Graeme Caughley studied the interactions between large mammalian herbivores and the environments they occupy. The pattern of population growth that can be predicted theoretically from such a relationship is both complex and variable. The animals will either erupt, crash, and then converge to a more stable density, or the population may oscillate indefinitely, the densities of plants and animals being locked into a stable limit cycle. He argued that the dynamics of mammalian herbivore populations are comprehensible only in terms of an interactive relationship between the herbivores and vegetation. He further argued that efficient management of such systems requires an understanding of the underlying mechanisms whereby the animals react to the plants and in turn the plants react dynamically to the effects of grazing.
He was best known for his contributions to the understanding of herbivore-vegetation dynamics in the New Zealand high country, the Himalayas, southern Africa and the semi-arid rangelands of Australia. His research was distinguished by rigorous design, execution and analysis, so that the conclusions had generality beyond the particular species studied. Since he chose topics that combined theoretical interest and practical application, he also influenced important management policies – deer populations in New Zealand, kangaroos in Australia and the conservation of large mammals in Africa and North America. He had, and continues to have, a major influence on thinking and practice in the field of vertebrate ecology and wildlife management throughout the world.
Graeme Caughley was born on 28 September 1937 at Wanganui, New Zealand, into an educated, professional family. He was the second of three children, and the only son, of John Norman Caughley and Thelma Caughley (née Keltie). His father was a Branch Manager of the Bank of New Zealand, in Wanganui until 1945, then in Palmerston North until 1955 and then at Eltham. He was also a good mathematician. His mother encouraged Graeme's curiosity and his father took him off on expeditions.
His paternal grandfather, James Caughley, migrated from Ireland at the turn of the century and was Headmaster of Takapau Primary School, Hawkes Bay from 1903 to 1936.1 He enjoyed children, loved teaching and had a wicked sense of humour, so that he had the ability to get fun out of the children, not to laugh at them but with them. As a boy Graeme knew his grandfather well and may have got his own dry sense of humour from him. Graeme's father was the eldest of four. The second son, James, was a psychologist with the British Army during the Second World War, and subsequently became Chief Psychologist in the Justice Department, Wellington. Graeme saw a lot of him while at university; they had dinner once a week and he was a mentor to Graeme. One of Graeme's two aunts, Nancy Caughley, taught Speech Therapy at the Christchurch Training College and was later a lecturer at the University of Tasmania, Hobart.
On his mother's side his grandfather, Hugh Keltie, was a watchmaker from Tasmania. He settled at Greytown in the Wairarapa, where he eventually had three shops. Graeme's grandmother died young and his mother was brought up by a stepmother, whom she did not like, so Graeme had little contact with his grandfather as he grew up.
He was not particularly close to his older sister, Jocelyn Ruth (Latta), born in 1932; but, despite the age difference of six years, he developed a close bond with his younger sister, Patricia Mary, born in 1943. He was her role model and encouraged her to go to university, where she did Honours in Political Science and a postgraduate diploma in international relations at the Hague. He said to her that the trouble with university was that it measured how well you knew the answers, but not how to ask the questions. Pat worked at the Commonwealth Secretariat in London, and later joined the New Zealand Ministry of Foreign Affairs for 22 years. She was posted to India in 1974–77 and visited Graeme in Nepal. In one of his early papers (8) Graeme acknowledged Pat's help. They remained close throughout their lives.
Graeme attended Drury Hill Primary School in Wanganui until the family moved to Palmerston North in 1945, when he went to Terrace End Primary and Intermediate School. At the age of eight he was collecting moths and butterflies and catching birds. And thinking about the meaning of fossil shells found high above the sea. In The Deer Wars (89) he describes his nascent scientific curiosity:
He had not heard of fossils and he was not happy with enigmas. He stood on solid ground, high up, far from the sea, holding a sea shell in his hands and trying to reconcile those things. The commonplace explanations would not fit and he abandoned them shortly to explore alternatives at first peculiar and then bizarre. Finally he isolated from the rest the only one that satisfied all the data: the sea once covered this hill. Excited, he picked his way down to the flat and ran across the paddocks to the house. His grandfather was a kindly man but he would not humour even a child to that extent. 'Nonsense,' he said firmly and then laughed to signal that he was not annoyed, that it was only a small thing. He did not forget that shell and he was surprised to discover a few years later that he had been right, not quite in the way he had envisaged, but near enough.
While not exceptional in class, Graeme had an unusual breadth of knowledge. At the age of 12, when at Palmerston North Boys High School, he challenged Crosbie Morrison, then a well-known radio broadcaster on natural history, on a question of classification of moths. Graeme thought Morrison was incorrect and, with his best friend, Martin Hyde, did a year's study on the matter and was able to refute him. Later, in about 1953, he was in the New Zealand national team for 'Quiz Kids' with Jonathan Hunt.
On leaving school Graeme joined the Department of Internal Affairs in February 1955 as a government hunter, based at Rotorua, shooting deer, pigs and goats. This year was a formative experience, which he describes in detail in The Deer Wars. In Rotorua he met Thane Riney, an American ecologist who had recently come to New Zealand to work on deer and goats for the New Zealand Forest Service. Riney gave a talk on his work and after it Graeme said to John Henderson, President of the Deer Stalkers' Association, 'do you mean that people can earn a living doing this sort of thing?' Graeme became a disciple of Riney's and two years later joined him as a field assistant, publishing with him on the home range of feral goats (2).
