Magpie goose

The magpie (or pied) goose (Anseras semipalmata), is found in southern New Guinea and northern Australia. It is unusual in that it counts as a “living fossil”, being the only surviving member of the Anseranatidae family. It is therefore only distantly related to the 150 species of ducks, geese and swans that belong to the Anatidae family.

Appearance

The magpie goose has a typically goose-shaped body and is about 85 centimetres (34 inches) in length, which makes it one of the larger species of goose. Females are slightly smaller than males, at around 75 centimetres (30 inches). Male adult birds weigh nearly 3 kilos (6 pounds) and females just over 2 kilos (4.5 pounds).

The name “magpie goose” comes from the plumage which is white except for the head, neck, wings, rump and tail, which are black. Another name for the bird is “semipalmated goose” (likewise the Latin name) which refers to the fact that the long-toed feet are only partially webbed. The legs are bright yellow to orange, and the bill is yellow with a lighter tip, which is hooked. There is an area of reddish bare skin on the face, extending to behind the eye. There is a pronounced bony crown to the head.

The flight feathers only moult gradually, so there is no period during which the magpie goose is unable to fly.

Apart from the variations in size and weight noted above, the only easily observed difference between male and female magpie geese is that the head crown is more prominent in male birds.

Habitat

The magpie goose inhabits the floodplains of tropical rivers, usually near the coast, preferring grasslands and swampy areas. As mentioned above, it is native to tropical northern Australia but has been introduced to areas further south. It has occasionally been seen as far south as Tasmania.

The magpie goose is non-migratory, except when local conditions so dictate.

Behaviour

Magpie geese are gregarious at all times of the year, sometimes being found in flocks of up to 5,000 birds. They are infrequent swimmers, although they will feed from the water by up-ending. They often roost in trees and perch on floating logs.

The voice of the magpie goose is a loud honk.

Feeding

Magpie geese are vegetarian, their food consisting of plant matter taken either by grazing on land or up-ending in shallow water. They will eat seeds and bulbs as well as grasses (including rice crops) and aquatic plants.

Breeding

The breeding season is the wet season, which varies according to location. In the north of its range this is from February to April, whereas it is August to September further south. Individual pairs may breed at any time during this season, so a colony will consist of birds at many different levels of development. A pair would normally only produce a second clutch if the first had been lost, due to flooding for example.

The use of the word “pair” is misleading in the case of magpie geese, because a common arrangement is for a male goose to have two female partners, both of whom will lay in the same nest. The birds act as a strongly bonded group, although a lost member will soon be replaced.

All the group members build the nest, which is a mass of floating vegetation supported by growing plants. The site will probably be re-used in later seasons, although the nest will be built afresh.

The clutch can be any size up to around 16 eggs, these being laid by both females. All the group members share the incubation, which can alternate with shading the eggs from the sun if they get too hot. The male magpie goose tends to do most of the night incubation.

The eggs hatch at about 28 days, after which all the adult birds feed the chicks. This is done from the bill at first, and then food will be dropped in front of the chicks for them to pick up. Later, the adults will help the chicks to feed by, for example, rooting up bulbs for them and bending grass stalks down so that the seedheads can be reached.

Although the chicks fledge at about 11 weeks and are able to feed themselves from four months old at the latest, they will stay in the family group for much longer, only becoming fully independent when the next breeding season approaches. This is important from the aspect of protection from wild animals, as the rate of predation of eggs and young is high.

Conservation

The magpie goose is not thought to be in much danger as a species, being common in its breeding areas, although populations can fluctuate. It has been hunted in the past, which accounts for why its range is smaller than it once was, but that is not an issue within its present range. Future threats will be from loss of habitat or ecological disasters, should they occur.

However, there are captive and semi-captive populations of magpie geese in other parts of the world, including the Slimbridge Wetland Centre in Gloucestershire, England.

© John Welford