38% of them in pairs. In good seasons these proportions increased to 31% and 45% respectively. By comparison, less than 1% of red

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kangaroos were by themselves in central New South Wales (Frith 1964) indicating, perhaps, quite high densities, though counting techniques differed. The precise structure of groups is unknown. Our observation was that the presence or absence of any particular kind of animal, e.g. a large buck, could not be guaranteed. There was no semblance of family groupings. Groups seemed to assemble and dispense with great facility and no particular cause. On three consecutive afternoons, I sat and watched the kangaroos emerge from the same patch of scrub on the Burt Plain. There was no pattern. No particular animal emerged first, whether old man, doe, or young. No particular grouping emerged first or last. Numbers differed on the three days. Though there was an abundance of feed around, kangaroos seemed to find distant pastures greenest. An animal would no sooner emerge and look around, perhaps eat a bit or scratch at itself or the ground than it was off over the horizon. There seemed to be no particular reason, just a native restlessness. Overall, our sampling indicated that grouping in red kangaroos is a random process of animals joining and leaving, just as suggested for western New South Wales (Caughley 1964). Thus, if kangaroos are abundant, then larger groups should arise. With further increase in abundance, groups should coalesce to form mobs. Mob formation in turn would create a patchy distribution of kangaroos. Large mobs are seen, and perhaps are only possible, during droughts when kangaroos are concentrated around the open plains and often droughtrefuges for food. I have seen several small mobs of 20 to

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The Red Kangaroo in Central Australia

30 animals in my time, and five large mobs, all during drought and all on drought-refuges. Three of the large mobs numbered 100 or so, another 150, yet another of 540 or so, with the largest group ~1500 strong. When disturbed, the kangaroos behaved as a group, all moving in the same direction, follow-the-leader. Usually, the mob leisurely cuts across the path of the observer in his car. One persistent folklore about kangaroos in Central Australia is that they always move to the south-east, i.e. into the prevailing wind. This direction also leads to the Simpson Desert, which makes no sense. However, most roads in Central Australia are either north–south or east–west. And when the observer was asked what direction he was travelling, it transpired that he was heading in such a direction that would lead kangaroos to travel across his line of travel – south-east. The mob of 1500 odd kangaroos mentioned in earlier chapters needs greater mention. Kangaroos had been reported abundant on the Quarantine Paddock just south of Alice Springs along the banks of the Templebar Creek. So one hot day I went over to see. The scene was unbelievable. Under every shady tree there were kangaroos. At my approach, they stood up, alert, spun around and headed off in such hordes that it was impossible to count them directly. Of course I tried, but the kangaroos were disappearing into the scrub faster than I could count. I tried counting in tens and was still losing the battle until I found that the four fingers of the outstretched hand covered ~100 beasts. It took 15 shifts of my hand moving through an arc of almost 180 degrees to encompass that mob. It was a huge mob, and, though my technique of

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estimation was crude, nothing less would have come anywhere near the mark. There is, then, a tendency for red kangaroos to be gregarious, to respond to others by approaching, staying near and perhaps sniffing them. Kangaroos may sniff others’ noses, mouths, pouches or genital regions, the latter especially when a male is courting a female on heat. Grooming is a most social function and regarded as a means of reducing tension within a group (Russell 1974). Kangaroos rarely groom. Not uncommonly, the reaction to the near approach of another is for the animal to cuff at the intruder into its personal space. Large animals will often displace a smaller, e.g. from beneath a shady tree. Sometimes it is accomplished by bluff; but one animal may grab the other around the middle pushing it away, making one of the kangaroo’s rare noises at the same time. It sounds like ‘Ha’ (Russell 1970). Kangaroos possess intimidating threat displays. The kangaroo stands tip-toe, balancing on the tip of the tail as well. In this way they stand well over six feet (1.8 m) tall. The ears stand straight up, and, with the chest puffed out and shoulders back, the animal may bite and slobber on its fore-limbs. The penis may be extruded, squirting small spurts of urine. Real, stand-up fights, however, are rare. Mostly they are witnessed in captivity. On tip-toe and tail again, the antagonists hop stiffly at one another from close range and grapple with the forearms, heads thrown well back. If one gains a purchase with the hands, then, quick as a flash, the feet come up to strike at the belly. Disembowelling is entirely possible though I have never seen it.

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The Red Kangaroo in Central Australia

The most vicious fight I have witnessed was between two old man hill kangaroos caught in a trap-yard in northwest Australia. The two were hopping slowly in opposite directions around the fence. Neither gave way on approach but merely fell on the other. One caught the other in a headlock, teeth could be heard meeting through the luckless victim’s ear. The victim, meanwhile, supported itself entirely on its tail, ripping at the other’s gut. The two warriors remained locked together in this way for about a minute. Except for the crunching of the teeth, the whole fight was conducted in eerie silence. Then, they simply parted, and continued their rounds with no other signs of animosity. So far, we have concentrated on rather straightforward sociological elements, like family groupings, mob formation, fighting, etc. But, sometimes there are indirect clues full of surprises. It was always a puzzle how few male kangaroos were collected in our samples. Time after time we shot roughly three females for every male despite strict precautions against bias. The trap to avoid was shooting the nearest or the largest kangaroos. Our system for unbiased selection was explained in Chapter 4, and it cannot be stressed just how important the selection procedure is to my argument here. We have absolutely no evidence that any bias entered into our selection. At no time did we detect kangaroos of a particular kind, say, the largest, or the smallest, escaping before any others. It is possible that some sneaked away at the sound of our vehicle before our spotlights picked them up. But we never saw particular kangaroos by day or night hop away early if the vehicle was being driven slowly and

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no sharp noise, rattle or clank was made. They just stood their ground or moved away as a group. Where kangaroos are shot at frequently, they certainly do get nervous. Only one other shooter besides ourselves was operating regularly on the 4000 km2 of our study-area, however, so that there was plenty of room for a few folk from Alice Springs who drove out for some ‘sport’ occasionally. As mentioned previously, the only time kangaroos were scarce was after rain, and this forced us to fire upon all animals seen. However, there were still three females for every male in such samples. To determine the ages of kangaroos, we examined the molar patterns of animals shot. The sex ratios in all age groups are presented in Table 6.1 and compared there with the sex ratio in joeys. The sex ratio of joeys (< 1 year old) was not different statistically from 1:1. The ratio of older animals, up to three-year-olds, was similarly even. Thereafter, there were fewer and fewer males to the point where females outnumbered males five to one in old age (> 12 years). It seems, then, that the mortality of males increasingly exceeded that of females once they reach three years old. Table 6.1. Change in sex ratio with age. The ratio is calculated by the number of males divided by the number of females. Data are from Newsome (1977).