Graeme enrolled for a BSc at Victoria University College, Wellington, in 1956, where he had to support himself financially. In his first year he had free lodging at the Miramar Fire Station in exchange for being on call as a volunteer fireman living on the premises. Of this time he told an amusing episode against himself (Ian Parker in 143). Overwhelmed by urgency and excitement at his first fire, he charged into the burning house and amidst blinding, eye-watering smoke and flames found a person to rescue. That this man fought him off violently he put down to panic. After an epic struggle he got his victim across his shoulders in the approved fireman's lift and made for the exit. Bystanders were delighted when the diminutive Caughley shot out of the smoke with another fireman twice his size on his back. There is no record of any particular lecturers influencing his thinking and the only comment on his experience at university is that he was marked down for using regression analysis on results from a physiology project. He joined Riney in the New Zealand Forest Service in 1956 and continued his degree studies part-time, completing his degree at the end of 1959.
During the summer of 1958–59 Graeme went to Antarctica as a biologist with the New Zealand Antarctic Division, based at Scott Base. He worked on the Adelie penguin colonies around Ross I. and Beaufort I. and the Emperor penguin colony at Cape Crozier, publishing substantial papers on both species (6, 4), as well as notes on skuas (5) and seals (7). These early papers, written at the age of 22, already demonstrated some of the characteristics of his later investigations – questioning strongly-held beliefs, checking original sources and demonstrating a thorough knowledge of natural history. He revised down the estimates of mortality of Emperor penguin chicks at the Cape Crozier colony (4) from those of Edward Wilson, and he also questioned Wilson's assumption that chicks float out to sea on pack ice before they have shed their down, an idea that had been repeated many times and accepted as fact. He acknowledged the help of Dr Robert Falla, Director of the Dominion Museum, in the preparation of the penguin papers. Caughley Beach at Cape Bird, Ross Island was named after Graeme. It has been recognised as a Site of Special Interest by the International Committee on Antarctic Research and, like others, it was proclaimed under Australian legislation, the Antarctic Treaty (Environment Protection Act) 1980.2 There is a brief description of Caughley Beach in the Australian Gazette of 29November 1993, which states that it 'is the site of the most extensive stands of moss, algae and lichens in southern Victoria Land. The terrestrial ecosystem within the Site is the subject of long-term research.'
Graeme's BSc degree from the University of New Zealand (of which Victoria University College was at that time a part) was conferred in May 1960 by which time he had moved to the School of Biological Sciences in the University of Sydney to undertake research for the MSc under the supervision of Charles Birch and Harry Frith, Chief of the CSIRO Division of Wildlife Research. His topic was the comparative ecology of Red and Eastern Gray Kangaroos (Macropus rufus and M. giganteus) on the CSIRO sheep station, 'Gilruth Plains', near Charleville. The MSc was conferred in April 1963 and from it Graeme published papers on the social organization and daily activity (11), density and dispersion of the two species (12), and on sex ratios (13). These were the first papers to be published on social organization and activity of any species of kangaroo.
At the end of 1962 Graeme returned to the New Zealand Forest Service to begin a study on the population dynamics of alpine mammals, particularly the Himalayan Tahr (Hemitragus jemlahicus). [Note the correct spelling is tahr, but in New Zealand it is spelt thar]. The study developed out of work that Thane Riney had done in California on the eruption and spread of ungulate populations. Tahr had been liberated in the Mount Cook area of South Island in 1904–09 and Graeme chose the spread of Tahr in New Zealand as a good species with which to test Riney's ideas. In 1965 this work became the basis for his PhD from the University of Canterbury, awarded in 1967. His supervisors for this were Bernard Stonehouse and Euan Young but, as Young said,3 'Not that anyone actually supervised this work. His understanding of population processes even then was much superior to ours.'
Graeme developed his ideas about ungulate populations into major contributions in papers 22, 23, 24 and 28. Using new definitions of birth and death rates, he proposed a mathematical framework for analysing the dynamics of seasonally breeding populations. For example, in Paper 22 on mortality patterns in mammals he used his new data for Himalayan Tahr to develop a comprehensive examination of methods of obtaining life table data, and of the assumptions and biases in most analyses. In it he showed that the known relationship between mortality rate and age for humans also held for all mammalian species for which data were adequate. This new analysis established a single mortality pattern for all mammalian species, including humans, irrespective of the body size or life history of the species or whether they were wild or domestic.
Similarly, in Paper 24 on parameters for seasonally breeding populations he used data from a well-studied population of domestic sheep to show that the basic equations used in demography could not be used to cover all populations, especially those species with restricted annual breeding seasons. These two papers are regarded as classics in mammalian demography and, as Charles Krebs later said, 'he single-handedly put large mammal ecology into a theoretical framework'. Paper 22 was reprinted in 1970 (27) and 1982 (79) in the USA for student use.
Paper 28 on eruption of ungulate populations became widely known for two reasons. Using data from his own study of the increase of the Himalayan Tahr since its introduction to New Zealand, he showed that the build-up in species' populations after their introduction to new areas is essentially the same as eruptions in natural mammalian herbivore populations. The growth pattern does not follow a logistic curve as had previously been thought but is an eruption and crash followed by stabilization. Because this interpretation was at variance with a widely-quoted study on a population of deer on Kaibab Island, Canada, he re-examined that study and showed that the original observations had been overlaid by accretions and interpretations of later writers, including the doyen of American ecologists, Aldo Leopold; when these were exposed the original evidence was uninterpretable.
