ADOPTION IN THE EMPEROR PENGUIN, APTENODYTES FORSTERI

Adoption in the emperor penguin was investigated to determine its rate of occurrence, biological causes and adaptive value. The study was carried out over 2 years in Terre Adelie (Antarctica). Adoption was relatively common: 351 cases were recorded out of 2068 chicks in the colony in 1993. Adoption occurred after kidnapping (53%, N=185) of a chick or with the brooding of a chick found wandering in the colony. Long-lasting adoptions were rare (2.3%) and most lasted only 0.5-10 days. Adopted chicks were 1-2 months old. Allofeeding occurred in a minimum 14.8% (N=52) of adoptions in 1993. Alloparents were failed breeders and non-breeding adults at the colony during the breeding cycle and were usually females. Chicks may benefit from being allofed and protected when winters are particularly harsh and more alloparents are available. However, alloparenting may be particularly explained by proximal causes, such as endocrinological mechanisms allowing the birds to be exploited by chicks soliciting food or brooding. (C) 1995 The Association for the Study of Animal Behaviour