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:
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
Migration pattern: Complete migrants.
保护状况
Population trend: rising.
- 种群趋势
- rising
照片
分布
鸟叫声
其他鸟类
Odedi
Horornis haddeni
A small, round-bodied, cock-tailed skulking warbler. Appears three-toned: dark slaty gray below, chestnut brown above, with a paler rufous head and a slightly darker eye-stripe. Prefers dense undergrowth and tangles in forest or on forest edge above 600 meters of elevation, but locally lower. Song is a high-pitched whistle “o-de-di.” Also gives harsh scolding notes.
Freckle-breasted Thornbird
Phacellodomus striaticollis
Medium-sized ovenbird with a long spiky tail. Cinnamon-brown above, paler below, with a darker cap and wings. Note the freckled breast and yellow eyes. Usually found near water, in marshes, gallery forests, and scrub, where it forages on the ground or in the understory. Builds large thorny nests that do not hang from trees, unlike other thornbirds.
Red-billed Tropicbird
Phaethon aethereus
Spectacular seabird, very rarely seen from land but found locally around rocky islands near shore. Usually seen as single birds sitting on the sea or as pairs chasing and screeching around cliffs, often high overhead. Feeds by vertical plunge dives, which produce a plume of water like a mini whale blow. Adult has stout red bill and long white tail streamers. Immature has yellow bill and short, black-tipped tail.
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