Bird Minds: Cognition and Behaviour of Australian Native Birds

By Gisela Kaplan

In her comprehensive and carefully crafted book, Gisela Kaplan demonstrates how intelligent and emotional Australian birds can be. She describes complex behaviours such as grieving, deception, problem solving and the use of tools. Many Australian birds cooperate and defend each other, and exceptional ones go fishing by throwing breadcrumbs in the water, extract poisonous parts from prey and use tools to crack open eggshells and mussels. The author brings together evidence of many such cognitive abilities, suggesting plausible reasons for their appearance in Australian birds.

Bird Minds is the first attempt to shine a critical and scientific light on the cognitive behaviour of Australian land birds. In this fascinating volume, the author also presents recent changes in our understanding of the avian brain and links these to life histories and longevity.

Following on from Gisela’s well-received books, Australian Magpie and Tawny Frogmouth, as well as two earlier titles on birds, Bird Minds contends that the unique and often difficult conditions of Australia's environment have been crucial for the evolution of unusual complexities in avian cognition and behaviour.

This book is written for a general audience, especially amateur ornithologists and naturalists but it will equally appeal to specialists in bird behaviour and students working in biology, comparative psychology, cognitive ecology, field ornithology, zoology, aviculture and animal welfare. It will also be of interests to veterinarians, zoo personnel, bird lovers and members of other groups concerned with birds.

Recipient of a 2016 Whitley Award commendation for Behavioural Zoology

• Language: English
• Publisher: CSIRO PUBLISHING
• Release date: Aug 3, 2015
• ISBN: 9781486300204

Gisela Kaplan

Gisela Kaplan is Emeritus Professor of Animal Behaviour at the University of New England and an Honorary Professor at the Queensland Brain Institute. She is the author of more than 250 research articles and has conducted ground-breaking research into vocal learning, communication and cognition in birds and other vertebrates. She holds two PhDs and an honorary DSc for her contributions to life sciences. In addition to extensive field research on birds, for the past two decades she has also raised and rehabilitated injured native birds. Her other recent books include Bird Minds: Cognition and Behaviour of Australian Native Birds and Tawny Frogmouth.

Book preview

Preface

The idea for this book had its beginning some 15 years ago when our galah, at the age of 75, learned new words. If ever there was evidence of a plastic brain, he showed it convincingly but there was relatively little to which it could be related in Australian species at the time. There were few papers that discussed the cognitive ability of Australian cockatoos, or other birds for that matter. Of course, there had been important ideas and observations about the cognitive and emotional dimensions in a long and weighty history of avian behaviour as the writings by Charles Darwin (1890, 1965, 1981), then Niko Tinbergen (1953), W. H. Thorpe (1956), Konrad Lorenz (1966) and others attest. From the late 1970s onwards, it was once again raised as a possibility that some birds and other animals may have plastic brains (Kroodsma and Miller 1996), may have minds of their own and are capable of actions beyond those that are ‘pre-programmed’, adaptive or merely copied from others (Griffin 1984, 1992; Roitblat 1987; Ristau 1991; Rogers 1997; Basil et al. 1996; Balda et al. 1998).

The last decades have been extremely exciting for anyone in animal behaviour working with birds, primates or a range of other species. For a host of reasons, the last decades have seen many breathtaking discoveries that have changed forever the landscape of our knowledge about animal cognition and related fields. It is now hard to imagine how people thought before the 1980s, so vast have the changes been, be this in discoveries in field research or in the identification of new methods or theories resulting in robust data and clear evidence of complex cognition in birds.

Hence, my search for evidence of problem solving, tool use and other indices of ‘intelligence’ in Australian birds became a road of discovery, spreading the search for the printed record to well over 100 years, strewn with new and surprising insights and findings. This book is timely because there are new theories and novel experimental techniques and methods for data collection available that enable us to probe into cognitive processes of birds in previously unimaginable ways.

Vertebrates are able to perform cognitively complex tasks, solve complex problems and generally show behaviour suggesting much more awareness than had once been assumed. Indeed, it is now known that some birds have many of the attributes once thought to be specific to humans and great apes.

