Deaths on December 21

Nikolaas Tinbergen, Dutch-English ethologist and ornithologist, Nobel Prize laureate (b. 1907)

Nikolaas "Niko" Tinbergen (; Dutch: [ˈnikoːlaːs ˈnikoː ˈtɪnbɛrɣən]; 15 April 1907 – 21 December 1988) was a Dutch biologist and ornithologist who shared the 1973 Nobel Prize in Physiology or Medicine with Karl von Frisch and Konrad Lorenz for their discoveries concerning organization and elicitation of individual and social behavior patterns in animals. He is regarded as one of the founders of modern ethology, the study of animal behavior.

In 1951, he published The Study of Instinct, an influential book on animal behaviour.

In the 1960s, he collaborated with filmmaker Hugh Falkus on a series of wildlife films, including The Riddle of the Rook (1972) and Signals for Survival (1969), which won the Italia prize in that year and the American blue ribbon in 1971.