Stacks Image 1151
Copyright © John Smith, All Rights Reserved.

Scientific name: Pygoscelis papua

This is the most northern penguin of this genus and also, in many other respects, the odd one out. In contrast to Chinstrap and Adelie penguins, for example, some Gentoo penguins can be found around their breeding colonies all year round and they forage much closer inshore than the other two Pygoscelis species.

Identification

Stacks Image 2905
76-81 cm. Gentoo penguins are characterised by a white patch around and behind the eye that joins on the crown. The orange-red lower mandible is also a distinct feature. Two subspecies are recognised, a larger nominate form in the sub-Antarctic and a smaller, but otherwise similar, subspecies (ellsworthii) on the Antarctic Peninsula. Juveniles are very similar to adults, but the white eye-patch is not connected to their white eye-rings until they moult at an age of 14 months.

Distribution

Mainly in the sub-Antarctic, but extending to the Antarctic Peninsula. Breeds on Staten, Falkland, South Georgia, South Sandwich, South Orkney, South Shetland, the Antarctic Peninsula, Marion, Prince Edward, Crozet, Kerguelen, Heard, and Macquarie Islands. There is some evidence that the size of colonies depend on the local width of the continental shelf, i.e. the available inshore foraging area.

Habitat

Colonies are usually smaller than those of their congeners and are less densely packed. In the sub-Antarctic the nests are often found amongst tussocks, on the Antarctic Peninsula they nest on ice-free areas and beaches.

Breeding

Stacks Image 2935
At some colonies, birds are present year-round. Numbers in colonies increase prior to breeding. Birds go to sea daily before laying, albeit females may fast for about 5 days before laying the first egg. Clutch size is normally two with a laying interval of 3.4 days. Laying season is extended in northern breeding localities such as Marion and Crozet Islands (June to October/November) – where it is one of the few penguins to lay replacement clutches – compared to much more synchronous breeding at southern locations (October to November) such as South Georgia and the South Shetland Islands, where most nests are initiated within two weeks. Many females go to sea for 1-2 days between laying the two eggs. Incubation shifts are typically about 1 day at southern localities but may average 2-3 days at northern sites like Crozet. Incubation periods are 37 days for first eggs and 35 days for second eggs. Crèching occurs at 25-30 days of age. Fledging occurs at 80-105 days, but uniquely among penguins, fledged chicks return to the colony to be fed by parents for a further 5-50 days.

Diet

Dietary composition varies between season and locations but generally crustaceans, in particular krill (euphausiids), constitute the dominant prey item in the southern part of the range, whereas benthic fish are more commonly caught in lower latitudes. Cephalopods play only a minor role.

Migration and vagrancy

Stacks Image 2965
Gentoo penguins can be found near their colonies all year round unless ice prevents access – as it can in the southern parts of their range. Nevertheless, vagrants have been found as far north as 43°S on the Argentinean coast as well as in Australia and New Zealand.

Conservation and status

IUCN category: Lower Risk. Stable, not globally threatened. About 317,000 pairs.