Who would have thought that the humble chicken understood object permanence, was capable of distinguishing biological motion, could perceive illusions, could perform basic arithmetic and geometry and even had referential signals for various alarm calls, or that pigeons understand principles of same/different and were capable of quite abstract generalisations as in identifying concepts such as ‘forest’ versus individual trees or shrubs? The problem of having been captive long term somehow seemed to suggest, however, that chickens and pigeons had been selected for these skills because of their long exposure to humans (i.e. their abilities were artefacts that might not pertain to birds in the wild). So the new wave of interest in cognitive ornithology was to find evidence of intelligence in wild-caught birds, either by capturing them and seeing how they behave under experimental conditions in laboratories, or by somehow exposing their cognitive capacity in the wild. Ravens, crows and a few parrots have been riding on a crest of fame fanned by journalists worldwide about their amazing and newly discovered abilities of problem solving, tool using, episodic memory, planning and many other attributes.

There has been a different emphasis in Australia and one that is more than of marginal importance because it deeply altered the way in which avian evolution could be perceived. Eleanor Russell (1989) implored us to think from a Gondwanan perspective. The question is why one should, and the inspiring work in taxonomy gave the answer: birds evolved in Australia. In the last 10–15 years, large-scale DNA-sequence analyses have revolutionised our understanding of the evolution of the world’s avifauna, as Christidis and Norman (2010) explained recently. It has led to an enormously active and exciting period in Australian taxonomy, continuing to correct misconceptions and wrong attributions. The evidence now makes it conclusive that there is a very special relationship between Australia and birds.

I was recently asked whether there is anything special about Australian birds. This was one of those heart-stopping moments when one feels one ought to be able to reply with a few well-expressed sentences and yet make the enormity of the implied misconception clear. But to answer it, I found it necessary to write a whole book in reply.

It will take a while for other countries and for Australians themselves to come to terms with the findings. The misconceptions have been substantial, both in the northern hemisphere and in Australia. One of them arose within the recent social history of Australia. Settlers arriving here in the 19th century, often from the British Isles and continental Europe, were confronted by a land so very strange that the simplest emotional response (of course not the only one) to the strange plants was to call them scrub (good for burning) and the animals inferior (good at best for shooting and eating) and, if possible, replace them with species known and familiar to the new settlers. These same well-meaning settlers produced the largest known transfer of invasive species and foisted on this continent the most large-scale and highly destructive onslaught known on the planet, both in flora or fauna. History must excuse their deeds for they believed indeed that the continent was a barren world where only the lowliest of plants and animals had persisted.

The ironies in these responses were manifold and here is not the place to explore the attitudes to Australian wildlife. Suffice it to say that this new continent, in terms of nationhood and white settlement was truly young and even now perceives itself politically as a young, albeit small, nation. Such discourse of the ‘youngness’ of Australia’s political history is in stark contrast to the ancient culture of Aborigines, who had inhabited this continent more continuously than perhaps any other living culture on the globe. The game of youngness and perhaps historical insignificance played out somewhere far away from the main theatres of the western world contrasts with the very old stage on which it is performed: that is, on a very ancient continent that still bears witness to the very beginnings of life on the planet.

Birds arose in the ancient supercontinent Gondwana, specifically in East Gondwana (now largely Australia) and the birds here today have a long claim to this continent as their home and their only home. They are the avian inheritors of the world. They are unique. Birds evolved alongside dinosaurs but in Eastern Gondwana, unlike the rest of the world, they did not all go extinct 65 million years ago: they crossed that ominous extinction boundary (called K/T boundary) and then experienced long periods of isolation from any other landmass before some of them (the Passerida) managed to radiate out and crossed over the equator to the northern hemisphere and eventually populated the vast land masses of Eurasia and later North America.

