Mexican Duck
Anas diazi
Both sexes look like a dark-colored female Mallard. Bill of male is dull yellowish; bill of female is mottled orange and black, like a typical Mallard. In flight, bright white underwings contrast with dark body. Note distinct white stripe in front of iridescent panel on upperwing, compare to Mottled Duck (limited range overlap). Usually in pairs or small flocks; wary in most areas, but in some city parks and urban settings has become fairly tame. In some areas of sw. US, hybridizes with Mallard, producing birds with variably intermediate features.
识别特征
Both sexes of this 51–56 cm length bird resemble a female mallard, but with a slightly darker body. The Mexican duck is mainly brown, with a blue speculum edged with white, obvious in flight or at rest. The male has a brighter yellow bill than the female.
分类信息
Including the Mexican duck in the mallard is a relic from the usual practice of much of the mid-late 20th century, when all North American "mallardines" as well as the Hawaiian and Laysan ducks were included in the mallard proper as subspecies. This was based on the assumption that hybridization, producing fertile offspring, is an indicator of lack of speciation.<p>Rather, in these birds it indicates a fairly recent allopatric radiation, which has not yet established solid barriers against gene flow on the molecular level; mate choice is conferred by cues of behavior and plumage in the mallardine ducks, and this, under natural conditions, has precluded a strong selective pressure towards establishment of genetic incompatibility.
- 学名
- Anas diazi
- 命名信息
- Ridgway, 1886
- 目
- Anseriformes
- 科
- Anatidae
- 属
- Anas
分布与栖息地
Most of the population is resident, but some northern birds migrate south to Mexico in winter. The species also occurs widely, but in limited numbers, in Colorado in all seasons and there are photographs of birds referable to this taxon from Utah, Wyoming, Nebraska, and Montana.<p>It is a bird of most wetlands, including ponds and rivers, and usually feeds by dabbling for plant food or grazing. It nests usually on a river bank, but not always particularly near water.
保护状况
Although a species of least concern, the Mexican duck is undergoing a slow but marked decline due to destruction of habitat and overhunting. It hybridizes with mallards which are better-adapted to utilizing habitat altered by human activity and thus are spreading throughout this range. Concern has been expressed that this combination of factors may ultimately lead to the disappearance of the Mexican duck as a recognizable taxonomic entity (Rhymer & Simberloff 1996, McCracken et al. 2001, Rhymer 2006[dead link]), but fairly limited measures such as wetland preservation and preferential hunting of drake mallards would prevent this. The Mexican duck was listed as endangered species at the United States Fish and Wildlife Service in 1967 but was removed in 1978.
照片
分布
鸟叫声
其他鸟类
Mindanao Bleeding-heart
Gallicolumba crinigera
A medium-sized ground dove of lowland forest floor. Bluish-gray on the head, back, and sides to the chest, with blackish wings, a pale gray shoulder and wingbars, a white throat and sides to the chest, a dingy pinkish belly, and an obvious dark red “bleeding heart” in the center of the chest. Note the scaling on the back. The central eastern race has more gray on the chest. Unlikely to be mistaken if seen well. The only other dove likely to flush from the ground would be Asian Emerald Dove. Voice is a low, upslurred hooting note.
Ash-colored Cuckoo
Coccycua cinerea
Nondescript and retiring cuckoo with a pale ashy-brown back and pale underparts. Note the thin white tail tips and red eyering and iris. An austral migrant. Usually found in dry woodlands, scrub, savannas, gallery forests, and also in the borders of humid moist forests in the nonbreeding season. The song is a series of “cow-w cow-w cow cow” notes.
European Greenfinch
Chloris chloris
Male greenish overall with a rather stout pale pinkish bill, yellow flashes on wing and sides of tail. Female is much drabber, but shares male pattern; especially note the big, dull pinkish bill and yellow wing flash. Inhabits varied wooded and forested habitats, including parks, gardens, and farmland with hedges and scattered trees. Forms flocks in autumn and winter, sometimes moving in more open country. Often visits garden feeders. Listen for chattering song, interspersed with buzzy “dzweeeeee” calls. A Eurasian native, now introduced to southeastern South America, Australia, and New Zealand.
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