|Australian Bush Birds|
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|Magpie Goose - Anseranas semipalmata|
|Adult Magpie Goose at rest with distinctive head and pink feet. The size of the head bump indicates the age of the bird; the bigger the bump, then the older the bird. (Darwin, NT)|
|Part of the flock of Magpie-geese feeding at Fogg Dam Reserve. (nr Darwin, NT)|
The Magpie Goose - Anseranas semipalmata - is a large black and white pied goose; males are 75 to 99 centimetres in length, females 70 to 80 centimetres. Wingspan reaches 1.5 to 1.6 metres. Gathers in large flocks numbering thousands of birds across northern Australia to feed. In dry season geese wander over mudflats of river flood plains to dig up roots of rushes; when water is available they forage around billabong margins and in the shallows, upending in shallow water to reach aquatic plants on the bottom. When feeding prefers open places well away from cover which may conceal an attacker.
|Magpie Goose - page 2|
Head, neck, tail and thighs are black; back and underside are white, stained red-brown in the dry season. Eye brown, bill and bare facial skin grey to pink. Legs, feet and toes yellow-orange, claws grey. Feet are partly webbed. Characterised by a conspicuous knob on the head, usually larger in males than in females but the size varies between individuals and is more an indication of age than anything else.
Juveniles are similar to adults but have black backs and lack knobs on the head.
Both sexes honk loudly, males at a higher pitch than females. A call by a male is answered immediately by females.
When alarmed magpie geese fly away rather than staying on the water.
A male often mates with two females forming a breeding trio but breeding pairs are also found. The breeding cycle begins about October/November as water level in the swamps increases during the wet season; geese separate into breeding pairs and trios and build floating platforms of spike-rush; the male does most of this work. The platforms are used for resting and courtship; each platform is used only for a single season. Shortly before egg-laying (about March/April) the male makes the platform more elaborate adding broken or uprooted shoots of spike-rush until there is a substantial pile about 1.5 metres across and 0.5 metres above water level. After eggs are laid additional material is added around the eggs to form a thick, deep cup.
Eggs are cream, oval, 64-80 by 46-63 millimetres. Both females of a breeding trio use the same nest laying six to nine eggs each. Females and male incubate the eggs for 24 to 25 days. Newly hatched chicks remain in the nest for a day before being led by their parents to feed on shoots and seeds of swamp grass and wild rice.
|Left. Adult Magpie Goose with fully developed head bump.|
Right. Magpie Goose in flight.
|Left. Juvenile Magpie Goose with no head bump.|
Right. Young adult Magpie Goose with white on the back, pink facial skin and small head bump. (Cumberland Chimney, near Georgetown, Queensland).
|Magpie Goose - page 3|
Adults help the young feed by bending seedheads down with their feet so the young can reach them. In deeper water the adults use their long necks to bring up food items for the chicks.
At 11 weeks the young can fly and join their parents in loose flocks which roost for the night then fly out onto the swampy plains to feed during the day. Young birds stay with their parents until the following wet season. If the swamp dries out before the young are fledged they die. For surviving young geese lifespan exceeds 20 years.
As the dry season intensifies, from May onwards, geese feed on bulbs of spike-rush which they dig up from bare, dried mud with their hooked bills. They are nomadic at this time, moving from one drying swamp to the next until they are concentrated around the most permanent water.
Distributed along the north coast from Broome northward through Northern Territory and Queensland to the Clarence River on the mid-north coast of New South Wales. Breeds between the Fitzroy River, WA, and Bowen, Qld. In the dry season wanders more widely. Locally abundant.
|Two Magpie Geese on Lake Cumberland near Georgetown, Qld; black backs indicate these are juveniles.|