Thus, an interest in birds in Australia is not just of regional interest or a quirky hobby that one may or may not pursue. Far from wanting to parallel the ‘Out of Africa’ story of human evolution and radiation, there is something like an ‘Out of Australia’ (or ‘Out of Gondwana’) story to tell about birds and it has now been told repeatedly and well over the past decades (Edwards and Boles 2002; Low 2014). Australia does not have the leftovers of extant birds of the higher latitudes of the northern hemisphere, but over millions of years the feathered species of East Gondwana developed and diversified. Australia is the cradle of all songbirds and many other groups of birds. When Gondwana split up over millions of years and in different stages – shed the South American and African continents, set whole subcontinents, such as India and the Middle East afloat, split off island nations such as New Zealand and New Caledonia – some of that feathered cargo was already on board (as was the case in New Zealand).

One of the compelling reasons for thinking that it is important to be assertive about Australian birds is for the benefit of science. For example, a recent review of a book on tool using in animals (Cunningham 2013) asks that we need to stop cataloguing tool use in animals and start interpreting the findings. This is all well and good for researchers in the northern hemisphere. They have, indeed, catalogued and researched bird behaviour extensively. The problem is that this extensive cataloguing of avian cognitive behaviour tends to include only half the world (largely the northern hemisphere) and, in fact, significantly less in terms of the number of species. The southern hemisphere and the tropics are the bird-rich areas of the world and there are still rather large blank areas of knowledge of South-American and South-East Asian and Austral-Papuan species, let alone a ‘cataloguing’ of their behaviour. The theoretical arguments we make, what various avian qualities we correlate with others, how these are of benefit to the species and when they evolved may, surely, be different for different climate zones. It is quite possible, as I had discovered in birdsong theories, that Australian species just defy the accepted models. The functions of song in magpies, for example, do not fit models constructed for sexually dimorphic and migratory songbirds of high latitudes and refute the conclusions reached by researchers in the northern hemisphere. I have discussed this in greater detail elsewhere (Kaplan 2008c). It is acceptable that some disagreements occur and ought not to surprise. What is less acceptable in my view is the risk that these theories arising in specific localities become universal, as if they stand in for all birds in all places.

Thus it is not good enough to say that the cataloguing can now stop because some people have tested a few species in European or North American laboratories. And these are only very few species indeed, representing possibly not even 1% of all extant birds (worldwide there are about 5800 species of songbirds and a further 4000 avian species that are not songbirds). Leaving out the bird-rich areas of the world would be foolhardy. The southern hemisphere is not a mirror image of the north. There are no equivalents of a platypus in the northern hemisphere, for example, and hence it stands to reason that the behaviour of a platypus ought not to be fitted into theories about, say, small European mammals. Nobody would consider doing so, of course, nor should this happen as far as birds are concerned. The birds that evolved in Australia, and then remained on Australian soil, may have retained certain traits and may have evolved to solve problems in ways for which there may now be little or no correspondence elsewhere in the world. What we know is the tip of the iceberg only and, viewing the theoretical problems from a southern hemispheric perspective, it may not even be the same iceberg.

Australian birds – often beautiful and odd, resourceful and innovative – are not just ‘fair dinkum’ but tough, not just pretty things but also extremely clever, not just simple but remarkably complex and adaptable. It is not only time for a celebration of Australian birds but also time to bring together the scattered information and to develop an overall sense of the evolution, behaviour and life histories of Australian birds.

The source materials for this book were vast as the very lengthy, but by no means exhaustive, reference list attests. In some cases, the sources are of the often unnoticed but extensive research publications and observations by Australian ornithologists over the last 100 years, often not duly acknowledged or appraised overseas, with the result that many observations made in Australia have remained either entirely unknown outside Australia, or have been ignored. The sources also include the many excellent papers produced by Australian scholars and published overseas in learned journals for specialists. Somehow not all of that information makes it back to Australia to inform the friends of native birds, let alone the Australian public generally. Many do not always have access or time to follow the complicated paths of academic publishing.

