Oca gazza

Identificazione

Magpie geese are unmistakable birds with their black and white plumage and yellowish legs. The feet are only partially webbed, and the magpie goose feeds on vegetable matter in the water, as well as on land. Males are larger than females. Unlike true geese, their molt is gradual, so no flightless periods result. Their voice is a loud honking.

Tassonomia

Nome scientifico

Anseranas semipalmata

Autorità

(Latham, 1798)

Ordine

Anseriformi

Famiglia

Anseranatidae

Genere

Anseranas

Areale e habitat

Migrazione

Nomadic movement

Comportamento

The magpie goose is found in a variety of open wetland areas such as floodplains and swamps, where they wade and swim. They eat mostly vegetation such as dry grass blades, grass seeds, spike rush bulbs and wild rice.<p>Magpie geese are fairly sedentary apart from some movement during the dry season. They are colonial breeders and are gregarious outside of the breeding season when they can form large and noisy flocks of up to a few thousand individuals. Magpie geese nest on the ground or in trees where they can be five meters or higher above the ground. Their typical clutch is between 5-14 eggs. Some males mate with two females, all of which raise the young, unlike some other polygamous birds. This may be beneficial when predation of young is high as chicks raised by trios are more likely to survive.<p>This species is plentiful across its range, although this is significantly reduced in comparison to the range at time of European settlement. The range once extended as far south as the Coorong and the wetlands of the southeast of South Australia and Western Victoria. For Australia as a whole, it is not threatened and has a controlled hunting season when numbers are large. However, most of the southern populations were extirpated in the mid-20th century by overhunting and habitat destruction. The species has been subject to reintroduction projects such as Bool Lagoon between Penola and Naracoorte. Populations in more northern areas have again reached a level where it can be regularly utilized by hunters, although not in the example provided. The magpie goose was listed as near threatened on the 2007 advisory list of threatened vertebrate fauna in Victoria. In the December 2007 Flora and Fauna Guarantee Act list of threatened fauna, it is also listed. As of early 2008, an Action Statement for the recovery and future management of this species had not been prepared.<p>With the advent of climate change, and more frequent seawater inundations of the current extensive freshwater floodplains, CSIRO scientists argue that magpie geese populations may be at risk.

Conservazione

Tendenza della popolazione

stable