Nikolaas (Niko) Tinbergen, one of the founding fathers of modern ethology, was born in The Hague on 15 April 1907. After secondary schooling in which he neglected the traditional academic subjects in favour of his sports and natural history interests, he spent a couple of months in the autumn of 1925 at the Rositten observatory in East Prussia which pioneered the scientific ringing of birds. This experience of biological fieldwork persuaded Tinbergen to enrol as a student at the University of Leiden where he specialised in zoology. In 1931 he was appointed 'assistent' in the Leiden Zoology Department and in 1932 he was awarded his PhD from Leiden for his homing studies on wasps of the genus Philanthus. Married in 1932 to Elizabeth Amelie Rutten, Tinbergen and his wife then spent two summers and a winter among the Anmagssalingmiut Eskimos of East Greenland studying the snow bunting, red-necked phalarope and husky. Returning to Leiden he taught experimental zoology and especially animal behaviour until 1949, by which time he was Professor and Head of Department. His career was interrupted during the Second World War when he was imprisoned as a hostage by the German occupation authorities.

During his time at Leiden Tinbergen developed laboratory work, in which the three-spined stickleback proved a particularly successful experimental animal, and field studies initiating projects on wasps, butterflies and hobbies at an annual camp which he organised for his students among the sandhills of Hulshorst. His work on the breeding behaviour of herring gulls also dates from this period and, like the stickleback research, became one of the classics of ethology. In 1936 Konrad Lorenz, who was later to share the Nobel Prize with Tinbergen and Karl von Frisch, visited Leiden. Lorenz and Tinbergen immediately recognised their common interests and Tinbergen spent the spring of 1937 working with Lorenz at the Lorenz family home at Altenberg, near Vienna. This association was to have the greatest importance for their science. In 1938 Tinbergen made his first attempt to introduce the ethological approach to animal behaviour studies to the English-speaking world on a visit to the USA. He pursued this mission with great dedication and success after the war.

As an essential step in this process Tinbergen resigned his professorship at Leiden in 1949 and accepted a less well paid and less prestigious lectureship in A. C. Hardy's department at Oxford, where he remained for the rest of his career. He was appointed Professor of Animal Behaviour in 1966 and retired in 1974. At Oxford he lectured with great success on animal behaviour to zoology and psychology students, and built up a research group that had a profound influence on the development of ethology round the world. In particular, his research focused on the adaptedness of behaviour. His work on the herring gull initiated in the Netherlands developed into comparative studies of many gull species. Tinbergen's most influential book The Study of Instinct, based on lectures given at the American Museum of Natural History in 1947, appeared in 1951 and Social Behaviour in Animals followed in 1953. In keeping with his aim of spreading the ethological message he made frequent visits abroad to attend conferences and also accepted the occasional one-term visiting professorship. Two of his best books were written for the educated layman, The herring gull's world (1953) and Curious naturalists (1958), and in the 1960s he devoted much effort to making scientific films. One of these, 'Signals for survival', made with Hugh Falkus, won the Italia prize for documentary television films.

In the 1960s Tinbergen became increasingly preoccupied with the implications of the ethological approach for man. One aspect of this was his support for the initiative of Hardy's successor, J. W. S. Pringle, to establish at Oxford a new honours course in "The Human Sciences". It is reflected also in the titles of his inaugural lecture as Professor of Animal Behaviour 'War and peace in animals and man' (1968), and of his Royal Society Croonian Lecture 'Functional ethology and the human sciences' (1972). Furthermore, Tinbergen was interested in science and society relationships and felt it was the duty of the scientist to draw attention to man's increasing disadaptation to his environment and to suggest ways in which he might be readapted. Tinbergen lectured on this topic on a number of occasions, but put aside a book on the subject unfinished to concentrate his energies in retirement on a more specific application of ethological methods to human behaviour. For over ten years Tinbergen and his wife collaborated on a study of the serious mental disorder childhood autism, publishing the results of their enquiry into its nature, ontogeny and treatment, 'Autistic' children - new hope for a cure, in 1983.

Tinbergen received many honours and awards in recognition of his contribution to ethology. In addition to the Nobel Prize for Physiology or Medicine (1973), he received the Swammerdam Medal, awarded only every ten years, and honorary degrees from Edinburgh and Leicester. He was elected to the Fellowship of the Royal Society (1962) and to national academies in the Netherlands, Germany and the USA. Tinbergen died in Oxford in 1988.