By bringing the information together here in one narrative, a range of Australian avian qualities will be exposed, showing surprising levels of intelligence. Gone are the days when derogatory expressions such as ‘bird brain’, ‘galah’ or ‘parroting’, while deeply embedded in our language, are analogies for Australian birds, or any birds for that matter. Birds have small brains because they need to be aerodynamically designed but, as we know at least since the invention of the microchip and the ever-increasing capacities of devices to store memory, a substantial amount of information can fit into a very small space. And for this reason, in the first decade of the 21st century some of the most advanced thinkers in neuroscience, ornithology, comparative psychology and ethology set out to show that the neural structures of brains of humans and birds are not all that dissimilar. The last 10 years have seen major breakthroughs in our knowledge of the avian brain and behaviour and we now have a biological underpinning to many of the claims that were speculative before (e.g. about learning, remembering and even the reason for evolving a larger brain and how to maintain it).

The book is organised around several familiar and important topics and theoretical positions in cognitive research concerned with innovations, tool use, problem solving and cooperative breeding, and at the same time deals with these topics in the context of the life histories of Australian landbirds, sometimes also referred to as ‘bush birds’, meaning any bird not deriving its entire food from water environments. Appendix 1 is an additional tool to summarise and systematise our knowledge on these topics. Australian birds are long lived and most of them are social. Moreover, it claims that birds in Australia are intelligent and, by and large, may need to be more so than elsewhere in the world. Of course, any generalisation such as this would be rightly subject to substantial criticism. Invariably, exceptions can be found and perhaps even many. The point of this position is rather to test whether the assumption captures something significant about Australian fauna or something of significance about the Australian continent and climate that shaped its evolution in specific ways. This book can only pose the question and present some suggestive evidence in support of some theories of intelligence in birds and perhaps bring to light the extraordinary skills acquired and adaptations that birds have had to make in Australia.

I am grateful for the consistent and sustained efforts of thousands of ornithologists and the many editors of small journals, often entirely based on voluntary work, of the bird banders and the armies of those who counted the number and species of every bird they saw, who have kept meticulous records of their observations and contributed to The New Atlas of Australian Birds (Barrett et al. 2003) and also to those who contributed to HANZAB, the first comprehensive Handbook of Australian, New Zealand and Antarctic Birds in eight large volumes (HANZAB 1990–2006). There are many more people in Australia who are willing to donate their time to such efforts than probably anywhere else in the world. Lending a hand for a good cause is almost a national characteristic. This is now called community science and has been hotly debated and found to be of major value (Cohn 2008; Cooper et al. 2007; Bonney et al. 2009; Hecht and Cooper 2013). Much of that has been done under expert guidance but there are many observations that are fleeting and unique, some of which cannot yet be explained. Let it never be said in a derogatory way that anecdotal evidence is no evidence. Without this background, we would often not be able to begin any consolidated research efforts. Hence, armed with the tools of ethology and the advances in avian neuroscience and the great advances in avian ecology (behavioural and conservationist), we can and must investigate the abilities and the behaviour of birds, not just for scientific reasons but to improve their chances of survival in a dramatically changing world of the present.

On a personal note, I would like to thank and express my gratitude to those who had a direct and personal input of time into this book, including the entire publishing and production team at CSIRO Publishing. Prof. Lesley Rogers was kind enough to read through the entire manuscript making many valuable and critical suggestions; Nicholas Alexander gave me the opportunity to develop the ideas in this book so that this topic could find a home at CSIRO Publishing. Finally, a special and sincere thank you also to the anonymous international reviewers from the USA and Europe who took the time to make detailed and very constructive comments, contributing to a better outcome of the project that is so close to my heart. I am very appreciative of these generous signs of engagement.

