Socorro Mockingbird
Mimus graysoni
Only on Socorro Island, where in danger of extinction due to feral cats and overgrazing. Largely restricted to forest and edge on higher slopes of the island. Note the rather plain gray-brown head and upperparts, narrow whitish wingbars, whitish underparts with faint dusky streaks on the flanks, and narrow paler tail tips. Lacks the big white wing and tail flashes of Northern Mockingbird, which also occurs on the island.
识别特征
The Socorro mockingbird (Mimus graysoni) is an endangered mockingbird endemic to Socorro Island in Mexico's Revillagigedo Islands. The specific epithet commemorates the American ornithologist Andrew Jackson Grayson. Mimus graysoni shows its close relationship to the northern and tropical mockingbirds rather subtly. It is a much stouter bird, resembling some thrashers in habitus. It also has a distinct juvenile plumage, more rufous above and has a heavy pattern, especially below. This uncannily resembles, e.g., the gray thrasher (Toxostoma cinereum) from Baja California, but is apparently a case of convergent evolution.
分类信息
This is a rather distinct Mimus mockingbird and was for some time placed into a distinct genus, Mimodes. This was revealed to be incorrect based on analysis of mtDNA NADH dehydrogenase subunit 2 sequences.<p>Rather, the present species is closely related to the northern and tropical mockingbirds. Its distinctiveness is the result of the strong selective pressure on its island home, which enforced the evolution of conspicuous adaptational autapomorphies. The juvenile plumage might also have been the result of genetic drift enforced maybe by resource partitioning in this aggressive bird. The standard model of molecular clocks cannot be applied for mimids as their rates of mutation seem to vary much over time. While it is the most phenotypically distinctive bird on Socorro, it also has the strongest ecological change from its ancestors; therefore its distinctiveness is not informative except supporting the theory that it is one of the older Socorro endemics.<p>Thus, and because the adaptation to the peculiar conditions on Socorro may even have accelerated not only morphological but also molecular evolution – see also founder effect — it cannot be said with any certainty whether or not among Mimus, the Socorro species is a quite recent island offshoot of either of the mainland species. In any case, the three taxa are very close relatives.
- 学名
- Mimus graysoni
- 命名信息
- (Lawrence, 1871)
- 目
- Passeriformes
- 科
- Mimidae
- 属
- Mimus
分布与栖息地
- 迁徙
- Resident species
行为
Migration pattern: Resident species.
保护状况
Population trend: stable.
- 种群趋势
- stable
照片
分布
鸟叫声
其他鸟类
Japanese Scops-Owl
Otus semitorques
Small grayish owl with prominent ear tufts and dark red eyes, found in lowland and hill forests, forest edges, parks, and gardens. Ryukyu Scops-Owl and Oriental Scops-Owl both have yellow to orangish eyes; Japanese has a more complete collar and more contrastingly pale facial disc. Vocalizations include a variety of meowing, croaking, and barking calls, as well as shrill screeches.
White-bellied Fantail
Rhipidura euryura
As the name indicates, a dark gray fantail with a white belly. Also note white eyebrow and white-tipped tail feathers. Malaysian Pied Fantail is somewhat similar, but has a bright white throat, is darker overall, and favors different habitats. Inhabits foothill and montane forests, where it is generally uncommon. Forages actively, often associating with mixed flocks, moving through the lower and middle levels of forest. Often in dense, tangled vegetation. Song is a jumble of high whistled notes. Calls include a quiet “ch’reer” and pips.
Hoary-headed Grebe
Poliocephalus poliocephalus
Small ducklike bird that rides low in the water. In breeding plumage note distinctive streaked head and pale neck. In non-breeding plumage it is much paler, with the dark cap extending to just below the eye (compare with Australasian Grebe). Can form very large flocks; typically found on ponds and lakes, including estuaries.
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