Olrog's Gull
Larus atlanticus
Large, dark-backed gull with a broad black band on a white tail. Breeding adults have mostly clean white bodies with black backs and wings. In the nonbreeding season, adults have a black hood and a broken white eye-ring. Immatures are very distinctive, with mottled gray-brown backs and brown breasts and heads with a white patch around the bill. Usually seen on the immediate coast, where it mostly eats crabs. During the austral winter, some migrate farther north.
识别特征
Olrog's gull is a large gull with a white head, neck, rump, breast, and belly. The back and wings are black except for a white trailing edge to the wings. The tail is white with a broad black band at the back. The beak is yellow with a black band and red tip. The eyes are brown with a red orbital ring and the legs and feet are dull yellow. The length of this gull is 50 to 60 cm (20 to 24 in) and it has a wingspan of 130 to 140 cm (51 to 55 in). Males are a little larger than females. Juveniles have black heads and brownish plumage.
分类信息
- 学名
- Larus atlanticus
- 命名信息
- Olrog, 1958
- 目
- Charadriiformes
- 科
- Laridae
- 属
- Larus
分布与栖息地
Olrog's gull is native to the Atlantic coast of Argentina, Uruguay, and southern Brazil. It breeds at a very limited number of colonies between 38.49° and 45.11°S, about two-thirds of which are in the estuary of the Bahia Blanca River. It nests on the ground just above high-water mark, on low islands and islets. At other times, it is to be seen on rocky coasts, harbours, beaches, coastal lagoons, brackish water, and estuaries.
- 繁殖区
- SA : coastal s Buenos Aires and Chubut provinces (ne, ec Argentina)
- 非繁殖区
- some move to coasts of se Brazil
- 迁徙
- Complete migrants
行为
During the breeding season, Olrog's gull feeds largely on crabs, which are picked up from the exposed shore or the seabed while walking or swimming, or dipping under the surface of shallow water. This particular diet gives the gull its name in its native range: gaviota cangrejera, or crab-eater gull.<p>At other times of year, it supplements its crab diet with bivalve molluscs and polychaete worms. Other prey items include insects, gastropod molluscs, fish, and fish waste, and the birds sometimes visit sewage outlets and refuse dumps.<p>Breeding starts in September and October. Olrog's gull is monogamous and nests in dense colonies. The nest is on rock, sand, or shingle and is usually lined with vegetation, but sometimes with seaweed, feathers, shells or bones. Two or three olive-brown eggs with brown splotches are laid and the incubation period is about 30 days. Fledging takes place between November and January according to the location of the colony.
保护状况
- 种群趋势
- stable
照片
分布
鸟叫声
其他鸟类
Olive Honeyeater
Lichmera argentauris
A nondescript sparrow-sized songbird with a slender, downcurved bill. Entirely olive-green above and uniform pale gray below, but note head pattern, which includes a prominent whitish smudge on the cheeks and dull bare skin below the eye. Juvenile has a pink facial patch. Singles, pairs, or groups inhabit scrubland, wooded areas, and coconut plantations in lowlands. Confined to islets in the Moluccas and to West Papua, where it is readily identified by its head pattern. Harsh, squeaky vocalizations include “tchew” and “grrt” notes and “chi-witchoo” or “witch-oo” phrases.
Barred Long-tailed Cuckoo
Cercococcyx montanus
Rufous-brown, heavily barred cuckoo with an unusually long tail. There can be a wash of rufous on the throat and/or breast. Found in forest and thick woodland, including some miombo. Shy and retiring, and most easily found by voice. There are two main vocalizations; one is a long series of slurred “tseeeuw” calls which become more empatic. This sometimes leads into the second call type, which is a four-noted “toot tweet tow tweet.” Similar to other long-tailed cuckoos, but the adult is easily separated by the rufous barring on the upperparts.
Striated Laughingthrush
Grammatoptila striata
With its short bill and loose, bushy crest, this laughingthrush resembles a dark, rather unmarked barwing. Brown overall with pencil-thin white lines all over the body. Crest is dark brown, and wings are dull rufous. Inhabits forests and adjoining areas with dense undergrowth in the Himalayan foothills. Like many other laughingthrushes, highly social and often found in flocks, which keep in contact with calls ranging from harsh screeches to hooting. Often gives a series of repeated loud, upslurred notes.
开始您的观鸟之旅
在户外识别鸟类，并在下一次观察时随手查阅鸟类图鉴。