Gisela Kaplan

September 2014

1

Australian conditions and their consequences

Australia has an extraordinary diversity of birds and a fascinating paleontological history (Schodde 2005a). Because the two may belong inextricably together, they need more than a fleeting mention. Climate and land contribute immeasurably to the way in which an organism can develop, diversify and radiate. Climate, for instance, may force migration or encourage permanent settlement. The land may provide for all needs or only for some of them, or it may be unreliable and fickle in the way in which it can support life and, in this case, animals that stay need to have their wits about them. If climate permits and birds can defend year-round all-purpose territories, then this may have social consequences as well: breeding seasons can lengthen and partners may not need to separate after each breeding season. Unreliable food sources or involuntary exposure to many novel situations exerts pressure which in turn may lead to the evolution of a larger brain because this, as some have argued, may require increased behavioural flexibility and lead to the ability to cope with and respond to novel challenges. Indeed, certain circumstances within climate and landscape may require sophisticated perceptual and cognitively advanced abilities (Amiel et al. 2011). Conversely, if chances of survival are better with a bigger brain and greater cognitive abilities, then time and energy are needed to nurture and support a bigger brain (see Chapter 2) and conditions in the environment need to make this possible.

Hence the question where birds first evolved is crucial. This had been a puzzle for a long time and is not a marginal question or of limited interest only to Australia. To trace species to their origin can, after all, also trace certain traits and expose mechanisms of evolution. It is very pleasing to be able to say at the beginning of this book that the question of the origin of birds appears to have been settled once and for all. In 2004, a very telling American paper was published about the origin of birds (Barker et al. 2004). It made headlines everywhere and had an even more important response within Australia. It showed conclusively that passerines (perching birds comprising true songbirds called ‘oscines’ and sub-oscines, that make up two-thirds of the world’s existing avian species) originated in the parts of Gondwana that comprise present-day Australia, New Zealand and Antarctica (Cracraft 2001; Barker et al. 2004). This was a landmark publication and laid to rest a 200-year controversy between southern and northern hemisphere scholars.

The Australian Museum and researchers, such as Christidis and many other scholars in Australia, had argued for decades that the origin of birds was Gondwana. When interviewed for his response to this publication by the ABC Online science program (Skatssoon 2004), Christidis said that the suggestion that songbirds originated in Australia had been considered ‘ludicrous’ earlier when presented by Australian researchers because, as most believed, Australia did not have that many birds relative to the rest of the world and so it could hardly be central to avian evolution. When Christides and colleagues first presented their results in the 1980s, they were ‘laughed at’ by their northern hemisphere colleagues. ‘Up until the last four or five years it's always been thought that the passerine birds originated in the northern hemisphere and spread south and that's been the gospel for the last 200 years,’ Christides was quoted as saying (Skatssoon 2004).

There was another major finding in 1997, showing conclusively that the worldwide mass-extinction event of 65 million years ago that had wiped out dinosaurs completely, did not end bird life. Indeed, Cooper and Penny (1997) found evidence for a mass survival of birds of at least 22 lineages, suggesting diversification already during the Cretaceous period 141–65 million years ago (Cooper and Penny 1997). Hence, according to this latest understanding, modern lineages did not arise after the mass extinction event but well before it, and knowledge of this then made it imperative to know when and in what sequence the various continents and land masses separated and which living cargo they took with them and which species evolved locally only after the supercontinent split apart.

Because of better technologies and new methods for measurements in the last 15–20 years, all these fields of research just about co-timed their new discoveries in such a manner that they could inform each other, leading to a virtual explosion of publications and new findings in the last 10 years. The very first and significant fossil find in Australia was the discovery by Boles of a songbird fossil carbon-dated as being about 54 million years old (Boles 1995). It is the oldest songbird fossil ever found. The next earliest to it is a recent find in Europe, dated to about 30 million years ago (Mayr and Manegold 2004). Clarke et al. (2005) reported a fossil find in Antarctica that represented the first Cretaceous fossil definitively placed within the extant bird radiation. It was a new species named Vegavis iaai and identified as belonging to Anseriformes (waterfowl) and closely related to Anatidae, which include true ducks. They inferred and concluded that at least relatives of ducks, chickens and ratite birds were living at the same time as non-avian dinosaurs (Clarke et al. 2005). Knowing now that waterfowl and ratites, of which the emu is a descendant (Fig. 1.1), belonged to very old lineages derived from the Australian part of Gondwanaland before separation from Antarctica allows us to trace the evolution of lineages not only along genetic and species lines but also in terms of the evolution of behaviour (to be dealt with in the next chapters).

