Coscoroba Swan
Coscoroba coscoroba
A distinctive white swan with a bright, rather ducklike bill. The black wingtips are usually concealed when swimming. Most likely to be confused with white domestic waterfowl. Fairly common but sometimes local on lakes, slow-moving rivers, wetlands with open water, estuaries, and inshore coastal waters. Often in groups and associates readily with Black-necked Swan. Cygnets are dirty brownish with a black face mask, but young look much like adults within a month or two after hatching. Name comes from slightly gruff, honking “kós-ko roa” call.
识别特征
The coscoroba swan is a medium-large sized waterfowl, but smaller than the true swans, at 90 to 115 cm (35 to 45 in) long with a wingspan of about 155 cm (61 in). Males weigh 3.8 to 5.4 kg (8.4 to 12 lb) and females 3.1 to 4.5 kg (6.8 to 9.9 lb). Their appearance is considered to be slightly unusual, being intermediate between that of geese and true swans. They have completely feathered faces—unusual for true swans—and their feet are located directly under their bodies, enabling the coscoroba swan to walk more efficiently than the “waddling” of most waterfowl. Physically, coscoroba swans have been compared to the American Pekin duck, albeit larger and with darker, redder bills and feet (Pekin ducks have bright orange bills and feet). The sexes have the same plumage; upon hatching, the chicks have blue-grey bills and feet and black striping running down the length of their bodies (to aid in camouflage from predators), with this eventually fading by about eight months of age. The adults are completely white, except for black tips to the outer six primary feathers, though this black is often barely visible on the closed wing unless the bird is in flight.
分类信息
The coscoroba swan's placement within the family Anatidae is not fully agreed upon, with a 2014 genetic study positing a phylogenetic relationship between this species and the Cape Barren goose (Cereopsis novaehollandiae). BirdLife International's Handbook of the Birds of the World has adopted this approach and places the coscoroba swan and Cape Barren goose together in the tribe Cereopsini, which it places as basal to Cygnus and all other geese. However, the South American Classification Committee of the American Ornithological Society, the International Ornithological Committee (IOC), and the Clements taxonomy treat the Cape Barren goose as basal to other geese, which themselves precede the coscoroba and other swans in a linear sequence. Even those three systems differ, with the IOC placing the coscoroba before Cygnus and the other two after it in their lists.<p>The coscoroba swan is the only member of the genus Coscoroba and has no subspecies.
- 学名
- Coscoroba coscoroba
- 命名信息
- (Molina, 1782)
- 目
- Anseriformes
- 科
- Anatidae
- 属
- Coscoroba
分布与栖息地
The coscoroba swan is a year-round resident of central Argentina and along the Uruguay-southern Brazil coast. It also breeds but does not winter from southern Chile and Argentina south to Tierra del Fuego and occasionally to the Falkland Islands. In winter its range extends north to central Chile, northern Argentina, Paraguay, Uruguay, and southern Brazil. It has been recorded as a vagrant in Bolivia and at several locations in Brazil north of its usual limit. The coscoroba swan inhabits well-vegetated lagoons, freshwater swamps, and sometimes human-made reservoirs. It is mainly a bird of the lowlands, though there are scattered records as high as 1,300 m (4,300 ft) and at least one at 2,000 m (6,600 ft).
- 迁徙
- Complete migrants
行为
The coscoroba swan's diet has not been studied in detail, but it apparently feeds on aquatic and some terrestrial plants, small aquatic invertebrates, and small fish. It forages mainly while swimming or wading in shallow water and in contrast to other swans seldom upends. It also grazes on land. It often feeds with black-necked swans (Cygnus melanocoryphus).<p>The coscoroba swan breeds in the local spring, which is May to October in northern Argentina, July to December in Chile, and July and August in southern Brazil. The species forms long-term pair bonds. Its nest is a mound of vegetation lined with soft grass constructed by both members of a pair on a small islet, partially floating in a reedbed or long grass close to water. The clutch size is four to nine oval eggs that weigh about 167 g (5.9 oz) with dimensions of about 88 by 60 mm (3.5 by 2.4 in). Males guard females during the incubation period of about 35 days. Both parents care for the young through fledging at 14 weeks and beyond, sometimes until they are a year old. In captivity, coscoroba swans can live 20 years.<p>The coscoroba swan makes an onomatopoeic "cos-cor-oo", usually as a threat to intruders. They also make a "monosyllabic hooting note" as a contact call between mates. Immature birds make "loud chirps and trills".
保护状况
- 种群趋势
- stable
照片
分布
鸟叫声
其他鸟类
North Island Kokako
Callaeas wilsoni
Large songbird confined to a few scattered forests in the northern half of the North Island of New Zealand, and some offshore island sanctuaries where predator control is undertaken. Adults have a slate blue-gray body with vibrant cerulean wattles and a distinct black mask. Juvenile has smaller, pale pink wattles and a smaller face mask. Note the long downcurved tail and long legs, which help them bound around treetops with small wing flaps. Prefers not to fly but can glide for a few hundred meters when needed. Heard before seen at dawn; its unique, haunting song is composed of rich, sustained, organ-like notes. Often sings from a high perch and flaps its wings as it calls.
Cape White-eye
Zosterops virens
A small, active, mostly yellow-green warbler-like bird with an obvious white eye-ring. The two races have different breast and belly coloration: gray in the south and greenish in the north. Pairs are common in all habitats, where they form a strong component of mixed-species flocks. A sweet, rolling reedy warble that is disjointed and rambling is often the first sign that they are around. The Cape White-eye is similar to the Yellow White-eye, which has more lemon-colored underparts, and the Orange River White-eye, which has peach-colored flanks.
White-winged Coot
Fulica leucoptera
Fairly common to uncommon coot, mainly in lowlands. Found on fresh to brackish ponds and lakes and wetlands with open water. Feeds mainly while swimming, often farther out on open water than other coots. Bill pattern diagnostic: rather small rounded forehead shield is bright yellow to deep orange, always brighter than the pale yellow bill. Named for narrow white trailing edge to wings, that are rarely visible. Juvenile sooty gray with whitish face and foreneck. Often occurs with Red-gartered Coots.
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