Crested shelduck
Kingdom
Phylum
Class
Order
Family
Genus
SPECIES
Tadorna cristata

The crested shelduck (Tadorna cristata ), or Korean crested shelduck, is a species of bird in the family Anatidae. It is critically endangered and may be extinct. The male crested shelduck has a greenish-black crown, breast, primaries, and tail, while the rest of its face, chin, and throat are brownish black. The male's belly, undertail coverts, and flanks are a dark grey with black striations. The upper wing coverts are white, while its speculum is an iridescent green. The female has a white eye ring, black crest, white face, chin, throat, neck, and uppers wing coverts and a dark brown body with white striations. Additionally, both sexes have a distinctive green tuft of feathers protruding from the head.

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Very little is known about this species because of the limited number of observations of it. It apparently breeds in Korea and eastern Russia and is probably a relict species that had a wider distribution in prehistoric times. Some think that this species is extinct, although occasional sightings are reported, including a number of reports made between 1985 to 1991 from the interior wetlands of China. Due to the persistent reports of the species' survival, it is listed as critically endangered. However, the crested shelduck has not been definitively sighted since 1964.

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Appearance

The crested shelduck is sexually dimorphic, with the male possessing a greenish-black crown, breast, primaries, and tail, while the rest of its face, chin, and throat are brownish black. The male's belly, undertail coverts, and flanks are a dark grey with black striations. The upper wing coverlets are white, while its speculum is an iridescent green. The female has a large white eye ring, black crest, and white face, chin, throat, neck, and upper wing coverts. It also has a dark brown body with white striations. Both sexes have a green tuft of feathers protruding from their head. The crested shelduck is about 63 to 71 centimetres (25 to 28 in) long, and therefore is slightly larger than a mallard. Its bill and legs are pinkish, though those of the female are paler than those of the male. The bill of the male has a small, knob-like appendage at its base. The plumage of the immature is unknown.

Distribution

Geography

Continents
Biogeographical realms

The crested shelduck has been collected near Vladivostok in Russia and near Busan and Kunsan in Korea. It has been proposed that the species breeds in far-eastern Russia, northern North Korea, and northeast China and winters in southern Japan, southwest Korea, and along the east China coast as far south as Shanghai. It is believed to have a relict range, or to have been more widespread in historic times.

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This species is believed to live in a wide variety of wetland and deep-water habitats at varying elevations. While all collected individuals are from the coast, especially near river mouths, recently there have been a number of reports from interior wetlands in northeastern China. It has been speculated that this species may breed in mountainous areas either away from water or on volcanic lakes.

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Crested shelduck habitat map
Crested shelduck habitat map
Crested shelduck

Habits and Lifestyle

Though not much is known about this shelduck, it is believed to be migratory, traveling from Siberia in the breeding season to Korea, southern Russia, and Japan for the winter. The crested shelduck is believed to eat aquatic vegetation, agricultural crops, algae, invertebrates, mollusks, crustaceans, carrion, and garbage. It has been suggested that this shelduck may be a nocturnal feeder. While its nest has not been described, similar shelducks nest in burrows and cavities; it has also been suggested that this species may nest in tree cavities. It has been proposed that this species lays less than ten eggs which the female alone incubates. It is believed to breed from May to July. The shelduck has been observed in flocks of two to eight birds.

Lifestyle
Seasonal behavior

Diet and Nutrition

Population

Conservation

The crested shelduck has never been numerous in modern times, though it is thought to have been more widespread historically due to its presence in Japanese aviculture. The species is known from only a handful of sightings and some retroactively declared it extinct in 1916 after a female was shot at Busan, South Korea. In 1943, a sighting of this bird was reported near Chungcheongbukdo, building hopes that the species persisted. A group of three birds, two females and a male, was sighted by two Russian students in 1964 in the Rimsky-Korsakov Archipelago near Vladivostok with a small flock of harlequin ducks. In 1971 it was reported from North Korea's northeast coast and in 1985 two were reported from eastern Russia. However, there are severe doubts about the accuracy of the 1971 record. A recent survey of Chinese hunters resulted in a number of unconfirmed reports from northeastern China. For example, a Chinese forest worker claimed that he unknowingly ate two in 1984. There are also unconfirmed reports of about twenty crested shelducks in the Dashanbao region of Yunnan, though many believe this flock to be a misidentified flock of ruddy shelducks. It is believed that, if the species survives, there likely are fewer than 50 individuals.

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This species is threatened with extinction due to habitat loss, hunting, and overcollecting. In an attempt to gather reports of this species and raise awareness to prevent hunters from consuming this species, 300,000 leaflets were distributed in Russia, Japan, China, South Korea, and North Korea in 1983, with the only resulting report being the 1971 North Korea record. 15,000 leaflets were distributed in northeastern China in 1985 and 1991. While this garnered 82 reports of the species, follow-up surveys of the area failed to find the shelduck. The Tumangan Development Project is threatening to destroy potential habitat in the area of several of the historic records.

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References

1. Crested shelduck Wikipedia article - https://en.wikipedia.org/wiki/Crested_shelduck
2. Crested shelduck on The IUCN Red List site - https://www.iucnredlist.org/species/22680021/132052989

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