In 2013, a fossil find of avian footprints discovered among the fossil-rich cliffs of Dinosaur Cove on the coast of southern Victoria caused another media stir (Sci-News.com 2013; Gannon 2013). The researchers think the tracks belonged to a species about the size of a great egret or a small heron (Martin et al. 2014). The find was identified as being about 105 million years old, placing it in the Early Cretaceous period and making this the oldest avian footprints ever found in the world (Fig. 1.2). This places the evolution of birds not merely well within the Cretaceous period but even towards the very beginning of this period.

A further landmark for avian evolution came from genome sequencing. By the end of 2013, the genomes of about 50 mammalian species had been sequenced while those of just seven bird species had been determined. The first was the chicken (Hillier et al. 2004), the second the zebra finch (Warren et al. 2010), followed by the turkey (Dalloul et al. 2010) and, among others, also the peregrine and saker falcons (Wang et al. 2013). In 2014, the budgerigar sequencing was published (Ganapathy et al. 2014) and some impressive genomics comparisons in birds were undertaken covering sequencing of a further 41 bird species allowing new and elucidating comments relevant to taxonomy (Zhang et al. 2014; Jarvis et al. 2014) and brain evolution, specifically with evolution of song and language in mind (Pfennig et al. 2014). No doubt, as a result of these substantial and new analyses, the next decade will bring further insights and new perspectives on avian evolution, diversification and radiation and a whole host of new information. They may even help elucidate how and when certain brain structures appeared in songbirds or even in specific species, such as the cockatoos, that have particularly large brains. We now have the means to probe the links between genes, brain, behaviour, environment and evolution. Indeed, such research has already started (Clayton et al. 2009).

Fig. 1.1. The emu derives from one of the oldest lineages of birds. It is particularly significant as one of the animals on the official crest of Australia. Emus (like other ratites) are unusual in that the male collects and broods the eggs of several females and protects the hatchlings until they can fend for themselves. Indeed, it is a complete role reversal. Females also initiate courtship.

Fig. 1.2. The oldest footprints of a bird (105 million years old) with the feet of an extant species superimposed. Very little change in the design of feet is apparent. The researchers regard the smudges on the left foot as an indication that the bird was just soft-landing from flight. This tantalising thought hints at the possibility that these early modern birds were perhaps not just gliding but had already acquired flight. The left footprint is not unlike that of a lyrebird. (Adapted from lifescience.com 25 Oct. 2013, and sci-news.com and Emory Health Sciences 28 Oct. 2013 online, www.sciencedaily.com)

At least the debate about the local origin of songbirds and many other orders seems to have been laid to rest, but it is worth remembering that this occurred as recently as 2004 and there are many unanswered taxonomical questions yet to resolve. We may well find, also in view of the results of comparative genomics, that some Australian avian species may still be reassigned to a different family or may become their own family in the near future (Christidis and Norman 2010). Investigations into the evolutionary history of birds are aided by better techniques, spectacular new findings and by more data points over many years of a lively taxonomy and paleontological culture in Australia. To this day, native Australian birds are being reassigned and renamed taxonomically (Brown et al. 2008). Moreover, species are still being discovered, mostly at the recent and extremely productive fossil site of Riversleigh in north-western Queensland such as a new parrot, stork, swiftlet and gallinule from the Tertiary to the Miocene (Boles 1993, 2001, 2005a, b, c).