Graeme was now demonstrating his talent for picking key questions and presenting them in provocative but well-researched papers. Much later in his life he disclosed his philosophy about research in the preface to a book that he was planning to write, to be called The Kangaroo Game:
Let me describe myself to allow you, the reader, to gauge my motives and my view of the world. Confessions are not the best source of truth but they give clues, even if one must read between the lines. Socially I am inept. I go to considerable lengths to avoid meeting new people. I find it a strain. Charming I am not. Politically I am uncommitted.
I am good at research, not as good as I would like to be but somewhat better than average. Research is not quite the activity that most people think. It is a blood sport in which the opponents are other researchers. It must be the cleanest sport in the book because the ground rules, agreed to by the great majority of participants, ensure that in the long run the best win. Even in the short run not too many injustices occur. The ultimate high in research is not the discovery of a new fact – that you do almost once a week – but in writing a scientific publication that changes thinking. If you are good you might achieve that with every tenth paper. But when you do it you know that you have done it, even before anyone reads it, and then you sit back and say to yourself 'try to shoot that one down, you bastards.' When congratulated for the incredible insight displayed by 'your book' the correct response is 'which book'; or if you lobbed this mortar shell in the form of a paper you can practise 'Oh, that old thing' or 'Actually, I am not quite certain that I got it exactly right.' Research is a very serious business, it is the cutting edge of science, but it is also great fun.
You also need to know something about my attitude to killing animals. Take the extreme case, the killing of a large whale by means of an explosive harpoon. It is not pretty, and I think I would like myself better were I to view it as an aesthetic and moral outrage, but I do not. It is not important that you agree or disagree with this viewpoint. The importance lies in your realising that this is the way I am and in interpreting what I write in the light of that knowledge. I have no strong feeling for individual wild animals although paradoxically I cried when the family cat was run over. However I get very emotional about the suggestion that a population of wild animals should be exterminated. Hence I am a conservationist but not an animal-liberationist.
Charles Birch recognised some of these aspects of Graeme's character in 1979:4
If he has any irksome qualities they are a tendency to exaggerate for effect, to be a bit of a know all and to always be right. It is a sort of game playing in which points are being scored. In other words you do not always get a frank and open discussion with him if something he values is at stake, and he does have some very definite points of view and objectives. This does not basically make him a difficult person to work with. It does mean that on some issues one learns to take him with a grain of salt.
On completing his PhD Graeme undertook a series of consultancies as a wildlife biologist for the Food and Agriculture Organisation of the United Nations (FAO). This came about through Riney, who was now at FAO Rome. In March 1968 Graeme went to Nepal for a year to do a biological survey and to set up National Parks (26). During this time he made observations on the distribution of Tahr in its native habitat (34) and once again challenged old assumptions and showed how they were incorrect. All texts on Himalayan wildlife stated that Tahr live below the tree line, whereas in New Zealand they live exclusively above the tree line. From his own observations he confirmed that the same was true in Nepal and that all writers on Himalayan wildlife had quoted, directly or indirectly, from two nineteenth-century hunters who had collected male trophy heads below the tree line; in both New Zealand and Nepal lone males leave the breeding herd and descend into the forest but the main population live above the tree line.
In 1969 the FAO sent Graeme to Kenya to determine the accuracy of methods for assessing density of wild ungulates and later, at the invitation of the Iranian Government, he visited the Pamirs to estimate optimum sustained yield for Marco Polo sheep (Ovis poli). He also made a three-month trip to Afghanistan to investigate conservation status of endangered species (35). During these trips Graeme developed an interest in old coins. FAO consultants were paid part of their salary in local currency and, since it was difficult to exchange, he bought old Tibetan coins in Nepal. Later in Afghanistan, ancient Bactrian coins attracted his attention, as well as Greek tetradrachmas from the time of Alexander the Great. The interest in these coins continued and he built up a small collection by subsequent purchases.
At the conclusion of the consultancies, in 1969, he was awarded a Queen Elizabeth II Fellowship at the University of Sydney, and spent the next two years developing his theoretical approach to wildlife ecology. In 1971 he and Charles Birch, in a paper on rate of increase (43), showed that biologists studying the population dynamics of mammals were estimating the rate of increase incorrectly; they were using equations that were valid and widely used for insects but inappropriate for mammals. The logical fallacy in the common practice of calculating rate of increase from age distribution was indicated, and the appropriate methods of analysis were pointed out. The paper was subsequently reprinted as a 'classic' in Wildlife Population Ecology for student use (79). He also wrote the first draft of his book Analysis of Vertebrate Populations (62) but was then unable to interest a publisher in the manuscript; it languished for four years until accepted by Wiley in 1975. He also continued to do short consultancies for the FAO in Nepal, Afghanistan and Zambia.
