Vaux's Swift
Chaetura vauxi
Very small swift with stiff, quick wingbeats. Grayish overall with paler throat and brownish rump. Relatively short-winged and short-tailed compared with other similar swifts. Often in small flocks. Listen for its high-pitched chips and trills. Feeds on aerial insects over a variety of habitats, including forests, fields, towns, and bodies of water. Multiple populations are surely distinct species. Migratory population breeds extensively in the western U.S. and Canada, wintering to Central America. Resident “Richmond’s Swift” occurs through much of Mexico and Central America, and is darker overall than migratory Vaux’s with a more contrasting pale throat and browner rump. There are also resident populations on the Yucatan peninsula and in western Venezuela, for which identification criteria are not well-defined. Range overlaps with several other similar swifts in Mexico and Central America. Vaux’s is smaller with quicker wingbeats than Chimney Swift or Gray-rumped Swift, with higher-pitched calls.
识别特征
This is a small swift, even compared to other Chaetura species, at 10.7 to 11.2 cm (4.2 to 4.4 in) long and weighing 18 g (0.63 oz). The northern populations are slightly larger at 11.5 cm (4.5 in), probably according to the Bergmann's Rule and/or migration requirements. It has a cigar-shaped body, crescentic wings and a short bluntly squared-off tail. The head, upperparts and wings are dusky black, and the underparts, rump and tail coverts are greyish brown. The throat is paler grey, becoming whitish in northern birds. The sexes are similar, but juveniles have dusky bases to the throat feathers.
分类信息
- 学名
- Chaetura vauxi
- 命名信息
- (Townsend, JK, 1839)
- 目
- Apodiformes
- 科
- Apodidae
- 属
- Chaetura
分布与栖息地
Vaux's swift breeds in highlands from southern Alaska to central California and from southern Mexico, the northern Yucatán Peninsula, to eastern Panama and northern Venezuela. The United States' populations are migratory, wintering from central Mexico south through the Central American breeding range. The resident breeding birds in the southern part of the range are sometimes considered a separate species, dusky-backed swift, Chaetura richmondi.Preferred habitats include old growth coniferous or deciduous forests consisting of coniferous and deciduous vegetation; requires large, hollow trees for nesting.
- 迁徙
- Complete migrants
行为
This is a gregarious species, with flocks of 30 or more birds, and often with other swift species, such as white-collared, especially at weather fronts. It flies with a mixture of stiff wing-beats and unsteady glides. It has more varied calls than others in the genus, with a mixture of chattering, buzzes, squeaks and chips.<p>The swift feeds in flight on flying insects, including beetles, wasps, termites and flying ants. It forages over forests and more open areas, including towns.<p>Vaux's swift breeds in the mountains and foothills, from southeastern Alaska and Montana to central California, mainly above 700 m (2,300 ft). It builds a cup nest of twigs and saliva on a vertical surface in a dark cavity, such as a tree hole, cliff crevice or attic. It lays three white eggs between March and July. It spends winters in the tropics.<p>Vaux's swift builds saucer-shaped nests of twigs or spruce and pine needles stuck to an inside surface of a hollow tree or chimney, between 20 inches and 6 feet from the bottom of the cavity.
保护状况
- 种群趋势
- declining
照片
鸟叫声
其他鸟类
Gray-crowned Babbler
Pomatostomus temporalis
Large, conspicuous songbird with long decurved bill, dark gray mask, pale gray crown, and whitish eye. Underparts variably reddish brown, with white throat and upper breast. Juvenile similar but eye dark. Forages in small groups actively, almost comically, through open woodlands, including agricultural areas with some remaining native vegetation.
Wilson's Bird-of-Paradise
Diphyllodes respublica
A fairly small bird of foothill forest on Waigeo and Batanta islands. Dark blue feet and strange pale blue skin on the top of the head divided by thin, black lines. Male has bottle green chest, red back and yellow on the back of the neck, all or which it can erect into elaborate ornamentation during the display at a court on the ground. Remarkable flattened, curly tail feathers reflect blue. The female is brown above with rufous in the wing and barred below. Unmistakable in range. Male gives a series of loud, downslurred “piuu!” calls, increasing in volume.
Tongan Megapode
Megapodius pritchardii
A plump, mostly ground-dwelling bird with long yellowish legs and a dark gray body with slightly browner wash on the wings and back. Head mostly dark gray, with bright orange beak and whitish crest. Good views may show blood-red bare skin around the eye and throat. Found in mature woodland with open understory. Nests on crater lake islands. Resident, with no record of vagrancy. Very vocal, most frequently heard in groups giving chorus of loud piping whistles and shrill cries. Calls are usually a staccato one-note whistle. Unmistakable, as it is the only scrubfowl in its range.
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