Lesser Black-backed Gull
Larus fuscus
Slender, long-winged gull, slightly smaller than Herring Gull. Adults show dark gray back and yellow legs; in winter note fairly heavy streaking on head and neck. Takes four or five years to reach adult plumage; immatures can be difficult to distinguish from other gulls, especially Herring. On first- or second-year birds, look for contrastingly whitish head with dark smudge around the eye, long wings, dark bill, whitish rump and tail base, and evenly dark wings in flight. Can be found around any body of water but prefers beaches and flats. Often with flocks of other large gulls. Common in Eurasia, wintering to Africa and Southeast Asia. Population in North America has increased dramatically in the last couple decades; now regular (even fairly common!) on the Atlantic coast, rarer inland and farther west.
识别特征
The lesser black-backed gull is smaller than the European herring gull. The taxonomy of the herring gull / lesser black-backed gull complex is very complicated; different authorities recognise between two and eight species. This group has a ring species distribution around the Northern Hemisphere. Differences between adjacent forms in this ring are fairly small, but by the time the circuit is completed, the end members, herring gull and lesser black-backed gull, are clearly different species. The lesser black-backed gull measures 51–64 cm (20–25 in), 124–150 cm (49–59 in) across the wings, and weighs 452–1,100 g (0.996–2.425 lb), with the nominate race averaging slightly smaller than the other two subspecies. Males, at an average weight of 824 g (1.817 lb), are slightly larger than females, at an average of 708 g (1.561 lb). Among standard measurements, the wing chord is 38 to 45 cm (15 to 18 in), the bill is 4.2 to 5.8 cm (1.7 to 2.3 in), and the tarsus is 5.2 to 6.9 cm (2.0 to 2.7 in). A confusable species is the great black-backed gull. The lesser is a much smaller bird, with slimmer build, yellow rather than pinkish legs, and smaller white "mirrors" at the wing tips. The adults have black or dark grey wings (depending on race) and back. The bill is yellow with a red spot at which the young peck, inducing feeding (see fixed action pattern). The head is greyer in winter, unlike great black-backed gulls. Annual moult for adults begins between May and August and is not complete on some birds until November. Partial prebreeding moult occurs between January and April.<p>Young birds have scaly black-brown upperparts and a neat wing pattern. They take four years to reach maturity. Identification from juvenile herring gulls is most readily done by the more solidly dark (unbarred) tertial feathers.<p>Their call is a "laughing" cry like that of the herring gull, but with a markedly deeper pitch.
分类信息
The lesser black-backed gull was one of the many species originally described by Carl Linnaeus in his 1758 10th edition of Systema Naturae, and it still bears its original name Larus fuscus. The scientific name is from Latin. Larus appears to have referred to a gull or other large seabird, and fuscus meant black or brown.<p>The five recognized subspecies are:
- 学名
- Larus fuscus
- 命名信息
- Linnaeus, 1758
- 目
- Charadriiformes
- 科
- Laridae
- 属
- Larus
分布与栖息地
Lesser black-backed gulls have expanded their range westwards, first colonising Greenland in the 1980s. The species has not yet bred in the United States, although hybrid pairs with American herring gulls have been recorded twice.
- 繁殖区
- PAL : Greenland, Iceland, w Europe to nc Siberia
- 非繁殖区
- to sw Europe, wc, ec Africa, nw India, and e North America
- 迁徙
- Complete migrants
保护状况
- 种群趋势
- rising
照片
分布
鸟叫声
其他鸟类
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