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Nov 12 2011

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White-headed Duck (Oxyura leucocephala)

White-headed Duck

[order] ANSERIFORMES | [family] Anatidae | [latin] Oxyura leucocephala | [authority] Scopoli, 1769 | [UK] White-headed Duck | [FR] Erismature a tete blanche | [DE] Weisskopf-Ruderente | [ES] Malvasia Cabeciblanca | [NL] Witkopeend

Subspecies

Monotypic species

Genus

The stiff-tailed ducks are part of the Oxyurinae subfamily of ducks. All have, as their name implies, long stiff tail feathers, which are erected when the bird is at rest. All have relatively large swollen bills. These are freshwater diving ducks. Their legs are set far back, making them awkward on land, so they rarely leave the water. Their unusual displays involve drumming noises from inflatable throat-sacs, head throwing, and erecting short crests. Plumage sequences are complicated, and aging difficult. Plumage is vital for survival because of this animals tendency to spend time in the water. Without plumage this duck would die of hypothermia because of an inability to regulate its body temperature. A fossil species from the Late Pliocene or Early Pleistocene of Jalisco (Mexico) was described as Oxyura zapatanima. It resembled a small Ruddy Duck or, even more, Argentine Blue-bill. A larger Middle Pleistocene fossil form from the southwestern USA was described as Oxyura bessomi; it was probably quite close to the Ruddy Duck.

Physical charateristics

Chestnut-brown diving duck with long tail, often cocked vertically. Male has white head, black cap and blue bill, swollen at base. Female has pale face with dark cap and cheek-stripe and blackish, less swollen bill. Similar spp. Ruddy Duck O. jamaicensis is smaller with brighter chestnut plumage. Male has more extensive black cap and dark hindneck and female has narrower facial band and browner cap. Both sexes lack swollen base to bill. Hybrid identification can be very problematic. Voice Low rattling noise uttered during display. Otherwise generally silent.

Listen to the sound of White-headed Duck

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wingspan min.: 64 cm wingspan max.: 68 cm
size min.: 43 cm size max.: 48 cm
incubation min.: 25 days incubation max.: 26 days
fledging min.: 0 days fledging max.: 26 days
broods: 1   eggs min.: 5  
      eggs max.: 12  

Range

Eurasia : Southwest, Central

Habitat

White-headed Ducks breed in shallow fresh or brackish marshes connected with larger wetland complexes. Such wetlands are often seasonal, created by spring floods and drained at summer, but they are especially productive, being very rich in aquatic vegetation and invertebrates. In winter, White-headed Ducks prefer large brackish or saline lakes.

Reproduction

The species forms monogamous pair bonds of seasonal duration. The nest is usually located over water in emergent vegetation.
Females lay 4-9 eggs, more usually 5 or 6, at 1.5 day intervals, and may relay if the first clutch is removed. Relative to body mass, lays the largest egg of any waterfowl, and total clutch mass may approach 100% of a female’s non-breeding body weight. Incubation begins from April to June in southern Europe, and up to a month later further north. Eggs hatch after 22-24 days in the wild. Only one brood is reared per year. Little information on hatching or nesting success. Brood size at hatching 3-7 ducklings, usually 5-6. The fledging period is 8-10 weeks, somewhat longer than most ducks. Females can breed first at one year old although the proportion doing so is unknown. It is one of the few water birds that moult twice a year, during breeding season and winter, being unable to fly during these periods.

Feeding habits

White-headed Ducks feed almost entirely by diving, mainly at night. Benthic Chironomid larvae are the major diet component at most sites, both for adults and ducklings, but polychaetes (especially in coastal lakes used as wintering sites), amphipods and a variety of other invertebrates are eaten, as well as seeds and vegetative parts of Potamogeton, Ruppia, Scirpus and
many other aquatic plants. The availability of chironomid larvae is a key feature in habitat selection. Wintering birds on Caspian Sea contained snails Hydrobia, red seaweed Polysiphonia, and stonewort Chara, and seeds of Ruppia maritima. Females from central Kazakhstan, in July, contained seeds of Potamogeton and Najas, and waterboatmen Corixa
and Micronecta. Young caught at same time had only insects.