During the Fellowship he met Judith Ada Badham, who was doing her PhD in ecology in the same School, and they were married in 1970. At the conclusion of the Fellowship in mid-1971, Graeme and Judy went to Zambia to complete a FAO project on elephant in the Luangwa Valley, begun by John Goddard, who had died when the project had eighteen months left to run. The aim of the project was multiple use for the Luangwa Valley – conservation, subsistence harvesting in wildlife management zones, agriculture and tourism – so the scientists involved were a very diverse group. The Caughleys worked and lived entirely within the national park in the centre of the Valley for the whole of their stay. Africa was good to them and they enjoyed the work. Judy described it as a wonderful, wonderful experience. Their son, Ian, was born there. Judy went through Goddard's diaries to get the data and analyse his aerial survey results, while Graeme continued the aerial surveys. He met a lot of people from Kenya and other countries doing aerial surveys of elephants and other large mammals – especially influential were Ian Parker and Michael Norton Griffiths. The most influential population ecologist was Richard Bell, who from his work in the Serengeti introduced Graeme to the field of African plant-herbivore relationships.
The fruit of this interaction was Graeme's refinement of analyses of aerial surveys (44, 49, 52) and the development of his ideas on the long-term interactions between elephant and the trees that provide it with food and shelter (56). He suggested that 'the elephant problem' – elephants knocking down forest faster than the forest regenerates – does not reflect the notion, as previously believed, that an equilibrium between forests and elephants has been displaced. The evidence indicated that elephants increase while thinning the forest and then decline to a low density that allows the forest to recover. Elephants then begin to recover and the cycle repeats. This he defined as a 'stable limit cycle' which may be very long. He estimated the length of the cycle in the Luangwa Valley to be in the order of 200 years, from the size distribution of Mopane trees, which showed a bimodal distribution suggesting an earlier period of low recruitment, and the age distribution of Baobab trees, which showed a unimodal peak at about 140 years. Since elephants browse young Baobabs the data suggested that a low density of elephants 140 years ago had allowed a cohort of Baobabs to become established and reach sufficient size to survive. The idea was put forward with characteristic verve and the paper aroused considerable interest in all African countries dealing with the elephant problem, and changed perspectives on management of the species.
Fourteen years later (130) Graeme examined this further by analysing the volume of ivory coming on to the world market since 1950, to determine the trend of the elephant populations from which it came. The data were consistent with a rapidly declining population. He deduced that few elephants would survive in East Africa outside high-security areas after 1995. The trend for Africa as a whole was similar but lagged about twenty years behind that of East Africa. This work was both clever and beautiful, but also written so tersely that it needed translation before it could be appreciated by all concerned.5 It showed that the ivory trade rather than habitat loss has been the main cause of decline in elephant populations and it influenced the decision to ban international traffic in ivory so as to conserve the species.
Early in 1973 the Caughleys returned to Australia and he took up an appointment as Lecturer in Ecology in the School of Biological Sciences at the University of Sydney. The next six years in Sydney were a very productive time for him, although Judy recalled that he was never really happy in the university environment. For someone accustomed to working in a team he found it difficult to accommodate to the individualism of the university. He enjoyed the lecturing but the aggressive competition to do the minimum of lecturing and get the best post-graduate students distressed him. Nevertheless, his few post-graduate students remember his influence warmly. Bill Magnusson (personal communication 1997) recalled how he became Graeme's PhD student in 1974:
Thin, wiry and not very academic looking, he was so intent on his work that he looked up distractedly when I knocked on his door. 'Dr Caughley, I am putting together a thesis project on the nesting ecology of salt water crocodiles and I was wondering if you'd look it over for me?' He pushed aside his papers and our talk lasted about half an hour. His experienced mind quickly picked out the good bits, discarded the bad, and suggested ways to prop up the weak aspects. He never asked who my supervisor was. At the end of our discussion I asked if he thought it a good thesis project. He paused and said sincerely, 'yes it's a good project.' As he turned back to his papers I said 'So you're willing to supervise my project?' He said without thinking 'Oh! – yes.' A few minutes later Graeme was in Gordon Grigg's office saying 'Who is that Magnusson character? I think he has just suckered me.' Whether or not it was an appropriate way to get a supervisor, the next day Graeme said 'Alright, I'll supervise your project but only if Gordon is a co-supervisor.'A year later, after Graeme had been into the field with Bill, he commented to a colleague that Bill seemed to be a good researcher, to which she replied 'Of course he's good!' He looked her in the eye and said 'If he's a good researcher, how did he get through our University system?'
Graeme met Robert May, then at the University of Sydney, and was attracted by his ideas on stable limit cycles, which Graeme developed in the elephant-plant system. At the same time Graeme was developing concepts of plant-herbivore systems, to which he had been introduced by Richard Bell, while he was in Zambia. May invited him to write the chapter on plant-herbivore interactions (54) for the book Theoretical Ecology that he was then editing for Blackwells. Caughley's chapter explored the theoretical relationships between a population and its resources in a number of plant-herbivore systems, ranging from simple through varying degrees of complexity, classified them into functional categories and indicated the expected dynamic behaviour of each. A close fit between observation and theory was shown.
In the same year (1976) he was invited to write on wildlife management and the dynamics of ungulate populations (55). At the time this essay was written, advances in wildlife management had not kept pace with those in other fields of population management, notably fisheries biology and economic entomology. The paper was an extended treatment of the relationship between population dynamics and population management using the ungulate-vegetation system for examples. Suggestions were given for estimating sustained yield and for managing an ungulate population to minimize damage to the vegetation. It was a powerful impetus to the development of a harvest theory for ungulates and had a profound influence on the management of large herbivores in the national parks of North America and world-wide.
