Thorleif Schjelderup-Ebbe

Thorleif Schjelderup-Ebbe (12 November 1894 in Kristiania – 8 June 1976 in Oslo) was a Norwegian zoologist and comparative psychologist. He was the first person to describe a pecking order of hens. Thorleif Schjelderup-Ebbe was at the age of 19, in 1913, the first to describe a pecking order of hens. He based findings on an interest in observing chickens at a farm where he spend his summer holidays. The dominance hierarchy of chickens and other birds that he studied led him to the observation that hens had an established social order determining who dared to peck whom in a fight. This order was, Schjelderup-Ebbe concluded, not necessarily dependent on the strength or age of the hens, and not necessarily a strict ranking as he even observed triangles of dominance. Schjelderup-Ebbe studied for a Ph.D. in Germany, tried to present his thesis in Oslo, but was rejected. He was the son of sculptors Axel Emil Ebbe (1868–1941) and Menga Schjelderup (1871–1945). He was married to Torbjørg Brekke. Their son was Dag Schjelderup-Ebbe, a musicologist, composer, music critic and biographer. Hønsenes stemme.