Age (Years)

< 1 (joey)

2–3

4–7

8–12

> 12

All

Ratio

1.17

0.84

0.49

0.35

0.19

0.59

No. of kangaroos

925

201

519

497

452

2594

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The Red Kangaroo in Central Australia

What significant changes take place at that age? There appear to be two of them. Sexual maturity in males is reached between three and 3.5 years. At this age also, the larger size of the male first becomes apparent. Females grow little more past that age in Central Australia, most of them staying between 20 and 25 kg in weight. Many adult males, however, grow to twice that weight, some growing as large as 50–60 kg. So, what causes the mortality? The advantage of large size to the male red kangaroo has never been studied. Presumably there is a link with sexual success, just as in seals. Seals haul themselves up onto beaches to breed seasonally. Dominant bulls attract harems around them and fight off lesser male seals. Red kangaroos are not seasonal breeders, however, and so perhaps it is an advantage to be big if you are a buck and competing for a doe on heat. With does outnumbering bucks five to one, however, that might seem a strange proposition. Remember, however, that females, though continuous breeders, do not breed synchronously. Loss of joeys at any time during pouch life (which lasts eight months), plus carrying seasonal conditions, staggers breeding in the females. So competition for oestrous does could be a real possibility. Since size in the male indicates age and therefore the ability to survive in a harsh environment, then it has presumably been an evolutionary advantage to link age and size in the males to achieve better breeding. But why not in the female? There are no published data on this, but I had the feeling that the younger females were the ones which

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ceased to breed in hard times. So, from my data, I chose two samples for analysis. The first was from October 1959 or the beginning of the long drought (1958–1965; i.e. just after a long run of good years), and the second in December 1961, well into the long drought and, in fact, eight months since the last rainfall. The tooth pattern and weight of each adult female was compared with its reproductive status (Table 6.2). Table 6.2 shows that regardless of whether weight or molar pattern was used for comparison, there was the same result in each drought sample. The proportion of breeders was lowest in the young age bracket (2.9–5.7). The difference was less marked in the sample later in the drought (i.e. 1961), quite simply because the deeper the drought, the more females were affected by it. Males, too, lose reproductive condition during hot drought weather in two ways (Chapter 4). Some cease sperm production and, in others, the quantity and size of interstitium declines. Both defects appear in some bucks, Table 6.2. Percentage of female red kangaroos that were breeding during drought, in relation to tooth class (molar eruption stage) and weight. Molar eruption stage

Deduced age (year)

Bodyweight (kg)

Percentage (%) breeding (1959: mild drought)

Percentage (%) breeding (1961: severe drought)

2.0–2.8

2.9–5.7

–

49

17

3.0–3.8

6.8–13.5

–

76

28

> 4.0

> 15.9

–

76

49

–

–

12–18

34

34

–

–

19–23

67

31

–

–

> 23

79

62

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The Red Kangaroo in Central Australia

and of course, some remain potent. There is no difference in the average molar patterns between potent males and those producing no sperm. Those with reduced interstitium, however, were younger (Table 6.3), even when data from those bucks suffering from both defects were amalgamated. So there is evidence for both males and females in the older ranges being the better breeders. The reasons are probably quite different. In the males, we thought that the cause may be social, the competition for a receptive female. However, the female is hardly likely to compete for a male. So the cause must lie elsewhere. Many social animals live in groups, e.g. wolves. The evidence from them is clear, that dominant animals breed more than subordinate ones despite good health in all ages. Somehow, the stigma of being a social inferior suppresses breeding. Red kangaroos do not form tight social groups. So the cause of lessened breeding in younger animals may have other causes. One of them appears to be nutrition, because the non-breeders in any tooth class are lighter Table 6.3. Reproductive state of 171 male red kangaroos during a drought. Molar eruption stage

Sperm production absent (%)

Reduced interstitium (%)

Both defects (%)

Full breeding potential (%)

2.0–2.8

5.8

3.5

1.8

4.1

3.0–3.8

31.6

4.7

10.5

19.3

> 4.0

9.9

0

1.2

7.6

Mean tooth class

3.6

2.8

3.1

3.3

Mean deduced age (year)

7.5

5.1

8

10

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than the breeders by ~4–19% in the early part of a drought, less so later on (Table 6.4). Thus, as drought wears on, it apparently affects all females, lessening the difference in weight between breeders and non-breeders. So, either the older does know best where to find food or they are able to corner the best of it using their weight. They probably use both methods. As mentioned previously, a kangaroo usually approaches from behind, grabs around the waist and pushes it aside (Russell 1974). Sometimes it utters ‘Ha’ at the same time. Kangaroos frequently change shelter trees during the day; the mere approach of a large male is enough to shift the occupant off a particular patch of shade. No study of behaviour has been made at night; but these same methods, active and passive, are probably used to secure the best food. So competition for basic resources, though never studied directly, appears certain at the individual level, and Table 6.4. Lower weight of young anoestrous females. Ascribed age (years) based on molar tooth class

Breeding females (kg)

Anoestrous females (kg)

Drop in weight (%)

Mild drought 1–2

22.2

18

19

2–5

23.2

21.2

4

5–12

23.9

22.8

0

Severe drought 1–2

–

15.1

–

2–5

22.1

19.9

10

5–12

22.0

21.4

0

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The Red Kangaroo in Central Australia

this manifests itself in a very real way for the losers – less food and consequently less breeding. The interstitium is thought to be influenced by nutrition. That the younger males are affected most, indicates that the larger males may commandeer more than their share of food, just as in females. I have been unable to measure on a large scale the effects of the density of red kangaroos on food supply or breeding. During every sample, the mean numbers of red kangaroos per kilometre was calculated for transects ~100 km long, so the percent of non-breeding female kangaroos could be plotted against the quantity of food, the severity of the drought, and the density of kangaroos, either independently or together using standard statistical techniques. The Drought Index was the best predictor. Thus, it seems that there was no escaping the heat load in summer regardless of age. There were very few females 6–12 months old (tooth class M1) in the sample from late in the drought, 5% only compared with 35% when the drought began two years earlier. This was a consequence of poor reproduction. The effect of the widely fluctuating rainfall on the agestructure of the kangaroos is forcibly revealed in one simple exercise. When the ages of all 2000 kangaroos in my samples were estimated and their years of birth established, I discovered that I had been sampling an unusually top-heavy population. Most of my kangaroos were old, some very old. Over one-third of these were more than 10 years old, and a quarter of them had been born in the 1940s when I was a schoolboy. I was looking at history.

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The rainfall record from 1940 to 1962 was utilised to calculate how many months each year pastures remained green. The numbers of animals born in each year are clearly related to periods of pasture growth as shown in Fig. 6.1, and establish the great importance of unusually wet years for kangaroos. The rain induces great pulses in the long-term population trends – the greater the run of good years, the greater the pulse. The 1940s had been reasonably wet years. Almost all young born in that decade would have survived. Thereafter, rainfall was depressed except for a short burst for 1954–1956. Then the long drought set in, and a few kangaroos would have survived to adulthood between 1957 and 1965. Kangaroos would therefore 300

No. of samples

1 2 10 16 16 16 16 16 16 16 16 16 16 14 6 2

(1) (2) (3) (8) (8) (8) (8) (8)

Kangaroos

200

5 100

0 1941

1950

1960

Months of growth

10

0

Figure 6.1: Estimated years of birth of 1991 red kangaroos from Central Australia and the estimated periods of pasture growth each year (line). The solid histogram represents kangaroos ‘aged’ on molar eruption, and the dotted one, old animals ‘aged’ by the stage of molar eruption and molar progression averaged. Figure is from Newsome (1977) .