In 1977 Caughley's book Analysis of Vertebrate Populations (62) was published by Wiley. It dealt largely with the problems of sampling, estimation and analysis and was an immediate success. It was recognised as the seminal work on the dynamics of vertebrate populations and how such populations may best be studied, and established him as the leading ungulate ecologist and one of the top five vertebrate ecologists in the world. Prior to the book's publication the ecologist wishing to be informed on vertebrate populations had to read a very large and scattered literature; it was awarded 'Book of the Year' by the American Wildlife Society and was translated into Russian (63). It is still the primary reference in the discipline and is still widely consulted.
Publication of the book brought lots more contacts and invitations to numerous conferences, especially in North America. Graeme wrote an amusing anecdote about one of these that he attended in 1978:6
When the proceedings are published and I find out what was said there, I may write about the scientific advances unveiled at the Elk Ecology and Management Conference at the University of Wyoming, 3–5 April 1978. The first inkling of disaster came when I was handed on arrival my schedule of 'extra-conference commitments.' The design (as we say in statistics) being exhaustive but non-overlapping. Into the interstices of this time frame was fitted a conference that began at 8am each day and continued indefinitely. By halfway through the second day I was suffering severe physiological stress. I gave a paper later that night and remember only that the projector kept going backwards. No-one else seemed to notice. The third day is something of a mystery but I can piece together parts of it from my meticulously kept notes, the standard of which fortunately remained constant throughout. That day, for instance, I 'lynched with Harry and Chuck who disgust elbows. Very stimulation.' The fourth day I do not understand but I can give a broad outline. I was no longer in Wyoming but in Colorado, having been driven across the border at high speed, two hours before a gentleman would be contemplating whether his eggs should be poached or fried. Apparently someone, sometime, had said, 'You must come down to Colorado State University' and presumably my reply, whatever it had been, was interpreted as agreement. I was ushered into what appeared to be the Wallace theatre and instructed to give a seminar in the direction of an already assembled crowd scene. Since I had nothing prepared I simply babbled for an hour and in the process apparently insulted, quite unintentionally, half the heavier wildlife managers stationed north of the Rio Grande. The ensuing discussion was lively. Subsequent events are telescoped in my memory but the factor common to all was continuous discussion. The groups of beady-eyed post-grads and staff changed, as did the seminar rooms in which these chats occurred, but otherwise it was total talk Americans are earnest, generous, likeable and organised. If you are none of these you are in for a rough time.
Certainly, in North America Graeme's provocative style was not always appreciated. His major contributions were to introduce the use of mathematical analysis of mammal populations, to explain what he was doing with great clarity and simplicity, and to re-examine the basic tenets of wildlife ecology to provide a critique of entrenched dogma. However, the field of wildlife management, which had begun in the 1930s in the US, was still dominated by the writings of Aldo Leopold (Game Management, Scribners, New York, 1933) and a somewhat slavish adherence to the ideas of that great American master. When Graeme began to challenge the sacred tenets he was resisted bitterly by some of the most senior people. However, younger biologists were attracted to Graeme's thinking and four of them came up with the idea of publishing his ideas under a pseudonym, in order to get around the antipathy for Graeme in North America. They were Richard Bell, Douglas Houston, Michael Norton-Griffiths and Tony Sinclair. Graeme suggested the name John Macnab from the John Buchan hero of that name. There were to be four papers, each author taking a particular concept and then the others commenting on the draft. Three papers were published, 'Wildlife management as scientific experimentation' (86), 'Carrying capacity and related slippery shibboleths' (100) and 'Does game cropping serve conservation? A re-examination of the African data' (137).
Graeme did not shy away from controversy in Africa either, as Brian Walker remembered. The complexity of plant species composition in grazed systems prevented, for a long time, the acceptance of his conclusions based on analyses of the one-herbivore–one-plant model. His analyses of the models in 1982 (80) provided a theoretical basis for the notion that the diversity of plant species has little effect on the dynamics of plant-herbivore systems, particularly with respect to the fluctuations and equilibrium densities of the herbivore. From this and other work in Africa and elsewhere he had developed strong and convincing arguments against over-managing 'natural ecosystems' and he became an ardent advocate of letting ecosystems follow their natural dynamics with minimum interference by managers. His views were diametrically opposed to those held by African wildlife biologists at the time and, in two workshops in South Africa in 1979 and 1982, dealing with management of African wildlife and the problem of culling in national parks, he provoked vigorous discussion by asking 'What is this thing called carrying capacity?' and 'What is this thing called overabundance?' In the first (72) he emphasised the difference between ecological carrying capacity and economic carrying capacity, about which much confusion then existed. In the second (90, 91), where he was a principal speaker, he did not spare feelings in attacking the contrary views. The outcome was a salutary experience for all and his work on carrying capacities had a major effect on the direction and outcome of those meetings for wildlife management in Africa.
In Australia Graeme Caughley was becoming recognised as the pre-eminent expert on kangaroo ecology and population dynamics. In the early 1970s animal welfare groups in the USA campaigned to have the trade in kangaroo products abolished, on the grounds of the danger they represented to the populations of red and grey kangaroos. Wildlife biologists realised that an accurate method of measuring the size of kangaroo populations was needed to resolve this dispute. Caughley applied his African experience to this problem and began to develop accurate methods of aerial census of kangaroo populations (61, 65, 67, 69).
