The breeding season of the Adélie penguin is short and closely synchronised to the Antarctic summer months of October to April (3) (5). The male arrives at the breeding ground first, and begins to build a nest out of small stones, before the female arrives a few days later (4) (7). Following a brief courtship of flipper waving and vocal displays, the pair complete the nest (3) (4), and the female will then lay a clutch of 2 eggs which are incubated by both adults for around 35 days (5) (6). The eggs hatch in early to late December (3), depending on latitude, and brooding of the new chicks is shared alternately by the two adults, allowing the other to feed at sea (5). After 3 weeks, the chicks gather in a small group of 3 to 20 individuals, known as a crèche, before fledging at around 2 months old (4) (5). Until this point, young Adélie penguin chicks at nest sites are very vulnerable, especially to predation by giant petrels and skuas (5). Gathering in a crèche helps protect the young chicks from predation and adverse weather, enabling both adults to forage simultaneously (3) (7). The Adélie penguin displays ‘natal philopatry’ (2) (4), meaning that, under normal circumstances, when breeding begins at between three to five years of age, the bird will often return to the same colony in which it was born (7).
The Adélie penguin feeds mainly on krill and small fish, although the diet also includes amphipods and cephalopods (5) (6). During the breeding season, foraging occurs in coastal waters close to breeding colonies, although migration further afield during the winter months is common (4) (6). The Adélie penguin is capable of diving up to 175 metres to forage for food (2) (5) (7), and is able to reach speeds underwater of 15 kilometres per hour (4). Less elegant on land than in the water, the Adélie penguin is nimble and able to walk long distances at speeds that average 2.5 kilometres per hour; when travelling across snowy terrain, it can conserve energy by sliding across the snow on its front, using its wings and feet to propel itself forwards (2) (4).