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need to be relatively long-lived in order to persist in Central Australia. Just how long-lived they would have to be leads to another historical review, on the rainfall for the century since records were first kept in 1875. For full survival of joeys, pastures must stay green for eight months. For 50% survival, the eight months need only be interrupted by 1.5 months of drought in summer, and 2.5 months in winter. So the rainfall record was reviewed with these criteria in mind (Table 6.5). Thus, there were 17 periods favouring full survival of joeys in the century, the periods being eight to 36 months long and occupying 18% of the total time. Their mean length was 12.5 months. The longest run of good years was 2.8 years from 1920–1923. The 29 less favourable periods covered 31% of the century and averaged 13 months in length. The largest span of intermittent growth was 3.1 years, also in 1920–1923. The rains in 1973–1976, being all-time records, may provide longer spans. Though periods of pasture growth regenerate kangaroo populations, it is the interval between good seasons that Table 6.5. Number and length of periods favouring survival of joeys 1875– 1974. Data are from Newsome (1977).

Months

8–12

12–24

24–36

Totals

100% survival

12

4

1

17

50% survival

21

6

2

29

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Table 6.6. Intervals between growing periods favouring survival of joeys. Data are from Newsome (1977).

Months

0–50

50–100

100–200

Totals

100% survival

8

4

4

16

50% survival

23

4

1

28

causes their decline (Table 6.6). The average interval was a whopping 5.5 years long between periods favouring 100% survival of joeys, and 2.3 years between less favourable periods. No interval between these periods exceeded 13 years and most (22 out of 28) were less than four years. Intervals between full survival are longer, half exceeding four years, four exceeding 11 years and three, 13 years. This means the probability that enough rain will fall for 100% survival is about one year in six. The probability that a joey’s first year out of the pouch will also be favourable falls to one year in 16. And the probability that pastures will remain green till it reaches sexual maturity at three years old is a quite low, one in 33. The respective probabilities for joeys faced with only a 50% chance of survival is one year in three for pouch life, and one in seven for the next year, and one in 20 till three years old. The long intervals between runs of good years will be really telling ecologically. Gaps between two consecutively favourable eight-monthly periods averaged 11 years (range 0–24 years), and between three consecutive times was 22 years (0–44 years). The figures for intervals between 50% survival of young is a little less: 5.5 years (0–14) for two consecutive years and 12 years (0–44).

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The Red Kangaroo in Central Australia

The upper limit to longevity of the red kangaroo is ~15, perhaps 20, years in Central Australia. Thus, the prospects for any doe depending on fully favourable seasons, or even 50% or so, to produce young with a chance of reaching sexual maturity is daunting. It is clear that they must depend upon the local and lesser spasmodic rains to produce recruits. The really wet runs of years, 1920–23, 1945–50, 1966–69 and 1973–75 would have produced population pulses, which are hardly ever large enough to carry the populations from one pulse to the next. The environment of Central Australia appears therefore to be close to the survival limits of the red kangaroo. This conclusion may seem strange in view of the outcry against red kangaroos as too numerous pests. That outcry, however, probably reflects the observation that despite red kangaroo numbers declining in drought, around 80% of those that survive will concentrate their activity in the areas grazed by cattle in the grassy plains between 1.5 and 8 km out from water. Because satisfactory grazing conditions have been created for the red kangaroos by the cattle themselves (see Chapter 3), and because the multitude of artificial watering places across the dry inland plains have now removed any shortage of water, there has been a great increase in drought-refuges for red kangaroos. That is why, in that man-altered environment, the numbers of red kangaroos have increased throughout inland Australia after the introduction of livestock (Fig. 6.2).

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Numbers

STOCKING

PREHISTORY

Time

Figure 6.2: Diagrammatic representation of the great increase in red kangaroos due to changes in the habitat and water availability after livestock were introduced. Modified from Newsome (1971b) .

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7 Ecomythology

Ted Strehlow, who is one of the greatest anthropologists in the world, and arguably the best in Australia, was born in Hermannsburg Lutheran Mission in 1908. His father, Carl Strehlow, was the Lutheran pastor and Superintendent, since 1896, of the Hermannsburg Mission, south-west of Alice Springs. Young Ted would have grown up with Aboriginal buddies as friends and playmates. We gather that Ted’s first language would have been Aranda, his second German, with English a runner-up. Most likely he had an Aboriginal woman as his nanny, for the Missioners and wives were kept more than busy with increasing influxes of Aboriginals into the mission. One of the worst droughts recorded was in the late 1920s peaking in 1928. Aboriginals poured in out of the

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The Red Kangaroo in Central Australia

surrounding bleak landscape. There was another reason, a massacre in the north-west. I find it beyond belief that seven years before I was born, white gentlemen in Central Australia were shooting Aboriginals because they were in retreat to their permanent waterholes from the searing desert drought. Their temporary water had dried up. These were their permanent fallback in drought, but the cattlemen saw it otherwise and awkwardly it was this massacre and the consequent fleeing of the survivors that led to much of Ted Strehlow’s writings. In my early years working on the red kangaroo, I had noticed that several cattle properties had no or few Aboriginal people on them, whereas cattle properties further out had large numbers of Aboriginals. Mostly they camped in the creek some distance from the homesteads. The women kept the household running, the young men tended the cattle. A famous linguist working in Central Australia in my time told me that you could always tell if the camp was happy; there would be kids everywhere. Aboriginals themselves now own the land of that appalling act of cruelty in the north-west. Strehlow recalls how the old men of the tribes invested their songs and creation legends in him. The younger men had come to the cattle stations to work. It was exciting, they loved horses and their strength and endurance. They left also to escape the hegemony of the elders. They were the custodians of the great legends and song cycles whose power continued the survival of all living things and, of course, the Aboriginals themselves. As I understand it, Strehlow felt free to translate what had been invested in him because there were no old red

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kangaroo men left and no young men invested with the sacred song rituals and dances. The happenstance of a young white man, born in Hermannsburg, and steeped in Aboriginality, hearing and speaking the language from his birth, plus the faith the elders had in the young Strehlow, is something that modern Australia should celebrate and rejoice upon. Being born at Hermannsburg automatically meant that Ted had a totemic ancestor. It must be so and the elders would have decided that. One day I found Aranda Traditions (Strehlow 1968) in a bookstore in Alice Springs. It is a smallish book, not easy to read, containing huge amounts of information. However, I became more and more interested in what Strehlow had to say about the animals and plants, the red kangaroo in particular. By then I had almost completed my study of the ecology of the red kangaroo in the outwash plains of the north MacDonnell Ranges (previous chapters). I knew the landscape for over ~7500 km2 very well indeed from the air and on the ground – probably better than the cattlemen themselves. So, as I read Strehlow I could map his sites in my mind’s eye. Patterns took shape, information began to fall into place and ideas emerged. I began to see the possibility of links between the mythological and ecological perceptions. The conjunction of legend and science fascinated me. If correct, then some legends may have a functional basis. In a sense it would be nonsense not to do so. When I visited Strehlow at the University of Adelaide in 1969, he sought information from me and I from him. He wanted to know why so many springs in the MacDonnell Ranges dried up.