In 1978 Graeme submitted his corpus of publications, entitled The Dynamics of Mammalian Populations, for the degree of DSc, which he received from the University of Sydney early in 1979. However, although now Reader in Ecology, he was still unsettled at Sydney. Harry Frith and Graeme were members of the Advisory Board of the New South Wales National Parks and Wildlife Service and at one meeting in 1978, Graeme muttered to Harry, 'Have you got any jobs in Canberra?' Harry replied 'Maybe'. At the next meeting Harry said 'Were you serious?' and Graeme said 'Yes'.
Graeme was appointed Senior Principal Research Scientist in the Division of Wildlife Research in September 1979 to head a programme on kangaroo ecology. His aims were to determine the distribution, density and dynamics of the three main species of kangaroo across Australia, to determine appropriate options for their management, and to elucidate the ecological operating rules of the arid and semi-arid grazing systems.
He continued to develop the aerial survey techniques begun at the University of Sydney. He developed a rigorous system of calibration and statistical treatment that has made it possible to make regular estimates of the numbers of free-ranging kangaroos across the vast areas of Australia (71, 76, 82, 83, 88, 93, 94, 99), their movements (101), and the distribution of other large animals (81, 98, 105). Since 1980 these aerial survey techniques have been routinely used by the fauna authorities of the Australian states for their respective kangaroo management programmes, and by Environment Australia as the basis for the Federal Government's export quota system each year. The accurate knowledge of trends in kangaroo populations across the continent has helped to counter opposition from Europe and the USA to culling and harvesting of kangaroos. In 1986 Graeme successfully negotiated with members of the European Parliament against a proposed ban on kangaroo imports.
In addition to the direct application of his work on kangaroos, he also attempted to get some general principles out of the distributions of the three large kangaroos in Australia. One paper (114) used a fairly orthodox approach and standard distribution data, to show that each species reacts independently to specific and differing climatic variables and that biological interaction between species is not important. A second (117) took a quite different tack, using much tighter data that included dynamics attributes as well as simple distribution, and ended up with generalized results about the factors determining the edge of a species' range.
In 1983 he and Charles Krebs explored the importance of body size in mammalian ecology (87). Ecologists studying mammalian population dynamics have tended to base generalizations, covering all species, on results from the kinds of animals that they have studied themselves. This new analysis suggested that the ecological and evolutionary relationships between mammals weighing more than 30 kg and the plants that they eat differ intrinsically from those of smaller mammals and their food, a concept independently arrived at by comparative physiologists.
However, Graeme's major project in CSIRO was a collaborative one with the New South Wales National Parks and Wildlife Service, begun under the leadership of Neil Shepherd in 1977, to examine the relationship between high kangaroo densities and vegetation in an arid-zone national park (Kinchega National Park). With Graeme's transfer, CSIRO was invited to join in and Graeme and Neil shared the leadership from 1980 to its completion in 1985. Its aims were altered to include interactions with weather, vegetation and other herbivores and it was run as a joint enterprise, combining staff of CSIRO Division of Wildlife Research and National Parks and Wildlife Service (Preface to 108). The scale of the project is indicated by the fact that 400 student volunteers contributed to it as well. At the time it was the largest and most comprehensive study of a complex plant-herbivore ecosystem ever attempted. Graeme designed the joint study so that its diverse sub-projects dove-tailed to produce a synthesis of the dynamics of this grazing system. Growth, offtake, species composition and standing biomass of vegetation were measured over 600 km2 at frequent intervals. Kangaroos were censused regularly over an area of 200 km2, necessitating some 500 hours of aerial survey. The project identified and quantified the relationships between weather, plant growth, and rate of increase of kangaroos; it showed that the ecological relationships within the system were very tight and interactions occurred with minimum lag, despite the massive environmental fluctuations. Carrying capacity was shown to be a function of the coefficient of variation of annual rainfall. Sustainable harvesting rates and management strategies were defined. The study, which provided the most detailed and integrated analysis to that time of any grazing system in the world, was published by Cambridge University Press as a monograph (108), with Caughley as senior editor, entitled Kangaroos: Their Ecology and Management in the Sheep Rangelands of Australia. In addition to the book, 31 papers were published from the study as well as nine theses (4 Honours, 1 MVSc, 2 MSc and 2 PhD).
Although Graeme lived in Australia from 1973, his links with New Zealand remained strong and in 1983 he wrote an unusual book, The Deer Wars: The Story of Deer in New Zealand, published by Heinemann (89). In it he analysed the problem of wildlife management simultaneously from several perspectives: history, ecology, evolution, hydrology, geology, sociology, politics and economics. The book was unusual for several reasons: it was not a treatise on the ecology of red deer and the history of deer in New Zealand, although there was a lot of that in it; it was not a text on the economics and politics of managing a wildlife resource, although one can learn much about that in its pages; and it was not an autobiography, although Graeme obviously wrote from first-hand knowledge and experience. The book is a splendid example of problem-solving, vigorous and free-flowing text that examines the complex interactions between wild mammals, their environment and the perceptions and interests concerning these animals held by different groups of people within society. Graeme took a particularly good example with which to examine the evolution of people's perceptions of a wild species and the way in which government policy responds to these perceptions. It is the merit of this book that, while it is about deer in New Zealand, it has lessons for the management of wildlife everywhere. The book aroused some controversy in New Zealand, especially from forestry people who felt the bite in his criticisms of the research and management of wild deer. The point was made that Caughley had been out of New Zealand for much of the time when perceptions of deer and their uses were changing and that his analysis of this period could be faulted.7 The deer stalkers' association, however, applauded the book8 and Graeme was invited to address their annual conference in 1985 (104). Biologists, conservationists and those interested in land use in New Zealand also applauded the book. Its influence was profound because it appeared just before the administration of native forests was moved from the New Zealand Forest Service to the Department of Conservation. Graeme was the keynote speaker at a two-day seminar on wildlife legislation in New Zealand in 1988 (118, 119).
