The ontogeny of yellow-eyed penguin (Megadyptes antipodes) chick behaviour follows the order of development determined by Nice (1962) for several species of birds, and by Spurr (1975) for the Adélie penguin (Pygoscelis adeliae). Feeding and comfort behaviours are the first to develop, followed by locomotion and aggressive behaviour.
Active solicitation of food may occur at one day of age. Chicks initially use non-visual cues to mediate begging. After their eyes open on the third or fourth day there is an increase in the use of visual stimuli, and begging occurs most often following adult nest relief. Sibling rivalry is not intense, occurring least during feeding, and in general both chicks are fed at each session.
The chicks are brooded for the first 21–25 days. At sparsely vegetated nest sites overheating may occur after 21 days and down-covered chicks will seek shade and pant in hot weather.
Throughout the 6–7 weeks of the guard phase there is a decrease in the amount of time spent resting in a prone posture, and an increase in exploratory, locomotory behaviour. During the post-guard phase, and until fledging and independence at 15 weeks after hatching, chicks may wander up to 20 m from the nest bowl during exploration, shade-seeking and feeding.
Adults feed only their own chicks, and chicks appear to beg only from their parents. Dense vegetation and long distances between nests tend to restrict contact between adults and chicks from neighbouring nests, and prevent the formation of large chick crèches.