White-headed ducks are usually silent except during sexual display, when they make a low rattling noise.
Communication Channels: acoustic
Perception Channels: visual ; tactile ; acoustic ; chemical
White-headed ducks have been threatened by the introduction of ruddy ducks (Oxyura jamaicensis) to the United Kingdom and their subsequent migration across the western Palearctic. Ruddy ducks and white-headed ducks can hybridize to produce fertile offspring. White-headed ducks are suffering from hybridization in the western end of their range. In addition, male ruddy ducks and male hybrids dominate male white-headed ducks during courtship. White-headed ducks have been listed as endangered on the IUCN Redlist since 2000. They are legally protected in many countries and a conservation program in Spain has led to a large population increase in recent years. Ruddy ducks are also being conserved in Spain, Portugal, and France. A program was launched in 2005 to eliminate the population of ruddy ducks in the United Kingdom with the goal of limiting the amount of hybridization between ruddy ducks and white-headed ducks. An extensive European action plan for the conservation of white-headed ducks was published in 2006 (Hughes et al., 2006). Conservation priorities in Europe include the development of policies to control ruddy ducks, promote protection for key wintering sites of white-headed ducks, and monitor the number of white-headed ducks kept in captivity.
US Migratory Bird Act: no special status
US Federal List: no special status
CITES: appendix ii
State of Michigan List: no special status
IUCN Red List of Threatened Species: endangered
There are no known adverse effects of white-headed ducks on humans.
Before it was banned due to their vulnerable status, hunting of white-headed ducks for meat was commonplace. In addition, the eggs of white-headed ducks are used for human consumption. Subsistence hunting has been cited as an important problem for the conservation of white-headed ducks.
Positive Impacts: food
White-headed ducks eat soft-bodied invertebrates, crustaceans, and aquatic plants. In the lagoons of Cordoba, Spain, the breeding success of white-headed ducks has been negatively affected by the introduction of carp (Cyprinus carpio carpio) into lagoons, because carp directly compete with white-headed ducks for food.
White-headed ducks are omnivorous. When studied, food items from at least 27 families of invertebrates and at least 10 families of aquatic plants were identified in the guts of white-headed ducks. The most important food items are chironomid larvae, the abundance of which affects habitat choice. Angiosperm seeds are an important part of their diet, whereas crustaceans and green plant material are of secondary importance.
Animal Foods: insects; aquatic or marine worms; aquatic crustaceans
Plant Foods: leaves; roots and tubers; seeds, grains, and nuts
Primary Diet: omnivore
White-headed ducks (Oxyura leucocephala) are the only stifftail Oxyurinii native to the Palearctic. White-headed ducks can also be found in parts of the Oriental region and the Ethiopian region. The largest populations of white-headed ducks are found in Russia, Kazakhstan, Turkey, Iran, Afghanistan, Tajikistan, Turkmenistan, Uzbekistan, Armenia, and Mongolia. Central and east-Asian populations tend to be migratory while populations in Spain and North Africa are non-migratory. There are four main populations of white-headed ducks worldwide: two are decreasing, one is stable, and one is increasing. Of the two populations of wintering birds that are decreasing, one is located in central Asia and has a population of 5,000 to 10,000, and one is located in Pakistan and on the verge of extinction. There is a stable population in North Africa of about 500 birds in the winter and an increasing population in Spain that has increased from 22 birds in 1977 to about 2,500 birds as of 2006.
Biogeographic Regions: palearctic (Native ); oriental (Native ); ethiopian (Native )
White-headed ducks inhabit freshwater lakes as well as alkaline, saline, and eutrophic lakes connected with larger wetland complexes (Birdlife International, 2009). The alkaline lakes inhabited have a pH range of 7.8 to 10, which prevents the lakes from freezing. Breeding sites of white-headed ducks contain dense vegetation and are small and shallow, with depths between 0.5 and 3 m. Wintering sites are usually larger, deeper, and contain less emergent vegetation. There are conflicting views about winter habitat selection of white-headed ducks. Some research suggests that freshwater habitats are chosen more in the winter than in the breeding season. Other research suggests that white-headed ducks prefer deep, alkaline or saline waters in winter. However, there is a general consensus that the availability of insect larvae (Chironomidae) is a key component of habitat selection. Benthic chironomids are reasonably tolerant of eutrophication, so white-headed ducks are more tolerant of eutrophication than many other water birds (Green et al. 1996).
Range depth: 0.5 to 3 m.
Habitat Regions: temperate ; saltwater or marine ; freshwater
Aquatic Biomes: lakes and ponds
Due to a lack of banding information, there are no known data on adult or juvenile survival rates.
White-headed ducks exhibit some sexual dimorphism. Males have white heads with black caps and blue bills, which are enlarged at the base. Females have white faces with dark caps, cheek-stripes and less swollen bills. Both males and females range between 43 and 48 cm in length and both have chestnut-brown bodies.
Range length: 43 to 48 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: sexes alike; sexes colored or patterned differently
During the breeding season, white-headed ducks construct their nests in emergent vegetation, which helps hide nests from predators. A “roof” may also be formed over the nest by bending down overhead leaves, providing further disguise from predators. In addition, white-headed ducks dive repeatedly, only re-emerging for short periods of time, which aids in their ability to avoid predators. White-headed ducks are preyed on by gulls (Larus species) and brown rats (Rattus norvegicus). In the Tarelo Lagoon in Doñana, Spain, a large number of abandoned white-headed duck nests were observed after predation by brown rats. White-headed duck nests may also be trampled by cattle. Although it is currently illegal to hunt them, white-headed ducks are easy birds to shoot due to their lack of an escape response when facing hunters. In addition to hunting the ducks, their eggs have been collected for human consumption.
Known Predators:
White-headed ducks are seasonally monogamous. To attract females, male ducks make a low rattling noise.
Mating System: monogamous
White-headed ducks breed from April to June in southern Europe and up to a month later in northern Europe. The timing of the breeding period is thought to be because stable water-levels are necessary during incubation of eggs. Because of this requirement, white-headed ducks breed on small, enclosed, freshwater or eutrophic lakes and tend to choose lakes with shallow water, ranging between 0.5 and 3 m in depth. Nests are located over water in emergent vegetation and consist of cupped stands of stems and leaves. Females become sexually mature at one year of age and lay between 4 and 9 eggs at 1.5 day intervals during the breeding period. The incubation period for eggs is between 22 and 24 days. Relative to their body mass, female white-headed ducks lay the largest egg of any waterfowl. After breeding, white-headed ducks undergo a flightless molting period that lasts 2 to 3 weeks before migration to their wintering grounds. They undergo another flightless molt in late winter as well.
Breeding interval: White-headed ducks breed once yearly.
Breeding season: White-headed ducks breed from April to July.
Range eggs per season: 4 to 9.
Average eggs per season: 5-6.
Range time to hatching: 22 to 24 days.
Range fledging age: 8 to 10 weeks.
Range age at sexual or reproductive maturity (female): 1 (low) years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; oviparous
Although little is known about parental investment in white-headed ducks, it can be inferred that females invest heavily in their young due to the length of the incubation period.
Parental Investment: precocial ; female parental care ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Protecting: Female)
