organ; (2) evaluation of the "phenomena of behaviour and physiology" in relation to the natural environments; and (3) relation of the ecology of plant life to that of animal life. In Gordon Hewitt's 1921 book The Conservation of the Wildlife of Canada, Elton noticed the Canadian lynx and snowshoe hare population cycles, and developed greater understanding of population fluctuations in Arctic vertebrates with the Hudson's Bay Company. In 1932, Elton established the Bureau of Animal Population at Oxford, which became a centre for collecting data on fluctuations in animal populations. In the same year, the Journal of Animal Ecology was founded, with Elton as its first editor. In 1936, he was appointed reader in animal ecology at Oxford University, and Corpus Christi College elected him a senior research fellow. During the Second World War, the Bureau of Animal Population was entrusted by the Agricultural Research Council to find efficient methods for controlling rats, mice and rabbits. After the Second World War, Elton started a 20-year survey of animals and their interrelationships on Oxford University's Wytham estate, covering those in meadows, woods and water. After his retirement, he did some studies in tropical America. Elton's great interest in nature conservation and problems in management of nature reserves led him to be instrumental in establishing the Nature Conservancy Council in 1949. He was elected Fellow of the Royal Society in 1953 and received the society's Darwin Medal in 1970. Intellectual heritage In 1927, Elton published his classic Animal Ecology, outlining the principles behind ecological studies of animal behaviour and life history, such as food chains, size of food items, ecological niche, and the concept of a pyramid of numbers to represent the structure of an ecosystem in terms of feeding relationships. There he also introduced ideas such as the food cycle, the connection between various parts of the ecosystem, and the concept of food pyramid and trophic levels. He also discussed how ecosystems are organized and ordered, in what later became the foundation of the ecosystem concept. Elton was the first to discuss the ecological significance of population cycles. He also described how predators had an influence on prey, and so on generating cycles. In later works on the niche theory, Elton's definition – the Eltonian niche – in terms of functional attributes of organisms (or its position in the trophic web), has been viewed by some authors as opposed to Joseph