Glaucous-winged Gull
Larus glaucescens
Large, stocky gull of the North Pacific. Generally fairly pale and uniform-looking; at all ages, note wingtips and back are approximately the same color. Takes four years for immatures to progress from mostly brown to fully white and gray adult plumage; intermediate plumages are often mottled and messy. Most immatures look frosty grayish-brown with smooth patterning. Found in coastal areas, including beaches, mudflats, and even city parks. Identification is complicated by frequent hybridization with Western, Herring, and Glaucous Gulls in various parts of range. Pure birds can be difficult to find and identify with certainty, and many intermediate birds are best left unidentified.
识别特征
This gull is a large bird, being close in size and shape to the closely related Western gull (L. occidentalis). It measures 50–68 cm (20–27 in) in length and 120–150 cm (47–59 in) in wingspan, with a body mass of 730–1,690 g (1.61–3.73 lb). It weighs around 1,010 g (2.23 lb) on average. Among standard measurements, the wing chord is 39.2 to 48 cm (15.4 to 18.9 in), the bill is 4.6 to 6.4 cm (1.8 to 2.5 in) and the tarsus is 5.8 to 7.8 cm (2.3 to 3.1 in). It has a white head, neck, breast, and belly, a white tail. The silver-gray wings and back form the mantle, which is darker than that of the Glaucous gull and paler than the Herring gull and Western Gull. The primary flight feathers (wingtips) are grey, usually the same shade as the mantle. Its legs are pink and the beak is yellow with a red subterminal spot (the spot near the end of the bill that chicks peck in order to stimulate regurgitative feeding). The irises are typically dark, and surrounded by pink orbital skin. The forehead is somewhat flat. During the winter, the head and nape is darker with a varied smudged or mottled pattern, and the bill colour becomes duller, often with dark markings near the tip. Young birds are brown or gray with black beaks, and take four years to reach adult plumage.
分类信息
Genus: Larus; Family: Laridae; Order: Charadriiformes.
- 学名
- Larus glaucescens
- 命名信息
- Naumann, JF, 1840
- 目
- Charadriiformes
- 科
- Laridae
- 属
- Larus
分布与栖息地
Breeding range: PAL, NA : coastal North Pacific in e Siberia, Kamchatka, Kuril and Commander is. (e Russia); Aleutian and Pribilof is., sw Alaska mainland to n Washington. Non-breeding range: to Japan and California.
- 繁殖区
- PAL, NA : coastal North Pacific in e Siberia, Kamchatka, Kuril and Commander is. (e Russia); Aleutian and Pribilof is., sw Alaska mainland to n Washington
- 非繁殖区
- to Japan and California
- 迁徙
- Complete migrants
行为
Migration pattern: Complete migrants.
保护状况
Population trend: rising.
- 种群趋势
- rising
照片
分布
鸟叫声
其他鸟类
Ochre-lored Flatbill
Tolmomyias flaviventris
Small, yellowish-olive flycatcher that ranges mainly in northern and eastern South America as well eastern Panama. Distinguishing features include its yellow throat and breast, orange face, thick wingbars, and wide bill. Similar to Olive-faced Flycatcher, which used to be considered the same species and called Yellow-breasted Flycatcher. Note their different ranges, which mostly do not overlap. Ochre-lored Flycatcher has a brighter face with a hint of orange, more distinct wingbars, and has a different voice. Its most common call is a piercing whistle given alone or in a slow series. Occasionally also gives well-spaced rasping calls. Inhabits secondary forest and light woodland, usually avoiding the interior of mature forest.
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Large finch with a long spiky tail. Mostly gray with olive-green wings and tail. Note the bicolored bill (dark above and yellow-orange below) and the broken white eye-ring. Inhabits higher elevations, in dry scrub, rocky areas, and grassy fields with scattered palms. Sings a high, thin “tsi, tsoweee,” repeated continually.
Javan Owlet
Glaucidium castanopterum
Chunky small owl with a big rounded head. Note finely barred head, bright chestnut back and wings, and white underparts marked with long brown streaks. The only owlet on Java; shape and coloration eliminate any scops-owl. Unlike Collared Owlet, this is a primarily nocturnal species, only rarely remaining active through the day. Inhabits forest and forest edge from lowlands up into foothills. Song is a barbet-like series of trilling barks which accelerates rapidly before ending suddenly.
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