Sometime about 1986 or 1987 Graeme began a project on Quaternary faunal extinctions, climate change and the dispersal of people. He wanted to apply dispersal ecology and regression analysis to human ecology in order to understand the early spread of mankind across Australia. He recognised that the settlement of New Zealand by Polynesians about 1,000 years ago would provide a rigorous model for the much harder task in Australia. In 1988 he examined the pattern of colonization of New Zealand by the Polynesians (115) and the interaction of the avian megafauna, the New Zealand flora and mankind. It produced results at variance with the current anthropological paradigm of rapid colonization by Maoris of all coastal regions of New Zealand, and a long association of moas and Maoris. Instead, he proposed that the first landfall was made on the Kaikoura coast of South Island about 1,000 years ago and colonization of both islands spread out from there at an accelerating rate, reaching 10km a year after 400 years, when colonization was complete. Secondly, variance stripping on the radiocarbon dates indicated that the average time that megafauna and people co-existed in any district was only about one century. The inference from this was that the human population grew and spread on the abundant food resource in much the same way as the introduced ungulates did several centuries later. This paper had an important effect on ethnography and archaeology in New Zealand and it demanded a new appraisal of the time of arrival and the pattern of spread of the Maori people through New Zealand.
In a subsequent paper in 1989 (123), presented at a symposium of the New Zealand Ecological Society in response to the previous paper, Caughley examined the history of the New Zealand biota over the last 7,000 years. He divided it into three phases. BC 5000 to AD 1000 was a period of comparative ecological stasis. That equilibrium was disrupted between AD 1000 and AD 1800 by the destruction of most of the New Zealand plant-herbivore systems, the co-evolutionary relationships between the plants and the vertebrate herbivores being decoupled by about AD 1400. The ecology of the moas was deduced from what data were available to show that their closest living ecological analogues are not birds but browsing mammals.
Regrettably, the rest of the project, addressing the interactions of people and megafauna in Australia, was not completed by the time of his death.
Graeme Caughley continued to undertake many overseas consultancies. In 1988–90 he went to Tanzania, China, Kenya, Nepal, Canada, Greenland and Zimbabwe.
In 1989 he was appointed to the Resource Assessment Commission, set up by Act of Parliament to advise the Australian Prime Minister on resource matters. The Forests and Forest Industries Inquiry was instituted in November 1989 and was charged with describing the forests of Australia, the adequacy of their conservation, the timber and timber products industries of Australia, and any conflict between them. Caughley was the Special Commissioner with expertise in matters environmental. His contributions to the modelling that forms the core of the enquiry provided a basis for interpreting such data as were available. During 1990 he read about 260 submissions, went on seven field inspections and attended public hearings in fifteen centres around Australia (135). From his analyses he recognised that the rate of timber cutting of native forests exceeded the rate of increase and was therefore unsustainable, in the same way as the harvesting of whales had been unsustainable some decades earlier. These conclusions were incorporated into the Interim Report (135), which was made available for comment. The forest industry objected to these conclusions and demanded that a forestry representative join the Commission and oversee the final version of Caughley's report. He objected to this condition and to what he saw as the obstructive and intransigent attitude of the forest interests. When it was upheld by the Chief Commissioner, Caughley resigned and left for Greenland and a study of Muskox. As he said in another context (123) but applicable to the Commission:
Ideologies can be applauded or ridiculed but they cannot be invalidated unless they are converted to hypotheses. Then there can be reasoned scholarly debate. It is precisely to avoid that possibility that ideologies are always framed in abstract terms... We must not change reality to fit ideology.
Certainly the Resource Assessment Commission was a stressful time for him, not least because smoking was forbidden during the hearings and, since he had to attend all of them, he decided to give up smoking for the duration of the Commission. Also, in 1990, he and Judy decided to go their separate ways.
In 1991, he took on another public task as Chair of the Review of Australian Research Council Funding in the field of Ecology (142).
Recognition by his scientific peers followed. In 1992 he was elected to fellowship of the Australian Academy of Science, and in 1993 he received the highest award bestowed by CSIRO, the Chairman's Medal. In 1994 he was also awarded the Peter Scott Medal by the International Union for the Conservation of Nature but sadly did not live to receive it.
Graeme's attitude to conservation is expressed in the quotation given earlier; he was concerned about survival of species but was indifferent to individual animals. Because of his experience, as revealed in The Deer Wars, he had an impartiality as to whether animals are killed, culled or conserved and this approach is probably essential for a person who is to develop rational management policies. In the last years of his life he turned his attention more to conservation issues and the management of declining populations and away from harvesting and sustained yield issues.
