Laysan duck
| Laysan duck | |
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| Bird at Midway | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Anseriformes |
| Family: | Anatidae |
| Subfamily: | Anatinae |
| Genus: | Anas |
| Species: | A. laysanensis |
| Binomial name | |
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Anas laysanensis Rothschild, 1892 |
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| Distribution map of the Laysan duck | |
The Laysan duck (Anas laysanensis), also known as the Laysan teal, is a dabbling duck endemic to the Hawaiian Islands. Fossil evidence reveals that Laysan ducks once lived across the entire archipelago, but today survive only on Laysan Island. The duck has evolved several behavioral traits linked to the absence of ground-based predators in its habitat; these include freezing or running to escape danger rather than flying, which made the duck vulnerable to hunting by humans, and the pigs, rats and mongooses they brought with them to Hawaii. By 1860, the ducks had disappeared from everywhere except Laysan Island. The introduction of rabbits brought the bird to the brink of extinction in 1912 with twelve surviving individuals. Rabbits were eradicated from the island in 1923 and numbers of Laysan ducks began to rise, reaching 500 by the 1950s. In an effort to ensure the long-term future of this duck, 42 birds were translocated to Midway Atoll National Wildlife Refuge in 2002. These thrived in their new surroundings, and another group were later relocated to Kure Atoll.
Named by Lionel Walter Rothschild in 1892, the Laysan duck is named after Laysan island, one of the Northwestern Hawaiian Islands. It is a member of the mallard clade of dabbling ducks, and is a highly unusual species, both behaviorally and genetically. Recent evidence suggests they originated from an east Asian, southern hemisphere ancestor of mallards, not from stray migratory mallards (Anas platyrhynchos) as had been reported in the past.
The Laysan duck is teal-sized and dark brown, with a prominent white eye-ring. The bill is short and spatulate, dark green with variable black blotching in males, and dull orange with variable black blotching in females. The Laysan duck usually has a ring of fat around its neck. Some males show faint iridescence on the head or neck and have slightly upturned central tail feathers. The wing has an iridescent purplish-green patch (speculum feathers) in both sexes. Leucistism, or extensive white feathering, is common on the head and neck of older birds. The legs and feet are orange, usually brighter in the male. The annual pre-basic molt is complete, and the ducks lose all their flight feathers and become incapable of flight until new feathers grow in. Wild ducks have been known to live to the age of twelve years, and captive birds have lived to the age of eighteen.
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