The adaptive significance of crèches in the king penguin

Abstract

Creching behaviour in penguins is defined as the rearing of chicks by their own parents in large flocks called ‘creches’. Although several hypotheses have been proposed to account for the behaviour, the factors inducing chicks to aggregate remain relatively poorly understood, in particular for colonial seabirds. We studied creching behaviour in the king penguin, Aptenodytes patagonicus, by looking at the dynamics of creche formation and possible costs and benefits associated with this strategy. Creches increased in size but declined in number throughout the austral winter. They were located preferentially in the central parts of the colony. Lone chicks suffered the most aggression from unrelated adults, whereas chicks in a creche suffered the least. Chicks attacked by unrelated adults preferentially joined a creche. Adult aggression appeared to be a major factor inducing creching behaviour. Chicks at the periphery of a creche were more vigilant while sleeping, as measured by eye openings. Creches seemed to occasion intense competition among chicks for access to the centre. Chicks in poor condition were attacked and pushed to the periphery of the creche, where they were preyed on by giant petrels. During harsh weather conditions, chicks amalgamated into larger creches, tolerated lower interindividual distances and turned their backs to the wind and rain. Our results accord with the idea that creching behaviour in king penguins is a strategy that protects chicks from adult aggression, predation and severe weather.