Lake Duck
Oxyura vittata
Fairly common locally on lakes with surrounding reeds and wetlands with open water; spends much time sleeping. The lowland counterpart to the very similar Andean Duck; the two species may occur together in a few places, but Andean Duck is rare in lowlands, where Lake Duck is the default species. Lake Duck has a squarer head and a slightly longer tail than Andean Duck, but male plumages are very similar. Female Lake Duck often has more contrasting and paler markings with pale barring on sides and bolder stripes on the face than Andean Duck.
识别特征
The lake duck grows to 36–46 centimetres (14–18 in). Females weigh 510–700 grams (18–25 oz) and males 600–850 grams (21–30 oz). Males can be distinguished from Andean duck (Oxyura ferruginea), a similar species, by being smaller and having a flatter head.<p>The lake duck holds the Guinness World Record for having the largest avian reproductive organ, from a specimen in Córdoba, Argentina that had a penis measuring 42.5 centimetres (16.7 in). It also has the longest penis of any vertebrate in relation to body length. The penis, which is typically coiled up in flaccid state, can reach about the same length as the animal itself when fully erect, but more commonly is about half the bird's length. It has a soft tip and spiny base. It is theorized that the size of their spiny penises with bristled tips may have evolved in response to competitive pressure in these highly promiscuous birds, removing sperm from previous matings in the manner of a bottle brush.<p>Although most male birds have no penis, ducks have a long corkscrew penis, and the females have a long corkscrew vagina, which spirals in the opposite direction. The males often try to force copulation, but the complex mating geometry allows the females to retain control—most forced copulations do not result in successful fertilization.
分类信息
- 学名
- Oxyura vittata
- 命名信息
- (Philippi, 1860)
- 目
- Anseriformes
- 科
- Anatidae
- 属
- Oxyura
分布与栖息地
The lake duck is a partially migratory species. It lives in bodies of freshwater with large amounts of vegetation, such as wetlands and lakes. It is very widespread, naturally occurring in Argentina, Brazil, Chile, Paraguay, and Uruguay, and having been introduced to the Falkland Islands. It has a stable population of 6,700–67,000, with no major threats. As of 2016, it is listed as a species of least concern on the IUCN Red List.
- 迁徙
- Complete migrants
行为
Little is known about the lake duck's diet, but it is believed to consist of small invertebrates, seeds, and plant remains. The breeding season varies between countries, occurring from October to January in Argentina. Males produce popping noises and "mechanical rustling noises" for display.
保护状况
- 种群趋势
- stable
照片
分布
鸟叫声
其他鸟类
Tepui Swift
Streptoprocne phelpsi
Large, dark swift of tepui highlands. Note generally dark appearance, broad wings, and forked tail. If seen in good light, chestnut collar of adult is diagnostic; otherwise this species may be difficult to distinguish from other large swifts, especially at a distance. Found around the tepuis and down to at least 400 meters in the surrounding region. Forages high for insects, often with other swifts; may descend to just above treetop level to feed on swarms of emerging winged ants and termites. In poor light, most similar to White-chinned Swift but has more deeply forked tail.
Ochraceous Wren
Troglodytes ochraceus
Tiny short-tailed wren, plain warm brown with brighter buffy face and bold buffy eyebrow. Found in highland forests, where it can be seen sneaking up tree trunks and through vine tangles in search of insects. Often follows mixed feeding flocks. Similar to House Wren, but note warmer color and eyebrow. Listen for song, a high-pitched musical jumble of tinkling notes and short trills.
African Swamphen
Porphyrio madagascariensis
When seen in good light, shows spectacular purple, green, and pale blue coloration. In dull light, looks dark, but still shows red bill and feet and white undertail. Found in freshwater and brackish wetlands with thick vegetation, mainly at low and middle elevations. Gives a loud trumpeting call. Coloration similar to Allen’s Gallinule, but chunkier and larger, with a much larger bill. Larger than Eurasian Moorhen, with brighter coloration, red legs, and no yellow tip to the bill.
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