Least Tern
Sternula antillarum
Tiny tern with quick flicking wingbeats. A real beach bum, rarely straying far from sand, both on the coast and along inland rivers and lakes. Breeding adults have yellow bill, stumpy yellow feet, white forehead, and black cap. Nonbreeding and immatures have a black bill, blackish nape, and dark shoulder bar, but still always identifiable by size and quick wingbeats. Often seen with other terns. Listen for shrill high-pitched calls.
分类信息
- 学名
- Sternula antillarum
- 命名信息
- Lesson, RP, 1847
- 目
- Charadriiformes
- 科
- Laridae
- 属
- Sternula
分布与栖息地
- 繁殖区
- NA, MA : Great Plains to Texas and n Louisiana; c California and Gulf of California coasts to Oaxaca (w Mexico), El Salvador and Nicaragua; w North Atlantic coast from Maine to Florida, Gulf of Mexico and Caribbean Sea from Bahamas to Lesser Antilles, islands off Yucatan Pen., Belize and n Honduras, and islands n of Venezuela
- 非繁殖区
- n SA coast
- 迁徙
- Complete migrants
保护状况
The population is about 21,500 pairs; it is not currently considered federally threatened, though it is considered threatened in many of the states in which it breeds. Threats include egg and fledgling predators, high tides and recreational use of nesting beaches.<p>The interior subspecies, with a current population of about 7000 pairs, was listed as an endangered subspecies in 1985 (estimated 1000 breeding pairs), due to loss of habitat caused by dams, reservoirs, channelization, and other changes to river systems. It was delisted on 13 January 2021.<p>The western population, the California least tern, was listed as an endangered species in 1972 with a population of about 600 pairs. With aggressive management, mainly by the exclusion of humans via fencing, the Californian population has rebounded in recent years to about 4500 pairs, a marked increase from 582 pairs in 1974 when census work began, though it is still listed as an endangered subspecies. The California subspecies breeds on beaches and bays of the Pacific Ocean within a very limited range of southern California, in San Francisco Bay and in northwestern Mexico. While numbers have gradually increased with its protected status, it is still vulnerable to predators, natural disasters or further disturbance by humans. Recent threats include the gull-billed tern (Sterna nilotica), which can decrease reproductive success in a colony to less than 10%.
- 种群趋势
- declining
照片
分布
鸟叫声
其他鸟类
Brown Jacamar
Brachygalba lugubris
A small-headed bird with a long slender bill. Mostly brown with a glossy bluish black, wings, and tail that contrasts with a white chin and belly. Northern subspecies have buffy underparts. Normally sits upright on an exposed branch; often in groups where they sally out to catch insects. Found at the border and in the canopy of forests and savanna woodlands.
Pink-necked Green-Pigeon
Treron vernans
Brightly-colored tree-dwelling pigeon. Adult male has a powder-pink neck, orange breast patch, gray-blue head, and yellow belly. Adult female is much plainer, tea-green above and brighter yellow-green below. Both sexes have striking black-and-yellow wing feathers and yellow spotting on the undertail coverts. Adaptable, and can be found in mangroves, open coastal forests, parks, gardens, and plantation edges. Primarily a lowland species, but can on occasion be found in foothills. Social, often gathering in flocks; occasionally mixes with other green-pigeons. Unlike many other pigeons, not very vocal; occasionally gives strange, alien-sounding coos.
Mongolian Accentor
Prunella koslowi
A very plain accentor of dry, open areas with sparse, scrubby vegetation. Patterning more closely resembles that of a lark or a pipit than another accentor: pale sandy brown all over with a paler belly and a finely streaked back. For an accentor, oddly shy and skulking, usually sticking to cover and infrequently vocalizing.
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