Black-capped Gnatcatcher
Polioptila nigriceps
Long-tailed little bird of dry forest and scrub in northwest Mexico. Found as singles, pairs, or family groups, usually foraging at low to middle levels. Breeding plumage male (March–August) has black cap, but other plumages very similar to Blue-gray Gnatcatcher, a common migrant throughout the range of Black-capped. These species best separated by call note: Black-capped has lower and rougher call than mew of Blue-gray. Also note Blue-gray often has a pinkish base to its smaller bill (gray on Black-capped), a more distinct white eyering (face a little more "open" on Black-capped), and a shorter, less strongly graduated tail.
识别特征
The black-capped gnatcatcher is 10 to 12 cm (3.9 to 4.7 in) long and weighs 5 to 8 g (0.18 to 0.28 oz). Adults are blue-gray on the upperparts with white underparts. They have a long slender bill and a long black tail with mostly white outer feathers. Males in alternate (breeding) plumage have a glossy black cap. The female's gray upperparts have less of a bluish tint but are otherwise similar to the non-breeding male. This species is very similar to the black-tailed gnatcatcher (P. melanura).
分类信息
The black-capped gnatcatcher has at times been treated as conspecific with the white-lored gnatcatcher (Polioptila albiloris). Two subspecies are recognized, the nominate Polioptila nigriceps nigriceps and P. n. restricta.
- 学名
- Polioptila nigriceps
- 命名信息
- Baird, SF, 1864
- 目
- Passeriformes
- 科
- Polioptilidae
- 属
- Polioptila
分布与栖息地
The nominate black-capped gnatcatcher is found in western Mexico from central Sinaloa south to Colima. P. n. restricta is found mostly in western Mexico from eastern Sonora south to northern Sinaloa. It has occasionally nested just across the U.S. border in the Madrean sky islands area of southernmost Arizona. In the northern part of its range it inhabits mesquite thickets near riparian corridors. To the south it inhabits thorn scrub and arid deciduous woodlands. In elevation it occurs mostly below 500 m (1,600 ft). The species is primarily non-migratory, though the northernmost birds might move south after breeding.
- 迁徙
- Resident species
行为
The black-capped gnatcatcher's diet has not been documented. It is assumed to be arthropods like the diets of other gnatcatchers. They forage actively in trees or shrubs, gleaning foliage and sometimes sallying to catch insects.<p>The black-capped gnatcatcher's breeding season spans from March to June, with the last fledging in July. The nest is a small cup constructed of twigs cemented with spider silk, lined with softer material, and placed on small branches of a low tree or shrub. The clutch size is four. Parasitism by brown-headed cowbirds (Molothrus ater) has been observered in Jalisco.<p>The black-capped gnatcatcher's song is complex and rambling [1]. It also has a "mewing" call that is sometimes repeated [2].
保护状况
- 种群趋势
- declining
照片
分布
鸟叫声
其他鸟类
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Neophron percnopterus
Odd-looking, pale, medium-sized vulture with a bare, solemn-looking yellow face. The bill is narrow with a black tip. In flight, the deep-fingered black flight feathers contrasting with white inner feathers may recall White Stork, but the tail is wedge shaped. Juveniles are dirty brown with bare gray faces. An inhabitant of open or semiopen areas, nesting on cliffs and less frequently in trees. Scavenges at rubbish dumps in addition to carcasses, but sadly is in decline over much of its wide range.
Carrion Crow
Corvus corone
The quintessential big black crow, without obvious field marks. Juvenile Rook has longer, more pointed bill with more extensive feathering on base. Smaller than Common Raven, which has longer, wedge-shaped tail, heavier bill, shaggy throat, and deeper voice. Ravens soar and glide readily, whereas crows typically flap continuously. Common in varied open and semi-open habitats from towns and farmland to open woodland and moorland. Found in pairs or small groups; large flocks only at roosts. Typically gives raucous caws.
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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