Grasshopper Sparrow
Ammodramus savannarum
Small, short-tailed, flat-headed sparrow found in weedy grasslands. Warm buffy coloration with clean unstreaked breast. Thin white eyering and yellow patch above eye. Back and wings are patterned with gray and rufous. Easy to see when singing atop a shrub, but can be very secretive much of the year. Best detected by its dry, insect like trill preceded by a few introductory notes. Typically not in flocks.
识别特征
These small sparrows measure 10–14 cm (3.9–5.5 in) in length, span about 17.5 cm (6.9 in) across the wings and weigh from 13.8 to 28.4 g (0.49 to 1.00 oz), with an average of 17 g (0.60 oz). Adults have upper parts streaked with brown, grey, black and white; they have a light brown breast, a white belly and a short brown tail. Their face is light brown with a white eye ring and a dark brown crown with a central narrow light stripe. Adults sport bright yellow feathers at the crook of their underwing, and have a yellow-to-amber patch above their lores. Males and females cannot be distinguished by their plumage, and young birds molt into adult plumage within a few months of fledging.
分类信息
The grasshopper sparrow was described in 1713 by English parson and naturalist John Ray based on a specimen collected in Jamaica. It was described again and illustrated in 1725 by the naturalist and collector Hans Sloane. Both authors used the English name "Savanna bird". When the German naturalist Johann Friedrich Gmelin revised and expanded Carl Linnaeus's Systema Naturae in 1789 he included the grasshopper sparrow. He placed it with the finches in the genus Fringilla, coined the binomial name Fringilla savannarum and cited the earlier authors. The grasshopper sparrow is now placed with two other American sparrows in the genus Ammodramus that was introduced by William Swainson in 1827.<p>Twelve subspecies are recognised:
- 学名
- Ammodramus savannarum
- 命名信息
- (Gmelin, JF, 1789)
- 目
- Passeriformes
- 科
- Passerellidae
- 属
- Ammodramus
分布与栖息地
Their breeding habitat is open fields and prairie grasslands across southern Canada, the United States, Mexico and Central America, the Caribbean. There is a small endangered population in the Andes of Colombia and (perhaps only formerly) Ecuador. In the central USA, birds are quick to locate newly available habitat, and can be attracted to sites by playing conspecific song. The spatial distribution of territories on the landscape can be clumped with several individuals defending territories near to one another interspersed by large areas of unused and apparently suitable habitat. The reasons for this clumping are elusive; aggregation is not related to group defense against predators or brood parasite, cooperative care, extra-pair matings, or kin selection. Appropriate habitat is strongly influenced by plant structure and precipitation amounts during previous seasons. Grasshopper sparrows avoid woody vegetation, and in the wetter parts of their range, prefer fields that are burned every 2–3 years (which reduces encroachment of trees and shrubs) and seek out areas that are moderately grazed by cattle or bison.
- 迁徙
- Complete migrants
行为
Migration pattern: Complete migrants.
保护状况
Population trend: declining.
- 种群趋势
- declining
照片
分布
鸟叫声
其他鸟类
Golden Palm Weaver
Ploceus bojeri
Breeding male is bright yellow with a mostly orange head. The female is duller, though still very yellow. Both sexes show a dark eye in all plumages. Found in coastal savanna and scrub, often in areas with abundant palms, and inland along rivers through dry country. Similar to African Golden-Weaver, and ranges overlap, but separated by the blackish rather than red eyes. Vocalizations are typical of weavers: “chet” notes and a sizzling “radio static” song.
White-rumped Swallow
Tachycineta leucorrhoa
A small swallow usually seen flying low over open and semiopen areas near water. Glossy blue-green above and white below. Note the white forehead and rump. Similar to White-winged Swallow, but lacks white in wings (although juvenile White-winged can show limited white). Told from Chilean Swallow by the presence of a white forehead.
Lake Lufira Masked-Weaver
Ploceus ruweti
A red-eyed masked-weaver with a plain olive-yellow back and pink-brown legs. The breeding male has a black face mask extending to the hind-crown and almost enveloping the head, and a strong chestnut breast and flanks (mid-belly is yellowish). Female and juvenile are dull green above with wingbars, and yellowish below. Pairs and colonies are very localized residents of riverside vegetation, preferring trees to reedbeds for breeding, at Lake Tshangalele and Kiubo Falls in the southeastern DRC. The ranges of most similar masked-weavers do not overlap, but breeding male Tanganyika Masked-Weaver has a less extensive black mask; Katanga and Southern Masked-Weavers are much yellower.
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