In 1990 he began a project to test experimentally the effect of various stressors on the viability of small populations and, at the same time, began to gather material for a re-examination of the theoretical bases of conservation biology and the factors determining population viability. A major review on the subject was sent to the Journal of Animal Ecology in April 1993. In the same month he learned that he had terminal cancer and could not expect to live long. He set himself the goal of seeing the review through the press and, if time allowed, writing a book on conservation biology. With characteristic vigour and courage he saw the review published (145), and he completed a book already begun with Tony Sinclair entitled Wildlife Management and Ecology (144), published by Blackwells in 1994. In the months between April and December, with his partner, Anne Gunn, he wrote most of an entirely new book, which even drew critically on papers published in 1993. The major portion of the book, entitled Conservation Biology in Theory and Practice, was completed at the time of Graeme's death at his home in Canberra on 16 February 1994. Anne Gunn completed the book during the next nine months and it was published by Blackwells in 1996 (146).
The review and the book that followed aroused considerable debate. In the review (145) Graeme recognised two threads in conservation thinking. These he termed the small-population paradigm, which deals with the effect of smallness on the persistence of a population, and the declining-population paradigm, which deals with the cause of smallness and its cure. His criticism of the small-population paradigm was that it treats an effect (smallness) as if it were a cause and attempts to answer a trivial question – how long will a population persist if nothing unusual happens? His contention was that much of the theoretical side of conservation biology has been directed to population genetics and modelling to determine minimum population size, all of which he saw as part of the small-population paradigm. The declining-population paradigm, by contrast, is short on theory and generalization, because the causes of decline are different for each species, but determining the causes of decline is relevant to most problems in conservation. He concluded that the declining-population paradigm urgently needed more theory and the small-population paradigm needed more practice. He appealed for an intermixing of the two, which might lead to a reduction in the rate at which species are going extinct.
The review provoked a round-table discussion at the next annual meeting of the Society for Conservation Biology at Fort Collins, Colorado in 1995 and that was the impetus for Hedrick et al.9 to challenge Caughley's distinction of two paradigms as over-simplistic and something that should not be perpetuated. They were especially exercised by his argument that theoretical models based on population genetics had not contributed to the rescue of any declining species, as this would give ammunition to hostile forces attempting to discredit conservation efforts. Young and Harcourt10 then came to Caughley's defence, as did Clinchy and Krebs,11 the latter daring to 'be brought before the Inquisition on charges of heresy' by taking Caughley's distinction further. They suggested that the two paradigms represent a wider dichotomy in conservation biology between laboratory-based research (the small-population paradigm) and field-based research (the declining-population paradigm). It is clear that, in his last paper, Graeme Caughley had once again lobbed one of his mortar shells at his favourite protagonists, his peers in ecology, and scored well!
The book (146) that was written hard on the heels of the review was an astonishing achievement, even without considering the conditions under which it was written. In a real sense it is a response to the appeal of the review, to provide conservation biology with a strong theoretical underpinning. This it does, and also offers a wealth of examples and practical solutions for the particular problems faced by species in decline. It is destined to be the handbook of first resort in conservation biology for years to come. While Graeme's mind is in it all, Anne Gunn played a huge part in the support she gave him through the last months of his life and in the hard task of completing it for publication. As his friend Ian Parker wrote in the front of the book, 'he was thinking originally to the end'.
After his untimely death at the peak of his intellectual powers, there was a move to create some fitting memorial to Graeme Caughley. The Graeme Caughley Travelling Fellowship was established through the joint auspices of the Australasian Wildlife Management Society, the CSIRO Division of Wildlife and Ecology and the Australian Academy of Science. Its purpose is to encourage exchange of ideas and knowledge about wildlife management, by travel grants to enable Australian and New Zealand ecologists to visit colleagues in other countries. The first two Caughley Fellows were David Choquenot, who travelled in Africa, and Jim Hone who travelled in Europe and North America.
In ecology Graeme Caughley led by setting high standards of research and integrity tempered by a delight in ecological relationships and a rapier wit. As mentioned earlier, The Deer Wars was partly autobiographical and the last words of that incomparable book sum up Graeme's philosophy of life:
The formative mythology of the New Zealanders is not easily dissected, and perhaps it should not be attempted because to dissect is to destroy. But some elements can be displayed without trauma: water on fern, breaking out of forest onto snow grass, a fist in the scrum, the lobbed shot that comes off, the flooded river that must be crossed, the piton that gives just a little, 'and the antlers in the hall, sings Harry'.
These I judge necessary and their absence as impoverishment. I am certainly growing no younger and maybe I missed the point somewhere along the way. But what do you judge as important?
This memoir was originally published in Historical Records of Australian Science, Vol.12, No.3, 1999. It was written by C.H. Tyndale Biscoe, School of Biological Sciences, Australian National University, Canberra, ACT.
For providing information and anecdotes about Graeme and leads to his correspondence I thank David Grice, Anne Gunn, Bill Magnusson, Roxanne Missingham, Steve Morton, Peter Shaughnessy, Tony Sinclair, Rodney Teakle, Brian Walker and Rosanne Walker. Pat Caughley and Judy Caughley were especially helpful in providing the background to Graeme's early life and research career. The notes used to prepare this Memoir and most of Graeme's papers have been deposited at the Australian Academy of Science. Other official files concerning his time in CSIRO are held in the Australian National Archives, Canberra.
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