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The Red Kangaroo in Central Australia

No one knew at the time, but studies of similar events in the top end found an eight-year delay following suitable rainfall events. I asked about the myths and red kangaroo totemic sites mapped in his book. Strehlow was very cautious, probably because he thought I had worked out too much. Strehlow writes in a beautiful clear heroic style – very impressive. So is how he weaves skeins of thought, ideas and facts through a narrative. Concentrating on one of them so strongly may have allowed me to work out more than I thought. I also went to see Pastor Paul Albrecht, who was a Hermannsburg Missionary in my time at Alice Springs. As expected from Strehlow’s book, there were no kangaroo men north of the MacDonnell Range. However, the kangaroo totem had not died out. It was known that a kangaroo man was living south of Tennant Creek, and I knew of another living at Finke River. They had parts of the sacred red kangaroo song in their heads. And one day, a kangaroo man will be born back on those lands. A kangaroo man was also known at Alcoota station. Pastor Albrecht arranged for me to accompany the mission truck next time they did the rounds of the cattle stations (in 1972). The truck was driven by a highly esteemed elder and current chair of the Alice Springs Aboriginal Council. I knew the manager of Alcoota quite well so I was welcome there. I had by that time started to work on dingoes as a pest to the cattle industry and travelled far more widely than during

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my kangaroo days. This had allowed me time to go looking for prospective totemic sites based on remote published maps and on the contents of some published lyrics. I believed (at that time) that indeed I had been highly fortunate to have visited Krantji (a famous red kangaroo totemic site), if not the immediate soak then a nearby closely related site. At Alcoota, I was introduced to Lame Tom Etaralakaka (meaning that white shape on a red kangaroo’s chest). Note the letters ‘ara’ in the name. That is the Aranda name for the red kangaroo. Etaralakaka belonged to the Unmatjira people related to the Aranda. Indeed it turned out that the red kangaroo legend and song has its beginnings at Krantji – but the Unmatjira were not allowed to visit the soak. That I had done so played a more important role in what I learnt from the old man that I could have imagined. I was asked, ‘You bin to that Krantji, You.’ I answered, ‘Yes’. They quizzed me further. Another elder said, ‘Oh you big big man.’ The publication reprint that follows, took another seven years of investigations and the linguistic capabilities of Ken Hale, an American professor then living in Alice Springs. From the songs that were sung at Alcoota, Alan concluded that the red kangaroo myths had an underlying ecological rationale. It was plain evidence that the Aboriginal people who created these legends were well acquainted with the ecology of the red kangaroo.

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The Red Kangaroo in Central Australia

The following text is reproduced as per the original: Newsome A.E. (1980) The Eco-Mythology of the Red Kangaroo in Central Australia. Mankind 12(4), 327–333. It is reproduced with kind permission from Wiley.

The Eco-Mythology of the Red Kangaroo in Central Australia A. E. NEWSOME* Ecologically, the red kangaroo (Macropus rufus) in central Australia depends on the availability of green herbage and shady trees. These resources are present in greatest abundance in a minor habitat, the better watered creek systems, especially during drought. In Aranda mythology the major totemic sites for the red kangaroo coincide with the most favourable habitat for the species. Another aspect of the mythology is associated with the ecology. Whether the totemic ancestors travelled overland or supernaturally (underground, or on big winds) is related to the favourability or otherwise of habitats between totemic sites. This paper documents an interesting congruence of myth and reality and suggests that myth may have an underlying ecological rationale.

I. Introduction The lands formerly occupied by the northern Aranda in central Australia provide much good grazing for the red *

Division of Wildlife Research, CSIRO, P.O. Box 84; Lyneham, A.C.T. 2602. MS received May, 1980, accepted September, 1980.

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kangaroo (Macropus rufus) (Strehlow, 1947, 1971; Newsome, 1965a). Particularly favoured are the drainage lines and plains north of the Macdonnell Range and its outliers. The watercourses emanate in the ranges, drain the broad grassy flats which flank the range, and flood-out onto the neighbouring expanse of mulga scrub (Acacia aneura). Beyond lies desert of little use to the kangaroo. Before the advent of white man and his ruminant stock, this region was waterless except after rain. Indeed, according to Aboriginal mythology, mulga parrots (Psephotus varius), brought water to their nephews, the red kangaroo, by night, carrying it from distant places in hide-bag of kangaroo skin (Strehlow, 1947). Now that bores or dams have been sunk every 8 to 15 km across the land for cattle, water is no longer in short supply. The greatest benefit to the kangaroos may not be the water itself, however, so much as the greatly changed pastures due to cattle and sheep grazing out from these artificial waters especially on the open plains (Newsome, 1965a, b). These same changes have brought extinction or rarity to smaller members of the kangaroo family (Bettongia lesueur, Lagorchestes conspicillatus, Onychogalea lunata) through removal of long grass for shelter. (Newsome, 1971, 1975). The evidence for the mythology for the red kangaroo having an ecological basis is now presented in detail.

II. The Mythology of the Red Kangaroo The floodout of Amburla Creek is a favourite feeding ground for the kangaroos (Fig. 1). The water-bore sunk

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The Red Kangaroo in Central Australia

there is named Karanji, and it lies only about 5 km east of Krantji, the most famous totemic site for the red kangaroo (arara, or ara colloquially to the Aranda) (Strehlow, 1947, 1971). The proximity of these places and the similarity in the place-names led me to pursue the idea that there may be direct links between the mythology and ecology of that most important animal of the plains, the red kangaroo. In so doing, I was greatly helped by many people. The initial prompt came from the writings of the late T. G. H. Strehlow (1947, 1971) plus a discussion held with him in Adelaide in 1969. Thanks later to Pastor Paul Albrecht of Alice Springs, I was introduced at Alcoota in 1972 to an old Unmatjira (relatives colingual with the Aranda), Lame Tom Etaralakaka, a red kangaroo man whose name means that white chest stripe of red kangaroos. He sang parts of his sacred legend, which, with the owner’s concurrence, was subsequently translated from the tape recording by Ken Hale who marked also the same stanzas in the songs from Krantji published by Strehlow (1971). At Alcoota also were two other old men known to me only as Old George (now dead) and Sandy White. Old George, who was very old and bent, in particular knew the names and general locations of several totemic sites related to the Krantji myths. These names were transcribed phonetically from the tape recording and translated where possible by Ken Hale. More particularly, Old George related that the Krantji myth was an overland, day-time legend, but that lame Tom’s originated with an underground, night-time legend. Both

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totemic journeys began at the same locality, Ajaii, in the western Macdonnell Ranges, in Kukatja country west of the Aranda land (Fig. 1). At Popunya in 1977, Nosepeg Tjonkata and Shorty Lungkata confirmed that Ajaii was the origin of both red kangaroo dreamings which went to the east overland to Krantji and beyond, and to the northeast underground to Arangurunja (see later). No red kangaroo dreaming continued westwards from Ajaii or in any other direction, they claimed, though Strehlow (1964) showed a link to Pitjintjatjara legends from Malupiti in the Petermann Ranges far to the south. Nosepeg also provided the name of a further minor totemic site near Ajaii, and told how Kolakola (which means ‘joey’ kangaroo), a principle in the Krantji legends (Strehlow, 1947, 1971), was carried eastwards by a big wind to the next site known to me, Kititjira (Fig. 1). He was emphatic that there was no red kangaroo site between the two save a minor one quite close to Ajaii at the end of a creek (Fig. 1). He had never seen the site of Krantji, but his brief description of its general locality and what it was like, plus Strehlow’s (1947 and 1971) maps, lead me to believe that I have located it specifically. Others who helped me greatly have been R. Edwards, R. Kimber and A. Yengoyan, and C. Lendon and B. Foran who kindly made available to me their detailed mapping of regional land-systems used for Fig. 1. Totemic sites The Aranda word ‘Krantji’ is ‘Karantja’ to the neighbouring Unmatjera. These two words are derived from Kara, meaning ‘meat’ and arantja, meaning ‘neck’