So far confirmed is that, among non-songbirds, ratites, chicken, ducks, pigeons and parrots evolved in that part of Gondwana that includes present-day Australia and New Zealand. And then there are the perching birds, of which there are nearly 5800 species now, constituting 60% of all birds worldwide. Previous genetic studies had already supported the hypothesis that honeyeaters are an ancient radiation within Australasia (Sibley and Ahlquist 1985, 1990; Christidis and Schodde 1991). The earliest lineages to which lyrebirds and scrub-birds, treecreepers, bowerbirds and catbirds belong are thought to have evolved 53–45 million years ago. The next were the bristlebirds, pardalotes, fairy-wrens and scrubwrens about 35 million years ago. As far as we know, thereafter followed Corvida and Passerida. Core Corvoidea include the Australasian centred fantails, birds of paradise, whistlers, magpies, butcherbirds, currawongs, woodswallows, flycatchers, cuckoo-shrikes, orioles and crows. They seem to have evolved about 20 million years ago. By that time, the scleromorphous woodlands were already well established in Australia and increasing aridity and warming, and possibly also deficient soil conditions, low in calcium and nitrogen, changed the flora and encouraged the diversification of scleromorphous woodlands (Groves 1994). It has been argued that the spread of open woodlands and grasslands fostered the existence and spread of Australia’s giant herbivorous ground birds, such as the dromornithids, also called Mihirungs (Murray and Vickers-Rich 2004). Paleoclimate details of the last 250 000 or so years suggest some complex patterns of glacial and interglacial climate shifts with weakening northern monsoon rains. Rainforests receded; the land dried further and vast grasslands spread. The changes harmed some species, specifically the megafauna that became largely extinct, including the Mihirungs (Murray and Vickers-Rich 2004), but it benefited others. For instance, the spread of the family Artamidae and Cracticus (magpies and butcherbirds and allies) has been seen as tied to climatic changes and vegetation type (Kearns et al. 2011, 2013). This information gleaned from the paleontological literature (Christidis and Norman 2010) is convincing evidence enough for me to consider Australia and birds as belonging together and as inextricably intertwined. It is a question what the role of climate changes, innovation and cooperation might have had in them surviving and thriving.

Shape of Australia after break-off from Gondwana and bird life

The date of Australia’s final breaking off from the remainder of Gondwana and the precise shape of Australia as a landmass at the time of its breakaway seem to be relatively uncertain. Around 50 million years ago, well after the mass extinction, the shape of Australia is depicted as something very different in various publications. The Australian continent was nothing like the shape it is today and, to my surprise, I found little agreement as to which part of the continent was, at any one time in its paleogeographic past, really part of the landmass and which was submerged or formed islands. It is very clear, however, that in the Cretaceous period (i.e. in the millions of years when modern birds first evolved) mainland Australia was not one island and not a unified landmass (although it had the potential to be so depending on sea levels), but a myriad of islands because of rising sea levels (Fig. 1.3). Sources seem to agree that rising sea levels caused the large flat part of inland Australia to flood, allowing the sea to invade or even divide eastern and western Australia for probably tens of millions of years. These periods happen to roughly coincide with the now suspected period of evolution of modern bird lineages. Even at times of dominant landmasses, there were two large landmasses that were separated by substantial bodies of water, oceans that were unbroken by land from the north right down to Antarctica at the very time when birds are thought to have evolved (although it is not clear whether some parts of the southern end of Australia were submerged or not). Some publications for the general reader draw maps that are completely land while others draw contours that suggest that the continent was partly split into east and west. The myth of an inland sea may have arisen partly out of the knowledge that sea creatures were found in what is now central Australia and can be seen displayed in Coober Pedy. It is hard to imagine that the land on which Coober Pedy was built – now the opal-mining centre of Australia and very much part of dry and hot inland Australia – was part of the ocean floor 120 million years ago and beyond. If part of the continent had consisted of many islands at the time when modern birds first evolved, this might well be of major significance. We know that oceanic islands drive divergence and speciation, but also have a potential role as repositories of ancestral diversity (Aleixandre et al. 2013).

Fig. 1.3. Australia 110 million years ago (thick black outline). The continent is far from being one landmass – with present-day Australia shown in white. This ‘inland’ sea is called the Eromanga Sea. It has yielded rich fossil finds of sea mammals. (Redrawn and simplified from Laseron 1984.)

