White-headed Duck
Oxyura leucocephala
Remarkable odd-looking diving duck with a long tail, often held cocked. Males have a striking white face and black crown that contrasts with their large blue bill and chestnut body. Female and juveniles have a darker brown bill, more extensive dark crown and pale cheek stripe, similar to Ruddy Ducks. Silent and rarely flies. Rare and local. Usually found in shallow, open water with dense aquatic plants.
识别特征
Adult males have a grey and reddish body, a blue bill and a largely white head with a black cap and neck. Adult females have a grey-brown body with a white face and a darker bill, cap, and cheek stripe. Length is 43–48 cm (17–19 in) and weight is 580–750 g (1.28–1.65 lb).
分类信息
The white-headed duck was originally described as Anas leucocephala by Giovani Antonio Scopoli in 1769. It is currently in the genus Oxyura. Other generic synonyms used in the past include Erismatura, Cerconectes, Gymnura, Undina, Bythonessa, Plectrura, and Pervicauda. Other junior synonyms for the species include Anas mersa, Anas vindila, Anas ruthenica, and Oxyura unifasciata. Its scientific name comes from the Greek Oxyura (from oxus, "sharp", and oura, "tail") and leucocephala (from leukos, "white" and kephalos, "head". The common name white-headed duck, like the specific name, refers to its white head.<p>It interbreeds with other species in its genus, such as the ruddy duck. The hybrids are fully fertile and capable of having viable offspring with both parent species.<p>The species is monotypic. Different populations of the white-headed duck do not display significant genetic differences. However, some studies have found that they do display morphological differences, with western populations being larger in size, having darker ventral coloration, and males having more yellow feathers on their back. Dark phase birds have only been found in the western populations.<p>In the genus Oxyura, it is generally thought to be related most closely to Maccoa duck. Some studies have also found that these two species form a clade with the blue-billed duck, although this is disputed and species relations between Oxyura ducks are unresolved.
- 学名
- Oxyura leucocephala
- 命名信息
- (Scopoli, 1769)
- 目
- Anseriformes
- 科
- Anatidae
- 属
- Oxyura
分布与栖息地
This duck breeds in Spain and North Africa, with a larger population in western and central Asia. Their breeding habitat is large tracts of open water, such as lakes and ponds including artificial water bodies, with dense stands of aquatic plants to provide shelter and nesting sites. Individuals are fairly frequently reported well north of their breeding range, but as with many wildfowl, the status of these extralimital records is clouded by the possibility of escapes from collections.
- 迁徙
- Complete migrants
行为
These birds dive and swim under water. They are omnivorous, with vegetable matter predominating. They are reluctant to fly, preferring to swim for cover.
保护状况
This duck is considered endangered due to a large reduction in populations in the last 10 years. Most of this decline is due to habitat loss and hunting, but interbreeding of the Spanish population with the introduced ruddy duck (Oxyura jamaicensis) is a more recent threat. This has led to the attempted eradication of the American species from western Europe.<p>The white-headed duck is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies, and the International Union for Conservation of Nature has rated the bird's conservation status as being "endangered".
- 种群趋势
- declining
照片
分布
其他鸟类
Reunion Bulbul
Hypsipetes borbonicus
A medium-sized dark gray bird with a white eye, a black cap, and a carrot-colored bill. Endemic to the island of Reunion. Found in humid forest as well as secondary forest and forest dominated by exotic trees; now mostly confined to middle and high elevations. Often in small, noisy groups. Somewhat similar to male Reunion Cuckooshrike, but easily separated by the orange bill and pale eye. The song is an unmusical but varied series of rattling, metallic, and scraping notes, often given from a high perch. The calls include a “chek” note and a long mew.
Gray-faced Petrel
Pterodroma gouldi
A large, all-dark gadfly petrel found across the Tasman Sea and the temperate and subtropical southwest Pacific Ocean. Note the gray face, chin, and throat and the stout bill. Wings long and narrow. In New Zealand, breeds on offshore islands off the North Island as well as on some mainland cliffs and headlands near the sea. Gives an “o-hi” or “o-hoe” call when flying above breeding areas or a loud “si-si-si” when on land or in burrows. Other dark gadfly petrels are rare off the New Zealand mainland but the similar Providence and dark-morph Kermadec Petrels have white patches on the underwing; the latter also lacks any gray on its face. The rarely-seen Kerguelen Petrel is smaller, with a shorter bill and a pale edge on the underwing.
Bronze Ground Dove
Pampusana beccarii
A rotund, short-legged ground-dwelling dove that usually runs rather than flies when startled. Both sexes have a brown body with bluish-gray chest and head. Males have an iridescent pink shoulder patch. Most obvious identification feature in the field is the glowing white eye-ring of the male, especially in more eastern populations such as those in the Solomon Islands. On mainland New Guinea, the species is a resident of upper-elevation montane forest. No other similar species occur in its altitudinal range. Gives a typical dove-like “woo-oop” call which is quiet and easily missed.
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