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The Red Kangaroo in Central Australia

or ‘throat’ (K. Hale, pers. comm.). They shorten to Kirantja meaning ‘animal neck’. (i) Overland legend . The totemic sites named by Old George are as follows, those in brackets not having been located on the maps of Strehlow (1947, 1971) (Fig. 1). Ajaii or Yayayi, Ulumbara, Krantji, Ilbaltja, (Kwanjimba) or (Kunjamba), Tjilpapura, Ilbalintja (the sun totem), Ininta, Katilakurara, (Ilumpa ilpa), (Irknalakarinja arambiljba), (Irknalakarinja ulpiwuna), and Araperka. This line from west to east lies along a sinuous path about 250 km long stretching from Kukatja land, through Western Aranda land and into Northern Aranda land. I have been unable to find any Aboriginal familiar with this line east of Ulumbara. Indeed, the Krantji myths are published only because that moiety has died out (Strehlow, 1971). Note that many of the place-names include the Aranda word for red kangaroo, ara. Old George and Ken Hale have translated some of these names. Krantji is as above. Ilbaltja is a peak in the range near Krantji; ‘ilba’ means the kangaroo’s pouch. Kwanjimba is a claypan. Tjilpapura is the famous totemic site of the marsupial cat (Dasyurus geoffroii) and ‘tjilpa’ is the animal’s name. Krantji and Tjilpapura are the most important totemic sites for the red kangaroo along his overland path. Ininta is the bean tree (Erythrina metroxlon). Katilakurara means ‘kangaroo fighting’ and is a box tree (Eucalyptus intertexta), Ilumpa ilpa is the ghost gum (Eucalyptus papuana); through unmapped, Old George told me that its site is a small sand dune on the 16-mile Creek near Araperka, Irknalakarinja ulpiwuna are probably close

115

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together. The first word means ‘bark belonging to a place’ or ‘place of origin’, ulpa means ‘red ochre’ and iwuna means ‘thrown’. It is probably a place where red ochre was thrown. Araperka, the last site on the chain, was described at Alcoota as the final resting place of the kangaroo. Ara is the red kangaroo, and perka means “charcoal’ or ‘dung’. Atnaperka means ‘colon’ or ‘large intestine’, and so Araperka may mean red kangaroo dung. The Krantji chants are virtually identical with those of Kitjitjira and Ulamba (and with a famous euro (M. robustus) totemic site in the MacDonnell Ranges, Kaput ’ Urbula, meaning ‘black head’) (Strehlow, 1971). Several kangaroo ancestors feature in the myths. Two of them are the great sire of Krantji himself, Krantjirinja, who never travelled far from his soak, and Kolakola, a

Very highly favoured

FLOODOUTS

Highly favoured in drought

OPEN GRASSY PLAINS

Favourable

MU

22°

LG

A

SAVANNAH

Minor habitat

MINOR CREEKS

Favoured after MULGA good rains

Arangurunja MULGA

Unfavourable DESERT Unfavourable

DESERT

RANGES

MULGA

DESERT

ERT

DES

23°

Krantji llbaltja

Ulumbara

Ajaii

llbalintja

GA

L

MU

A

G

UL M

Kitjitjira

Tjilpapura

Ininta

Araberka

Ulumba 0 131°

25

MacDo nnell Ra nges

50 Km 132°

133°

Katilakurara Kapul’Urbula 134°

Figure 1: Totemic sites and favourability of Habitats for the Red Kangaroo

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The Red Kangaroo in Central Australia

great voyager. He left his soak at Tjilpapura (Fig. 1), voyaged to Krantji and then on westward to Ajaii to collect a band of blood avengers, for there had been dark acts at Krantji (Strehlow, 1971). According to Nosepeg, Kolakola and his band were blown back towards Krantji (to Kitjitjira) by a great wind, a joey being left behind at Ulumbara close to Ajaii (Fig. 1). There is a physical gap from Ajaii to Kitjitjira of about 120 km. As reported above Nosepeg insisted that there was no kangaroo totemic site anywhere along it. Strehlow (1971) translated the Krantji ceremonies and some illustrative verses are presented here: I, Kolakola, am hurrying on without delay; From my hollow (at Tjilpapura) I am hurrying on without delay. I, the young kangaroo, am journeying on a far journey without a halt; Leaving behind a thin trail I am journeying on a far journey without a halt. The band arrives at Kitjitjira (Fig. 1), the clearing resounding with the thudding hops of the visitors returning from Ajaii. The local kangaroos were enjoying their food: The black-mouthed ones While feeding smack their lips noisily. Watering heavily at their mouths while feeding they smack their lips noisily.

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The kangaroos sport and fight: In a thick plot of everlasting They are forever thrusting at each other’s foreheads. They become intent on the visitors from Ajaii: The red-faced ones are watching intently The broad-eared ones are watching intently. The most important ceremonies were at Krantji. Totemites approaching the site did so in silence and reverence, already having laid down their weapons some way off to indicate to the ancestors their homage and peaceful intent. They would approach with closed eyes, feeling their way along the rock-face. Most importantly there was no hunting near ceremonial sites. During increase ceremonies, the rocks, trees and sacred hollow (as at Krantji), representing the ancestors, were struck, and every grain dislodged arose as a kangaroo when next it rained: Hail to thee, Krantji, mother of men! Be fruitful in the ancestral embrace, Filled with game for the use of men! The crutch fat is gleaming white, The crutch fat is white like sand The Rock-plate quivers as the avengers arrive: Our Rock-plate of white, fat,— Our Rock-plate is quivering, our Rockplate is quivering and stirring.

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The Red Kangaroo in Central Australia

Our windbreak home of white fat,— Our windbreak home that gleams like sand. Based on the extraordinary metaphors of the Krantji chant, Strehlow’s (1947, 1971) maps, and the description by Nosepeg of Krantji (which he has never visited nor is he entitled to) as a kind of cave, I searched for and believe that I have found it. It is a diminutive soak hidden in a small, quite extraordinary narrow, horizontal cleft under a large outcrop adjacent to a large rock-plate ‘gleaming white’, ‘like white sand’, or ‘white fat’ from a fine coating of limestone deposited from seepage. The northern face of the mountain range has many such limestone seepages and Ilbaltja may be one of them. (ii) The Underground Line. The Unmatjera informants told of myths surrounding Mt Solitare or Arangurunja (note ‘ara’ again in this word) (Fig. 1). The verses sung by Lame Tom have verses in common with the Krantji myths (see above). The song tells of a devil kangaroo who lived near Arangurunja and also was rearing a captive kangaroo to eat. Kolakola, the same mythical ancestor from the Ajaii story, voyaged again from Ajaii, but underground with his avengers in order to kill the devil-kangaroo. The songs describe kangaroos emerging from the ground, their backs shining in the sun. On seeing them the kangaroo-man changes to a devil-man covered with kangaroo fur and having long ears. He plucked the tall flower-stalks from his mother, the mountain spinifex (Triodia basedowi) to spear the kangaroos. Their deaths enraged the captive

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kangaroo who, though wounded, seized the devil-man and drowned him in the nearby rock-hole. The flow of blood from Kolakola’s mob was so great that the dead were washed to this rock-hole also, and all are there today still, as boulders. There are other stanzas reporting the avenging kangaroos digging holes and drinking, lying down to rest, or sportingly jumping over one another’s faces. Another kangaroo became lost from the mob and, not knowing which way to go, fought a mulga tree in frustration. There are stanzas of increase also, making the grass grow and the kangaroos fat. One describes a blue doe with a joey in the pouch.

