Xenicus lyalli (Rothschild, 1894)
Az egyetlen röpképtelen énekesmadár, a szigeti álfakusz (Xenicus lyalli) otthona a parányi Stephens sziget volt. E faj populációját egyetlen földi teremtmény - a világítótorony őrének macskája - pusztította ki.
This highly unusual passerine is perhaps one of the most splendid and remarkable of extinct birds. Discovered in the 1890s on a small islet in the Cook Strait of New Zealand, it succumbed to extinction after a single feline exterminated the entire population. It was in fact virtually extinct when Rothschild published his description of it and could very well have gone extinct without a trace.
Description: Average length: 10 cm (4"). The adult male Stephen Island Wren was brown above and greenish-yellow below with brownish to grayish feather margins, creating a mottled appearance. The superciliary streak, chin, and throat were the same color as the breast and belly, while the flanks were the color of the head, back, and wings. The adult female was the same as the male but with a duller plumage and subtler mottled appearance. The lower mandible, legs, and feet in both sexes were pale brown, while the upper mandible was dark brown with a horn-colored tip. The tail was very short and the bill very stout and robust.
Similar Species: No other species on Stephen Island look anything like this bird.
Voice: This species' voice was never described.
Behavior: All that is known about this species was recorded by the lighthouse keeper on Stephen Island. The bird was apparently most active during twilight hours and was perhaps nocturnal. It ran very fast, like a mouse, but was evidently flightless or at most a weak flyer. This is indicated by the bird's short, rounded wings and soft plumage.
Habitat: The Stephen Island Wren was recorded to have emerged from holes in rocks and to have spent time skulking among these.
Distribution: This species was endemic to Stephen Island in the Cook Strait of New Zealand, an islet with an area of about 2.6 square kilometers (one square mile); the wren had possibly the smallest natural range of any other bird species.
Taxonomic Relationships: Xenicus lyalli, being an isolated form, is probably not closely related to the other three species of its family Acanthisittidae, but is perhaps somewhat close to X. gilviventris. X. lyalli was originally described in the genus Traversia, which is now of disuse. A name given to this species by Buller in 1895, X. insularis, is invalid—Rothschild's name lyalli has priority over insularis.
Status: The Stephen Island Wren is undoubtedly extinct. It was recorded by the lighthouse keeper Lyall on only two occasions in 1894. However, it is Lyall's cat Tibbles, not Lyall himself, who is given credit for the discovery of the species. This cat killed individuals frequently and later deposited them to its owner. Ten specimens exist today and are distributed throughout five museums. It is generally viewed that Tibbles alone exterminated the entire population of wrens; if this is indeed the case, then the population must have been extremely small and particularly vulnerable due to flightlessness. At any rate, the species went extinct within a short period and represents one of the more curious extinctions in birds.
Note: Xenicus lyalli and X. longipes are not the only extinct members of the Acanthisittidae. Three fossil species, known from the Holocene of New Zealand, have been found: Dendroscansor decurvirostris Millener and Worthy, 1991, Pachyplichas yaldwyni Millener, 1988, and P. jagmi Millener, 1988.
Fuller Errol. 1987. Extinct Birds. New York: Facts on File Publications. Greenway, James C., Jr. 1967. Extinct and Vanishing Birds of the World. New York: Dover Publications, Inc.
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