SOCIAL HIERARCHIES IN VERY YOUNG CHICKS

1. Three behavioural tests involving social competition were used to determine rank orders in groups of 8 male chicks aged between 4 and 18 days posthatching. 2. The group structure was found to consist of one or two dominant animals which consistently held a position at the top of the rank order, with a more flexible order beneath this. 3. Compared to the top-ranking birds, the middle-and lower-ranking birds showed more variability in their ranking positions across the behavioural tests and the testing periods. 4. Treatment of the lowest ranking individual in each group with testosterone led to this individual's rise in the rank order, most often to the top rank.