Swamp Harrier
Circus approximans
Long-legged medium-sized raptor with long narrow wings. Adult has varied plumage, but note diagnostic prominent white rump. Juvenile is darker below. Flies slowly and low over open habitats with wings held in shallow V shape. Breeds in reed-beds, and occurs mainly in swamps and wetlands.
识别特征
The swamp harrier is largely dark brown, becoming lighter with age, and has a distinct white rump. It hunts by flying slowly, low to the ground, on upswept wings. The body length is 48 to 62 cm (19 to 24.5 in), and the wingspan is 118 to 145 cm (3 ft 10 in to 4 ft 9 in). The recorded weights of adults range from 580 to 1,100 g (1.28 to 2.43 lb). Females are significantly larger than the males. In New Zealand, 54 males averaged 640 g (1.41 lb) and 66 females averaged 870 g (1.92 lb). Going on mean weights and linear measurements, the swamp harrier may be by a slight margin the largest extant species of harrier but it is only marginally larger than some other species, like the marsh harriers and the Réunion harrier.
分类信息
- 学名
- Circus approximans
- 命名信息
- Peale, 1849
- 目
- Accipitriformes
- 科
- Accipitridae
- 属
- Circus
分布与栖息地
The swamp harrier is widespread through Australasia and many islands in the south-west Pacific region, including much of Australia (except the arid region), New Zealand (where it is common in open country), Fiji, Vanuatu, New Caledonia and as stragglers on some subantarctic islands. It is usually found in wetlands and well-watered open country.<p>The swamp harrier only became established in New Zealand within the last few hundred years, after lowland forests were extensively cleared by the first Polynesian settlers. It is absent from the fossil record. According to archeological and genetic research, humans arrived in New Zealand no earlier than about 1280, with at least the main settlement period between about 1320 and 1350, consistent with evidence based on genealogical traditions. The Eyles's harrier (Circus teauteensis), a larger harrier species endemic to New Zealand, became extinct after human settlement. All swamp harrier remains from New Zealand that have been studied in detail are some 1000 years old at most, meaning that they post-date human settlement. There is no evidence for widespread coexistence of swamp and Eyles's harriers in New Zealand. Apparently, despite their considerable differences, the two harriers were still ecologically similar enough to competitively exclude one another, and only when the endemic Eyles's harrier became extinct could the swamp harrier become established.<p>The swamp harrier has benefited from European settlement, and is now very common, especially in open farmland.
- 繁殖区
- AU : Australia (except sc), North, South, Stewart and Chatham is. (e of South I.; New Zealand), Vanuatu, New Caledonia including Loyalty Is., to Fiji and Tonga (sw, sc Polynesia)
- 非繁殖区
- to Trans-Fly (sc New Guinea) and Kermadec Is. (ne of North I., New Zealand)
- 迁徙
- Complete migrants
行为
Common enemies of harriers are Australian magpies, masked lapwings which dive bomb and European starlings which mob individuals. They have been known to kill the young of New Zealand falcons and have also been heavily blamed and persecuted for killing chickens, pheasants and ducklings. Swamp harriers are the only bird of prey used for falconry in New Zealand. The quarry is usually pūkeko and young rabbits.<p>The swamp harrier mainly feeds on ground birds and waterbirds, rabbits and other small mammals, reptiles, frogs, and fish. During the winter months harriers feed to a large extent on carrion, including roadkill, frequently falling victim to vehicles themselves.<p>This species nests on the ground, often in wetlands, on a mound in reeds or other dense vegetation. In some districts they nest in fields of oats or barley. The clutch size may range from two to seven, but is usually three or four. The incubation period is 31 to 34 days, and is carried out by the female alone. Chicks are fed by both parents, are fully feathered by 28 days and fledging about 45 days after hatching.
保护状况
- 种群趋势
- stable
照片
分布
鸟叫声
其他鸟类
Ashy Starling
Lamprotornis unicolor
An unusual slim brownish-gray starling with a long, narrow tail. The eye is pale, and there is a greenish gloss on the back and tail in fresh plumage. A Tanzanian endemic that is found in moderately moist savanna and woodland, usually in small flocks, often feeding on the ground. Rüppell’s Starling also has a long tail, but Ashy is easily separated by being gray rather than glossy blue-black. Makes quiet mewing, rasping, and chattering calls.
White-throated Caracara
Daptrius albogularis
Uncommon in southern Andes; range does not overlap with Mountain Caracara. Favors open habitats above treeline, but also ranges lower to scavenge at dumps and in farmland with open trees. Often associates with Chimango and Crested Caracaras at the dump outside Ushuaia, Argentina. Sails, soars, and tumbles easily on updrafts. Adult is handsome and strikingly patterned black-and-white with creamy white underparts and a bold white tail tip. Juvenile is rather similar to smaller Chimango Caracara, but distinguished by black (not pale) bill.
Mallard
Anas platyrhynchos
A large duck, generally common and familiar within its extensive range. Males are distinctive with iridescent green head, yellow bill, chestnut breast, and gray body. Females are mottled brown with orange and black splotches on the bill. Found anywhere with water, including city parks, backyard creeks, and various wetland habitats. Often in flocks, and frequently mixes with other duck species. In North America, females can be tricky to distinguish from American Black Duck, Mottled Duck, and Mexican Duck where ranges overlap. Those species are all darker-bodied than Mallard. A good view of the wing can be helpful, too: white wingbars on the leading and trailing edges of the blue wing patch are bolder on Mallard. Frequently hybridizes with those species, which can be even more confusing. Any bird with extensive white in the tail or curled feathers above the tail has some Mallard genes.
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