Hardhead

识别特征

Hardheads are smaller than most ducks, usually not reaching much more than 45 cm long but sometimes reaching 60 cm, and noticeably more rounded in overall form than most ducks. Both male and female are a fairly uniform chocolate-brown above, with rufous flanks and white undersides (which are often not visible if the duck is in the water). The trailing edges and almost the entire underside of the wings are white. In the male, the eyes are a striking white, in the female, brown.

分类信息

学名

Aythya australis

命名信息

(Eyton, 1838)

目

Anseriformes

科

Anatidae

属

Aythya

分布与栖息地

Hardheads are common in the south-east of Australia, particularly in the Murray-Darling Basin, but also in the wetter country near the coasts. They are moderately nomadic in normal years, but disperse widely in times of drought. Significant numbers reach as far afield as New Guinea, New Zealand, and the islands of the Pacific, where they can remain for some time, even breeding for a season or two.<p>Hardheads prefer larger lakes, swamps and rivers with deep, still water, but are often seen in smaller streams, flooded grasslands, and shallow pools. As a general rule, they avoid coastal waters. They rarely come to land and never perch in trees.<p>Widespread throughout its large range, the hardhead is evaluated as Least Concern on the IUCN Red List of Threatened Species.

繁殖区

AU : Australia and Tasmania, New Zealand, Grande Terre (New Caledonia) and Banks Is. to Tanna (n to s Vanuatu)

非繁殖区

to Sulawesi and e Java

迁徙

Resident species

行为

Like the other members of the pochard group, hardheads feed by diving deeply, often staying submerged for as long as a minute at a time. They slip under the water with barely a ripple, simply lowering their heads and thrusting with their powerful webbed feet. They eat a broad range of small aquatic creatures, and supplement this with water weeds.<p>Hardheads are usually silent, but males have a soft, wheezy whistle and 'whirr'. Females have a loud rattling 'gaark' call.

保护状况

种群趋势

stable