III. The Ecology of the Red Kangaroo The study of M. rufus included diet (Chippendale, 1968), reproduction (Newsome, 1965c), abundance, distribution and habitat preferences (Newsome, 1965a, b) (see summary Newsome, 1975). All these facets of the kangaroo’s ecology were interlinked, as follows. 1. Diet. Red kangaroos are grass-eaters mainly and require green herbage, which seems odd for a desert animal but explains its habitat preferences (see below). Table 1 illustrates a strong dependence on one particular grass species, ‘Never-fail’ (Eragrostis setifolia), especially during drought. It grows in watercollecting depressions, the floodouts of creeks and gil-gai scattered across the open plains.

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The Red Kangaroo in Central Australia

TABLE 1 Diet (%) Drought

After rain

Eragrostis setifolia

54

24

Other perennial grasses

22

56

Herbs

8

1

Browse

2

1

After Chippendale (1968) (see Newsome 1974).

2. Habitat Preferences. The red kangaroo is a nomad, moving about to find the best food. Aerial surveys were conducted over 6,877 sq km of the Burt Plain with the various habitats: watercourses, open plains, patches of savanna woodland, dense mulga scrubland (Acacia aneura), and the spinifex (Triodia) deserts. During drought, red kangaroos were most abundant along water-courses and open plains, the minority habitats where some green grass persisted, with few in the mulga and desert (Table 2). After good rains generated pastures everywhere, the kangaroos were mostly in savannah, with mulga scrubland and water-courses the next most important (Table 2). In preferred habitats they obtained their vital resources of food and shade in best abundance all the time. Drought being the most taxing time, the distribution of kangaroos was analysed in more detail relative to the supplies of the kangaroo’s vital resources, food and shade (Table 3). The importance of the water-courses, of their floodouts in particular, is highlighted. Floodouts held densities 50% more than the floodplains higher up the water-courses, both of

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which were two to three times more favourable than the minor floodplains and savannah. TABLE 2 Habitat Preferences Habitat Water-courses Open plains Savannah

Density of kangaroos

(no./sq km) Good Seasons

2.0

0.6

5

2.1

0.2

42

0.8

1.2

Area (%) 5

Mulga scrub

16

0.1

0.8

Desert

32

0.1

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Administration, Technical Bulletin No. 1. Chippendale GM (1968b) The plants grazed by red kangaroos, Megaleia rufa (Desmarest) in central Australia. Proceedings of the Linnean Society of New South Wales 93, 98–110. Christian CS, Stewart GA (1953) ‘General report on survey of Katherine– Darwin region, 1946’. CSIRO Aust. Land. Res. Ser. No. 1. Dawson TJ, Brown GD (1970) A comparison of the insulative and reflective properties of the fur of desert kangaroos. Comparative Biochemistry and Physiology 37, 23–38. doi:10.1016/0010406X(70)90954-0 Dawson TJ, Denny MJS (1969a) A bioclimatical

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comparison of the summer day microenvironments of two species of arid zone kangaroo. Ecology 50, 328–332. doi:10.2307/ 1934861 Dawson TJ, Denny MJS (1969b) Seasonal variation in the plasma and the urine electrolyte concentration of the arid zone kangaroos Megaleia rufa and the Macropus robustus. Australian Journal of Zoology 17, 777–784. doi:10.1071/ ZO9690777 Dawson TJ, Hulbert AJ (1970) Standard metabolism, body temperature, and surface areas of Australian marsupials. The American Journal of Physiology 218, 1233–1238. Dawson TJ, Denny MJS, Hulbert AJ (1969) Thermal balance of the Macropodid marsupial Macropus eugenii Desmarest. Comparative Biochemistry and Physiology 31, 645–653. doi:10.1016/0010406X(69)90065-6

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Merrilees D (1968) Man the destroyer: late Quaternary changes in the Australian marsupial fauna. Royal Society of Western Australia 51, 1–24. Newsome AE (1964a) Anoestrus in the red kangaroo Megaleia rufa (Desmarest). Australian Journal of Zoology 12, 9–17. doi:10.1071/ ZO9640009 Newsome AE (1964b) Oestrus in the lactating red kangaroo. Australian Journal of Zoology 12, 315–321. doi:10.1071/ ZO9640315 Newsome AE (1965a) Reproduction in natural populations of the red kangaroo, Megaleia rufa (Desmarest), in Central Australia. Australian Journal of Zoology 13, 735–759. doi:10.1071/ ZO9650735 Newsome AE (1965b) The abundance of red kangaroos, Megaleia rufa

(Desmarest), in Central Australia. Australian Journal of Zoology 13, 269–287. doi:10.1071/ ZO9650269 Newsome AE (1965c) The distribution of red kangaroos, Megaleia rufa (Desmarest), about sources of persistent food and water in central Australia. Australian Journal of Zoology 13, 289–300. doi:10.1071/ ZO9650289 Newsome AE (1966a) Estimating the severity of drought. Nature 209, 904. doi:10.1038/ 209904a0 Newsome AE (1966b) The influence of food on breeding in the red kangaroo in central Australia. CSIRO Wildlife Research 11, 187–196. doi:10.1071/CWR9660187 Newsome AE (1971a) Competition between wildlife and domestic livestock. Australian

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Index Aboriginal people arid conditions and 5, 6–7 arrival of 2 Burke and Wills expedition and 30 cattle grazing and 106 Finke River and 17 food preparation skills 12–14 giant marsupials and 127 hunting skills ix, x, 11–12 kangaroo feeding grounds and 42 Newsome and xxiv red kangaroo mythology and 68 Strehlow and 107–8 Adelaide 11, 127 adiabatic warming 19, 128 aerial surveys xv, 34–40, 43–4 age 93 breeding patterns and 96–8 survival rates and 100–3 Albrecht, Paul 108

Alcoota land-system 30 Alice Springs xxi, xxiii, 7, 9, 18, 20, 34, 42, 50, 79, 105, 108 meteorological information 23, 24 water usage study 83–5 Amburla Station 50 anatomy, red kangaroo and euro 10 Andrewartha, H.G. xix Animal Industry Branch (NT) xxi annual grasses 71 anoestrus, female reproduction (red kangaroo) vi, 53, 54, 55, 56–8, 129 antechinus 128 antelope 85 antilopine kangaroo (Osphranter antilopinus) 7, 8 ants 87 Ara vii Arabian oryx (Oryx leucoryx) 67, 81 Aranda people vii, viii, 5, 105, 109

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The Red Kangaroo in Central Australia

