Emperor penguin (Aptenodytes forsteri) with its chick. The chick is vocalising. It uses a frequency-modulated whistle when asking for food from its parents. These are the only penguins to breed during the Antarctic winter. Congregating at colonial nesting areas inland, each pair produces a single egg, which the males incubate on their feet, surviving the extreme cold by huddling in large groups. Males fast during the two-month incubation period and lose almost half their body mass by the end. After the egg hatches in around mid-July, the male and female take it in turns to shelter the chick and feed it with regurgitated fish following foraging at sea. The chicks acquire their juvenile plumage in around November. Photographed in October, in Antarctica.