Comb Duck
Sarkidiornis sylvicola
Large bicolored waterbird. Both sexes are iridescent purplish-green above with a white breast. Males have a large black lump on the bill, dark flanks and whitish belly, whereas females have a plain bill and gray flanks. Note all dark wings. Occurs throughout much of South America, rarely straying north to Costa Rica. Found in freshwater rivers, lakes, and marshes where it is usually uncommon. Normally silent.
识别特征
This common species is unmistakable. It is one of the largest species of duck. Length can range from 56 to 76 cm (22 to 30 in), wingspan ranges from 116 to 145 cm (46 to 57 in) and weight from 1.03 to 2.9 kg (2.3 to 6.4 lb). Adults have a white head freckled with dark spots, and a pure white neck and underparts. The upperparts are glossy blue-black upperparts, with bluish and greenish iridescence especially prominent on the secondaries (lower arm feathers). The male is much larger than the female, and has a large black knob on the bill.<p>If seen at a distance, immature comb ducks can also be mistaken for a fulvous whistling duck (Dendrocygna bicolor). However, knob-billed ducks in immature plumage are rarely seen without adults nearby and thus they are usually easily identified, too.
分类信息
Uncertainty surrounds the correct systematic placement of this species. Initially, it was placed in the dabbling duck subfamily Anatinae. Later, it was assigned to the "perching ducks", a paraphyletic assemblage of waterfowl most of which are intermediate between dabbling ducks and shelducks. As the "perching ducks" were split up, the comb duck was moved to the Tadorninae or shelduck subfamily.<p>Analysis of mtDNA sequences of the cytochrome b and NADH dehydrogenase subunit 2 genes, however, suggests that it is a quite basal member of the Anatidae, vindicating the earliest placement, but its closest living relatives cannot be resolved to satisfaction without further study.
- 学名
- Sarkidiornis sylvicola
- 命名信息
- Ihering, HFA & Ihering, R, 1907
- 目
- Anseriformes
- 科
- Anatidae
- 属
- Sarkidiornis
分布与栖息地
- 迁徙
- Complete migrants
行为
It breeds in still freshwater swamps and lakes in the tropics. It is largely resident, apart from dispersion in the wet season.<p>This duck feeds on vegetation by grazing or dabbling and to a lesser extent on small fish, invertebrates, and seeds. It can become a problem to rice farmers. Knob-billed ducks often perch in trees. They are typically seen in flocks, small in the wet season, up to 100 in the dry season. Sometimes they separate according to sex.<p>Comb ducks nest mainly in tree holes, also in tall grass. They line their nests with reeds, grass, or feathers, but not down.<p>Males may have two mates at once or up to five in succession. They defend the females and young, but not the nest sites. Unmated males perch in trees and wait for opportunities to mate.<p>Females lay seven to 15 yellowish-white eggs. Several females may lay in a single "dump nest" containing up to 50 eggs.
保护状况
- 种群趋势
- declining
照片
分布
其他鸟类
Lettered Aracari
Pteroglossus inscriptus
Small toucan found across southern Amazonia. Unlikely to be confused in range. Essentially dark above with entirely yellow underparts; note the bare blue skin above the eye. Named for the squiggly dark markings on the bill. Typically found in pairs or small groups in the canopy of lowland forest and edges, up into the foothills of the Andes. Often seen perched conspicuously on a snag, or foraging in a fruiting tree.
Malherbe's Parakeet
Cyanoramphus malherbi
A small, green, long-tailed parakeet endemic to New Zealand. Note the distinct lemon-yellow crown and the thin orange band extending from the base of the beak to each red eye. Juveniles are a duller color and their orange band and crown may be absent. A critically endangered bird now restricted to three beech forest valleys in inland Canterbury and several offshore island sanctuaries. Usually very quiet and challenging to see. Listen for its loud, brief chatter call to give away its location. When pairs are together, softer contact calls can be heard. Forms small flocks in autumn and winter. Smaller size and lack of crimson frontal band and rump patches distinguish Malherbe’s from Yellow-crowned Parakeet. Juvenile Yellow-crowned Parakeet can confuse identification, and calls of the two species can be challenging to differentiate.
Singing Parrot
Geoffroyus heteroclitus
A mostly green medium-sized parrot with a contrasting head, gray in females and yellow in males. Shows a blue underwing in flight. Inhabits lowland forest edge, including coconut plantations, parks, and gardens, up to at least 1750 meters of elevation. Bulkier than Cardinal, White-naped, Yellow-bibbed, and Purple-bellied Lories, with slower wingbeats, and lacks the mostly red color of those species. The similar Eclectus Parrot is larger with a bigger bill, and male is also green but has a red underwing. Singing Parrot’s voice includes a wide variety of harsh cries and a whistling bell-like song.
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