Aranda Traditions (Strehlow) 107 arid conditions 2–3, 19–27 Aboriginal people and 5, 6–7 Aristida 69 Attack Creek 6 Beck, Colin 38 biological survival, Central Australia 16, 22 bird swarms 22 birth rates, pasture growth and 99 blastocyst 48, 49, 53, 58, 128–9 bloodwood (Corymbia terminalis) (Eucalyptus terminalis) 31, 128 blue fur, heat reflectance 82 blue grass (Bothriochloa decipiens) 31 body temperature 81 body weight, comparative 94, 96–7 Boen land-system 31 breeding patterns 94–100 brushtail possum 128 budgerigar (Melopsittacus undulatus) xii, 22, 67 Burke, Robert O’Hara 4, 127 Burt Plain x, xi, xii, xiv, 18, 19, 34, 36, 50, 54, 74, 89 diet study 70

land-systems 29 Bush Park land-system 31 button grass (Dactyloctenium radulans) 31 Cambrian rocks 17, 128 camel (Camelus dromedarius) 23, 63, 67, 81, 84 cattle grazing industry 23, 65, 69, 108 Aboriginal people and 106 food supply and xiii, 64 red kangaroo and v, vi, 45, 102–3 Caughley, G. 40 Ceilidh 37 cellular detritus 60 Central Australia v–viii, xx–xxvi, xxviii, 79, 139, 143, 144 birth rates 99 exploration of 127 life-history studies 11 longevity rates 102 mapping 28–9 pasture growth 24–6 red kangaroo and 5–6, 8–9, 69, 70, 99 slaughter of Aboriginal people 106 Cessna 34

I n d ex

channel country 39 Chihuahua Desert 20 Chippendale, G., diet study 40, 69 clayey soils xii, 27, 28, 30 climate, Central Australia 19–27 continental shield, Australia 16, 17 coolabah (Eucalyptus coolibah) 32 Cooper’s Creek 4, 30, 127 corpus luteum 56, 129 couch grass (Cynodon dactylon) 79–80 crab-holes 30 creation legends, Aboriginal 106 creek systems 41, 42 Commonwealth Scientific and Industrial Research Organisation (CSIRO) xxviii, 28 curly windmill grass (Chloris acicularis) (Enteropogon acicularis) 27, 128 Darwin xxi, 19, 22 Dearnley, Stephen xix, xx dehydration 78, 86 delayed implantation 48–9 Delmore Downs xii density survey method 40–1, 44–5

141

Desert Block 37 deserts 32, 34, 41, 67 Diamantina River 17 diamond dove (Geopelia cuneata) 67 Dickman, Chris xxvii diet 69–78 dingo (Canis dingo) 88, 108 Diprotodon 1 discovery experience, Newsome viii, xx, xxi distribution, red kangaroo 33–45 Dreamtime vii drought 25, 27 Australia and 2–3 breeding patterns and 9, 43, 52, 53–5, 56–8, 61, 62, 94–102, 129 Central Australia vi, 15–16, 20 diet and 70–3, 75, 76 families and 87–8 group size and 88 late 1950s 99 1920s 105–6 1958 27, 31 1961–64 36–7, 39, 42, 95 sterilisation and 62, 64–5 survival rates 100–2 drought-hardy fauna 5

142

The Red Kangaroo in Central Australia

Drought Index 27, 54, 55, 98, 129 drought refuges vii dry grass 73, 75, 128 dust walls 23 Ealey, Tim v, 76 echidna (Tachyglossus aculeatus) 82 ecomythology, red kangaroo 105–25 eland (Taurotragus oryx) 85 electrolytes 84 embryo 48, 128–9 endocrine system 129 Eragrostis setifolia 27, 69, 71 Etaralakaka, Lame Tom 109 euro (wallaroo) (Osphranter robustus) 2, 8, 9, 76–7 European settlement 3, 6, 7 Eva Downs 79 evaporation 23, 24, 129 family groupings (red kangaroo), lack of 87–8, 89 feasting, Aboriginal people 13–14 female red kangaroo 8, 52 anoestrus and 56–8 fur reflectance 81–2, 83 protection of 65 reproductive biology field studies xxii, 49–52, 73

fighting behaviours 91–2 Finke River 17–18, 22, 108 Finlayson, Hedley xxiv Flinders grass (Iseilema spp.) 31 flooding, Finke River 17–18 foeto-placental control 57, 129–30 Follicle Stimulating Hormone (FSH) 57, 130 food preparation, Aboriginal people 12–13 food supply 67–86, 97 breeding patterns and 98 cattle grazing and 64 density and 40–2 foramen magnum 9 forbs (herbaceous dicotyledons) 28, 70, 71, 72, 74, 77 Frith, Harry v fur heat reflectance 81–3 Georgina River 17 germinal cells 59 giant marsupials 1–2 giant yellow daisy (Senecio magnificus) 31 Gibson, Alfred 4 Giles, Ernest 4, 127 gilgais xiii, 27, 28, 30, 72

I n d ex

gnarled corkwood (Hakea intermedia) 31 gold miners 6 Grant’s gazelle (Nanger granti) 81 grasses, cell samples 69, 70, 71 grassy plains 28, 30, 31, 42, 77 Great Dividing Range 8 green herbage diet xiii, 39, 40, 41, 70–3, 74, 75 Drought Index and 129 group dynamics and 89 joey survival and 100–1 protein and 79 reproduction rate and 64 water content of 79–80, 84, 85 grey kangaroo (Macropus giganteus) 7–8 grooming behaviour 91 group size 88–103 Gulf of Carpentaria 127 Haast’s Bluff ix, x, 11 Hale, Ken 109 Hamilton Downs 26, 37, 50, 54 Hamilton land-system 30 heat tolerance, male potency and 60–1, 62–4 Hermannsburg Mission 105, 107, 108

143

hill kangaroo 76, 81, 85, 92 hip-holes xvi, 45, 80, 81, 128 hormones 57, 129, 130 house mouse (Mus musculus) 48 hunting skills, Aboriginal people 11–12 Indian Ocean Dipole 128 inland sea 1973–74 18 interstitium size, drought severity and 61, 62, 95–6, 98 invader species 31 Jackson, Joe 79 Johnson, Ken xxvii Jones, Frederic Wood

47

Kanandra land-system 31 kangaroo men 108 kerosene grass (Aristida spp.) 30, 32 Kirkpatrick, Tom v Krantji 109 Lake Eyre 17, 22 landforms, Central Australia 16–19 land grain 19 land-systems 28 lanes method, aerial survey 39–40 Larapinta (Finke River)

17

144

The Red Kangaroo in Central Australia

large rivers, Central Australia 17 late Pleistocene 2 Leichhardt, Ludwig 4, 127 life-history studies 11 Limestone Bore x longevity rates 102 Low, Bill xxvii–xxviii low-pressure systems 20, 21 Luteinising Hormone (LH) 130 MacDonnell Ranges v, xi, 16, 18, 19, 30, 34, 50, 107 McGrath land-system 29 MacMillen, Dick xxvii macropodids, pregnancy lactation among 64 Macumba River 17 male red kangaroo drought diet 76 fur reflectance 81–2, 83 mortality 93 reproduction 58–65 Mankind viii, xxiv Marble Bar 76 marsupial lawn 45, 128 marsupial lion (Thylacoleo carnifex) 1, 127 marsupials 61, 82, 83 mating habits 88, 94 meiotic division, failure of 59 metabolic rate, water retention and 83, 84

