Kelp Gull
Larus dominicanus
Large dark-backed gull. Few similar species in much of its range. Usually coastal. Adults have black backs and wings with very little white in the flight feathers. The bill is very strong and robust and the legs are greenish-yellow. Juveniles have a dark brown back mottled with white, a black bill, and a dark band on the tail.
识别特征
The kelp gull superficially resembles two gulls from further north in the Atlantic Ocean, the lesser black-backed gull and the great black-backed gull and is intermediate in size between these two species. This species ranges from 54 to 65 cm (21 to 26 in) in total length, from 128 to 142 cm (50 to 56 in) in wingspan and from 540 to 1,390 g (1.19 to 3.06 lb) in weight. Adult males and females weigh on average 1,000 g (2.2 lb) and 900 g (2.0 lb) respectively. Among standard measurements, the wing chord is 37.3 to 44.8 cm (14.7 to 17.6 in), the bill is 4.4 to 5.9 cm (1.7 to 2.3 in) and the tarsus is 5.3 to 7.5 cm (2.1 to 3.0 in). The adult kelp gull has black upper parts and wings. The head, underparts, tail, and the small "mirrors" at the wing tips are white. The bill is yellow with a red spot, and the legs are greenish-yellow (brighter and yellower when breeding, duller and greener when not breeding). The call is a strident ki-och. Juveniles have dull legs, a black bill, a dark band in the tail, and an overall grey-brown plumage densely edged whitish, but they rapidly get a pale base to the bill and largely white head and underparts. They take three or four years to reach maturity.
分类信息
- 学名
- Larus dominicanus
- 命名信息
- Lichtenstein, MHC, 1823
- 目
- Charadriiformes
- 科
- Laridae
- 属
- Larus
分布与栖息地
- 迁徙
- Resident species
行为
Kelp gulls are omnivores like most Larus gulls, and they will scavenge as well as seek suitable small prey. They gather on landfills and a sharp increase in population is therefore considered as an indicator for a degraded environment. Kelp gulls have been observed feeding on living right whales since at least 1996. The kelp gull uses its powerful beak to peck down centimetres into the skin and blubber, often leaving the whales with large open sores, some of which have been observed to be half a meter in diameter. This predatory behavior has been documented in Argentinian waters. At rocky sites along the Southern African coast, such as at Boulders Beach in Cape Town, kelp gulls (Larus dominicanus vetula) can be seen picking up shellfish and repeatedly flying up several meters and dropping them onto the rocks below in order to break them open. They have also been reported pecking the eyes out of seal pups on the coast of Namibia before attacking the blind seals in a group.<p>The nest is a shallow depression on the ground lined with vegetation and feathers. The female usually lays 2 or 3 eggs. Both parents feed the young birds.
保护状况
- 种群趋势
- rising
照片
分布
鸟叫声
其他鸟类
Moluccan Swiftlet
Aerodramus infuscatus
A small dark brown swift of with a narrow whitish rump band; endemic to Sulawesi and the Moluccas. Includes the former Seram, Halmahera, and Sulawesi Swiftlets. Upperparts are darker brown than underparts. Flies acrobatically over a wide variety of habitats and elevations, often in flocks with other swiftlet species. Drab plumage and fast-flying habits can make this species difficult to distinguish from other small swifts; note pale, well-defined rump band (absent in Glossy Swiftlet, absent or poorly-defined in Uniform Swiftlet, and bright white in House Swift). Chitters squeakily.
Biscutate Swift
Streptoprocne biscutata
Large swift with a dark body, long scythe-shaped wings and a square-tipped tail. Resembles White-collared Swift, but has an incomplete and misaligned white collar like a white bib and may have a paler face. Roost and nest in caves and waterfalls where it returns at dusk after foraging over the surrounding landscape.
Tawny Fish-Owl
Ketupa flavipes
A large brown owl with wide yellow eyes and sideways-drooping ear tufts; rich tawny brown plumage with black mottling unique in its range. Always found in close proximity to rivers or lakes, usually roosting in dense waterside groves by day. Hunts fish from a low perch at dusk and at night. Hunting birds are seldom observed, as they hunt from tangles and other dense vegetation. Other horned owls in range are either much smaller (Long-eared Owl, scops-owls) or much larger (Eurasian Eagle-Owl). Pairs duet, giving 2-3 deep hoots; younger birds beg with higher-pitched screeching calls.
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