Rockhopper penguin  (Eudyptes chrysocome)

Penguins are gregarious, and rockhopper penguins breed in large colonies that may be composed of over a hundred thousand nests (2). They are monogamous, and pairs usually return to the same nest on consecutive years (2). Eggs are laid in November, clutch size is generally 2 eggs of unequal size, with only the chick from the larger egg usually surviving to maturity. Incubation takes around 33 days and both parents will take it in turns to sit on the eggs for extended periods of a time whilst their partner forages for food; penguins have a bare patch of skin on the lower abdomen (known as a 'brood pouch') that allows greater heat transfer to the eggs (2). Once the chicks have hatched the male will remain to brood them for the first 25 days, whilst the female regularly brings food back to the nest (2). After this time, the chicks are able to leave the nest and are left in small groups known as 'crèches' whilst their parents forage (2).

Penguins have a waterproof coat that is maintained by constant grooming; this helps to flatten the feathers and to spread a waxy substance that is secreted just below the tail. Grooming is also an important social bond between pairs (2). Once a year however, the coat must be replaced; this annual moult takes around 25 days and occurs roughly a month after the completion of breeding. Prior to this imposed fasting period, adults spend time at sea building up fat reserves (2). After moulting, the winter months are spent at sea before returning to shore to breed the following spring. The diet of the rockhopper penguin is composed of a variety of oceanic species such as crustaceans, squid, octopus and fish (3). Groups may often feed together and dives may be to depths of up to 100 metres (2).