Milton Park Station 50 Mitchell grass (Astrebla pectinata) vii, xii, 27, 30 mob behaviour, abundance and 89–91, 128 moisture-bearing stock feed 68 molar eruption patterns, females 95 monsoons 21 Mount Hay x, 11, 36, 41 Mount Liebig 11, 12 movement patterns 44–5 mulga parrot (Psephotus varius) 68 mulga scrub (Acacia aneura) xi, 11, 18, 28, 30, 31, 32, 34, 38, 39, 42 red kangaroo density numbers 43–4, 45 mulga woodlands xiv, 41, 70–1, 80 Murray River 127 mythology, ecology and 90, 105–25 nardoo (Marsilea exarata) xiii, 30 nasal chamber 9, 10 native pastures 30 neverfail (Eragrostis setifolia) xiii, 27, 30, 70, 72, 73 Newcastle Waters 7

I n d ex

New Guinea 64 Newsome, Alan xix–xx, 128 Alzheimer’s disease and xxi discovery experience xxiii–xxiv photograph of xxvi red kangaroo and v–viii Newsome, Thomas viii New South Wales v, 79, 81, 84, 85, 89 nitrogen minimum 78 non-continuous breeding 53 non-drinking species 85 Northern Territory xxi, 7 north-west Australia 76, 80, 92 nutrition 67–86 oat grass (Enneapogon spp.) 30–1 oestrous cycle 49, 94 open plains 30–1, 34, 38, 41, 42, 64 red kangaroo density numbers on 44, 45 Overland Telegraph 19 Palaeozoic Era 128 panting 78, 81 parakeelya (Calandrinia balonensis) 68 pasture fouling 9

145

pasture growth, birth rate and 24–6, 99, 100–1 perennial grasses 27, 45, 70, 71, 72–3 photographs, Newsome expeditions ix, xv, xvi, xxv placental mammals 58, 82, 83, 84, 130 plant cell taxonomy, Chippendale and 69–70 platypus (Ornithorhynchus anatinus) 82 polygamy 130 population recruitment vi, 102–3 pouch-young xvi, 49, 52, 53, 54, 56 Precambrian rocks 17, 128 pregnancy length 47–8 pregnancy rate drought sterilisation and 62, 63 historical mechanisms 64 prevailing winds, Central Australia 90 Procoptodon 1 prolactin 57 protein requirements 73, 77, 79

146

The Red Kangaroo in Central Australia

quadrats 38–9, 40, 43 Quarantine Paddock 90 Queensland v, 39, 127 quokka (Setonix brachyurus) 48, 49 radiant energy, deserts 78 rainfall averages Alice Springs 24 Hamilton Downs 27 Australia 25 rainfall deficiency 19 rainfall events 25 breeding patterns and 39, 42, 43, 53–4, 99, 100–1 Central Australia 20, 21, 23–4 green herbage and 74 March 1967 22 perennial grass growth and 72–3 1940s 99 1959 95 1966 43 2009–2012 128 wildflowers and xiii red earths 18, 28 red fur, heat reflectance 82 red kangaroo (Osphranter rufus) 2, 23, 26, 29 Aboriginal mythology and 68, 111–19 dehydration death of 85–6

distribution of 2–3, 5–6, 7, 8–9, 33–45 grassy plains and 5 Newsome and v–viii numbers estimates method 36–7, 38 nutrition 28, 67–86 photographs of ix, xv, xvi quokkas and 49 reproductive biology 47–65 shooting of v, 50–2, 79, 93 sociology 87–103 relative humidity averages, Alice Springs 24 Rijksen, Eveline xxviii river red gum (Eucalyptus camaldulensis) 17, 29 Robin, Libby xxvii rodents, delayed implantation 48–9 Roughley, Fiona xxviii saltbush (Atriplex nummularia) 32 sampling method, red kangaroo reproductive biology surveys 50–3 sand-dunes 32, 34 sand-plains 18, 32, 34 scrotal temperature regulation 63

I n d ex

seals, mating habits 94 seasonal diet, males and females 75 Senna spp. 32 Sertoli cells 59, 60, 130 sex ratios 92–3, 94 shady trees 41, 42, 44, 80, 85, 91 Sharman, G.B. 48 sheep grazing, euro and 76–7 sheet water flow 29 shooters 50–2, 79, 93 short-horn cattle, water retention 84 shrubby tea-tree (Melaleuca glomerata) 32 shrubs 70, 77 sigmoid curve 129 Simpson Desert xxviii, 4, 17, 18, 22, 68, 85, 90, 127 Singleton land-system 32 skin dry-out, drought and 85–6 ‘Sloper’ 6–7 sociology, red kangaroo 87–103 spear throwing ix Spencer, Emma xxviii sperm production, drought and 59–61, 95, 98 spermatids 59, 130 spermatocytes 59, 130 spermatogenesis, impaired 60–1

147

spermatogonia 59, 130 spermatozoa 59, 130 spinifex (Triodia spp.) xiv, 18, 28, 32, 77, 78 spinifex hopping mouse (Notomys alexis) 67 sporocarps 30 Stephens, Dean 52, 79 Sthenurus 1, 2 stocked country 9, 11 storm activity 23 stratified random samples 51–2 Strehlow, Carl 105 Strehlow, Ted 105–8 Stuart, John McDouall 4–5, 6, 10–11, 17, 34, 127 Stuart Highway 18, 19, 38 study area 18–19 Sturt, Charles 3–4, 127 sucking stimulus 48, 49 summer temperatures 20–1, 82 survival rates, age and 100–3 Tanami Desert xxiii, 6, 21 temperature averages, Alice Springs 24 Templebar Creek 90 Tennant Creek 7, 108 termites 87 testes, heat and 60, 62 Thompson, Jane xxviii

148

The Red Kangaroo in Central Australia

threat displays 91 Titra land-system 32 Todd River 17 Top End 7 topi (Damaliscus korrigum) 85 totemic sites 107, 108 transects 50, 98 treeless plains 30 trees 32, 70 as diet 71, 74 tritium 84 tropical air stream 21, 22 Tyndale-Biscoe, Hugh xxvii Undippa land-system 30 University of Queensland xxi University of Sydney xxviii, 40 Unmatjira people 109 unstocked country 11 upper incisor teeth 10 urea concentration 67–8, 78–9, 84 uterus, female red kangaroo 56–7, 129

watering places 34, 76, 102 drying out of 107–8 McGrath land-system 29 water physiology 68, 78–86 water supply, mulga and 28 weeping ironwood (Acacia estrophiolata) 31 Western Australia 69, 79, 127 white daisy (Helipterum floribundum) 28, 74 wild flowers xiii, 28 wild kangaroos, water retention 84–5 Wills, William John 4, 127 winter, Central Australia 20 witchetty bush (Acacia kempeana) 32 wolves (Canis spp.), family groups 87 woodlands 31–2, 38 woollybutt (Eragrostis eriopoda) 31, 32

vasa efferentia 60, 130 vegetation, Central Australia 27–32, 34

Yamba Station 50 yellow daisy (Rhodanthe charsleyae) 28, 128 young anoestrous females, weight 97 young-at-foot, deaths of 52, 54, 55

wallabies vi, 2 Warramunga people

zebra finch (Taeniopygia castanotis) 22

6