Australia, at least for possibly a few crucial tens of millions of years, might have been a thousand islands, not one landmass in which species were readily able to criss-cross the continent. Many islands foster speciation and are said to have had an influence on brain evolution as well (Amiel et al. 2011). And much later, when Australia became one landmass (due to substantial falls in sea levels) and took on a shape similar to that of today, it then sported an appendage that was part of its tectonic plate: namely a land bridge to Papua New Guinea that spanned hundreds of kilometres and created an easy passage for birds to get to South-East Asia and for Papuan species to cross over to Australia. The extraordinary outcome is that the Australian landmass now has different ages in terms of emergence from the water – some areas in Queensland and in Western Australia have always been land but many others have a more recent history.

One of the starkest reminders of the ancient, but variously exposed, parts of the Australian continent are the unique sites in South Australia revealing Precambrian soft-bodied Ediacara Biota, dating back over 500 million years and showing so far the very first evidence worldwide of the emergence of mobile life forms (Gehling and Droser 2012). The fossils found in South Australia were once part of the sea floor. They now give us the first glimpse of organisms that became the template for all viable life forms from invertebrates to humans (Peterson et al. 2008). There can be nothing more ancient in a continent than such finds and these are on Australian soil and part of the patchwork of the current continental shape and composition that may have changed every so often and in significant ways: from land back to sea and back to land. This, as much or more so than even climate change, might have helped shape Australia’s bird life, and all of its other flora and fauna.

In summary, the current shape of Australia is not what it was at the time birds evolved due to: (a) changing sea levels separating parts of Australia from one another; (b) an important land bridge with Papua New Guinea, at least for some time; and (c) a receding coastline. Modern Australia, as a continent, is a patchwork, a quilt of parts that became exposed to become land at various times in prehistory and these phenomena present challenges when attempting to determine the biogeographical patterns of dispersal and diversification in birds (Jønsson and Fjeldså 2006; Schodde 2005b; Kearns et al. 2011).

It is very exciting to think that many passerine birds found along the east coast of Australia, such as lyrebirds, bowerbirds, treecreepers and honeyeaters, are living descendants of tens of millions of years of evolution, and they are not the only ones.

There are places in Australia where one knows one walks on millions of years of natural history, such as the extraordinary fossil sites of Riversleigh, Winton and Dinosaur Cove in southern Victoria, mentioned above, and other important sites that have yielded discoveries of remnants of bird bones. In addition, there are extant birds in special areas in the current shape of the Australian landmass that are both informative and revealing about the very special conditions of the Australian continent.

One of these special places, researched in detail by teams from Australian National University, is the Cape York Peninsula. Heinsohn and Cermak wrote that it had its own ornithological story to tell about the evolutionary ecology of birds of national and international importance. They wrote in their introduction:

The wildlife of Cape York Peninsula comprises a fascinating mix of ancient Australian species together with many recent arrivals from New Guinea and South-East Asia. This is because the tip of Cape York is only separated from New Guinea by a narrow and shallow channel of water, Torres Strait, and in the not-so-distant past the two landmasses have been joined by massive land bridges whenever sea levels have been lower. These bridges extended the area of land considerably and provided vast tracts of habitat, including entire river systems, lakes, swamps, woodlands, heaths and forests linking the wildlife of the two regions. The birds of CYP have an important story to tell because of their diverse evolutionary origins, and because they vary greatly in their mobility from sedentary species to long distance migrants. This makes their present day distribution and movements unusually informative for understanding our evolutionary past, including our original Gondwanan heritage, further evolution in isolation, and eventual re-connection with the rest of the world (Heinsohn and Cermak 2008).

The world has had good reason to think about climate change and changing sea levels. None is more acute than in Australia, already the driest continent and one that has been affected by changing sea levels in one way or another over millions of years. There is no writer on the evolution of bird life in Australia who is not keenly aware of the role of changes of sea-levels, climate and the geology itself as major driving forces in the diversification (meaning both speciation and extinction) of birds in the Australo-Papuan region (Kearns et al. 2013). Research in some environments, especially in the sea and the Great Barrier Reef