Video White-headed Duck

copyright: youtube


Conservation

Despite uncertainty about the possible large-scale inter-year movement of birds between wintering sites, mid-winter counts indicate that the population of this species has undergone a very rapid decline, which qualifies it as Endangered. The Spanish subpopulation has now stabilised, and it is projected that the global rate of decline will be lower in the next ten years.
The species is Palearctic, with a fragmented breeding distribution extending east from Spain and Morocco in western Europe to western China and western Mongolia, and north from Iran to southern Russia. Divisions between biogeographical populations are
poorly understood (Scott & Rose 1996), but four major populations are thought to remain: a migratory central Asian population
breeding mainly in northern Kazakhstan and southern Russia and wintering in western Asia, the Middle East and in eastern
Europe as far west as Greece; a small and declining migratory east Asian population, wintering in Pakistan and perhaps
originating from southern Russia and Mongolia; a population resident in Spain, the Spanish population has increased from 22 birds in 1977 to around 2,500 wintering birds today; and another resident in North Africa (Tunisia and north-east Algeria).

Most of the population is concentrated in only four countries (Mongolia, Kazakhstan, Russian Federation, and Spain). The most important wintering countries differ from year-to-year, presumably depending on weather conditions. In recent years, ten
countries have held over 1,000 birds (Azerbaijan, Bulgaria, Greece, Islamic Republic of Iran, Israel, Kazakhstan, Russian
Federation, Spain, Turkey, and Uzbekistan. Seven countries hold significant numbers of White-headed Ducks
throughout the year (Algeria, Islamic Republic of Iran, Russian Federation, Spain, Tunisia, Turkey, and Uzbekistan). Since a few years the Spanish population is threatened by hybridisation with the Ruddy Duck, Oxyura jamaicensis, an introduced species from America. The other main threats are over hunting and habitat destrution.
White-headed Duck status Endangered

Migration

Resident and dispersive in west Mediterranean. Mainly migratory in east Mediterranean and Asia.
The western population is resident, numbering about 1,000 birds breeding mainly in Spain but also in Algeria and Tunisia. The eastern population is larger and migratory. White-headed Ducks breed mainly in Turkey, where the biggest eastern population is located (200-300 pairs), while fewer breed in Russia, Iran and occasionally in Romania.
Moult movements are poorly understood, but large flocks of moulting individuals gather on certain sites (e.g. the Sudochie wetlands in Uzbekistan, and Lake Tengiz in Kazakhstan). Departure from breeding localities begins in late August and is
completed by mid-October. In Central Kazakhstan, largest numbers occur in September, but birds leave the region completely by mid-October. In Uzbekistan, major passage through the Amu Darya delta in October. In Pakistan, birds first appear in October and leave by the end of March. It is currently unknown whether there is interchange between the Spanish and North African populations. However, the recent increase in the number of White-headed Ducks in Morocco suggests that interchange does occur. Emigration of birds from Algeria or Tunisia was suggested as a possible explanation for the peak count of 4,489
birds in Spain in September 2002. However, as over 1,000 ducklings were hatched at El Hondo that year, it seems equally likely that these numbers could be explained by a bumper breeding year.

Distribution map

White-headed Duck distribution range map

Literature

Title Conservation of the globally threatened white-headed duck,
Oxyura leucocephala, in the face of hybridization with the North
American ruddy duck, Oxyura jamaicensis: results of a control trial
Author(s): Baz Hughes, Iain Henderson, Peter Robertson
Abstract: The North American ruddy duck, introduced into Eur..[more]..
Source: Acta Zoologica Sinica 52(Supplement): 576-578, 2006

download full text (pdf)

Title International Single Species Action Plan
for the Conservation of the
White-headed Duck
Author(s): Baz Hughes, James Robinson, Andy Green, David Li & Taej Mundkur
Abstract: The White-headed Duck Oxyura leucocephala is liste..[more]..
Source: AEWA Technical Series No. 8,2006

download full text (pdf)

Title Multi-annual spatial and numeric dynamics of the white-headed duck Oxyura leucocephala in southern Europe: seasonality, density dependence and climatic variability
Author(s): PABLO ALMARAZ and JUAN A. AMAT
Abstract: A statistical model is developed for the globally ..[more]..
Source: Journal of Animal Ecology (2004) 73, 1013 -1023

download full text (pdf)

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