Ross's Goose
Anser rossii
Cute miniature version of Snow Goose with smaller body, shorter neck, and stubbier bill. Pay special attention to the bill: short, with a straighter border where it meets the face, a much less obvious dark “grin patch,” and often bluish-gray color at the base. Also note clean white head; Snow Goose typically has yellowish staining on face. Hybrids with Snow Goose are rare but regular; some intermediates might be best left unidentified. Dark morph Ross’s is extremely rare. Typically found in flocks, but individuals may be found with other geese species. Frequently in large mixed flocks with Snow Geese. Occurs in fields, marshes, and lakes during migration and winter; breeds on Arctic tundra.
识别特征
Ross's goose have a rounded head above a short neck. The bill is short and triangular, and has a bluish base with warty structures that increase in prominence with age. Adults are identified by all-white secondary feathers, while juveniles' will be dark centered. Females average 6% smaller than males. Legs will begin as olive gray on goslings and turn deep red as they mature.<p>There is no geographic variation or identified subspecies. Related species include other Anser geese, particularly the lesser snow goose, where the two mtDNA lineages imply frequent hybridization. Two hypotheses about the evolution of Ross's goose are that they arose from a population of snow geese that were isolated by glacial advance or in a refugium that remained ice free.<p>Measurements:[citation needed]
分类信息
Ross's geese, along with other "white geese" (i.e., snow goose, emperor goose) previously belonged to the genus Chen, however, recent genetic sequencing has concluded that this genus was polyphyletic with the Anser genus, where most taxonomists now place Ross's goose and its allies. <p>Members of the Chen genus were officially transferred to Anser in the International Ornithological Committee's World Bird List version 6.3 in 2016.
- 学名
- Anser rossii
- 命名信息
- Cassin, 1861
- 目
- Anseriformes
- 科
- Anatidae
- 属
- Anser
分布与栖息地
Landscape in the central Arctic is dominated by flat plains with some rock outcrops and drumlins, wet meadows, and marshy tundra. Vegetation includes patches of dwarf birch, willow, grasses, sedges, and low-growing vascular plants including crowberry, lapland rosebay, and lousewort. Large colonies of nesting birds can cause extensive damage to plants by overgrazing.
- 繁殖区
- NA : n Canada
- 非繁殖区
- s, w USA and n Mexico
- 迁徙
- Complete migrants
行为
Ross's geese form large nesting colonies on islands in shallow lakes and adjacent mainland, building nests on the ground made of twigs, leaves, grass, moss, and down. Females lay an average of 4 eggs per clutch and incubate the nest for 21–23 days.<p>A study of ground-based sampling along the McConnell River on the west coast of Hudson Bay reported a population of about 81,000 nesting Ross's geese.<p>These birds migrate from their Canadian nesting grounds by mid-October, probably in response to limited food before freezing temperatures set in, and begin their return in mid-April to May.<p>Like most geese, they are grazers that feed on grasses, sedges, and small grains. They often forage in large mixed flocks with snow geese.<p>
保护状况
- 种群趋势
- rising
照片
分布
鸟叫声
其他鸟类
South Island Wren
Xenicus gilviventris
A perky, upright wren restricted to alpine regions in the South Island of New Zealand. Has a very short tail and rounded wings, but distinctive long legs and toes. Male is a mossy green above and pale gray below, with noticeable yellow flanks and a creamy eyebrow. Female has duller plumage. Stance is often erect; constantly bobs up and down, flicking its wings, before hopping and running. Flies very short distances. Seen out in the open in rocky boulder fields, hence its common New Zealand name of “rock wren.” Gives a high-pitched three-note call which travels well in the open alpine terrain. Pairs will sometimes duet.
Atherton Scrubwren
Sericornis keri
Small mostly terrestrial bird of rainforest and wet eucalypt woodlands in a very small range in the Atherton Tabelands of far northern Queensland. Brownish above, grayish yellow below, with long pointed bill, long pinkish legs, and off-white eyering. Forages for insects mostly on the ground or in the lower canopy. Compare Large-billed Scrubwren, which is paler, less likely to feed on the ground, slightly smaller, and has a more twittering call. Song is variable, often including repeated two-note elements.
Mascarene Paradise-Flycatcher
Terpsiphone bourbonnensis
A pretty and distinctive bird that always lacks the long tail streamers possessed by some paradise-flycatchers. Note the rufous back and tail and the gray underparts. Males and females differ slightly: males have a black cap and a blue eye-ring, whereas females have a dark-gray cap without a distinctive eye-ring. Fairly common on Reunion in all types of humid forest. Rare on Mauritius in remnant rainforest patches. Calls include a tearing “sree-sreeet” and an agitated twittering. The song is a long musical series of “twee” notes.
开始您的观鸟之旅
在户外识别鸟类，并在下一次观察时随手查阅鸟类图鉴。