White Tern
Gygis alba
A medium-sized tern with entirely white plumage, a slightly forked tail, and glittering inky pools for eyes. The bill is black with a blue base. Graceful and buoyant in flight. Breeds in trees and both natural and artificial ledges on coral islands. Sometimes flies very high in pairs or trios. Often seen offshore from boats, though most frequently encountered foraging over inshore waters.
识别特征
The white tern has a wingspan of 76–87 cm (30–34 in). It has white plumage and a long black bill. Nesting on coral islands, usually on trees with small branches but also on rocky ledges and on man-made structures, the white tern feeds on small fish which it catches by plunge diving. Giant tortoises have been observed to hunt the bird on Fregate Island in the Seychelles.
分类信息
The white tern was first formally described by the Swedish naturalist Anders Sparrman in 1786 under the binomial name Sterna alba. The genus Gygis was introduced by the German zoologist Johann Georg Wagler in 1832. The name Gygis is from the Ancient Greek guges for a mythical bird and the specific alba is Latin for "white".<p>Molecular phylogenetic studies have shown that the white tern is more closely related to the noddies than it is to the other terns. This implies that "white noddy" would be a more appropriate English name.<p>The white tern has the following recognized subspecies:<p>Some authors have postulated that there may be three species of Gygis: Gygis alba, in the Atlantic Ocean, and Gygis candida and Gygis microrhyncha, both in the Pacific.
- 学名
- Gygis alba
- 命名信息
- (Sparrman, 1786)
- 目
- Charadriiformes
- 科
- Laridae
- 属
- Gygis
分布与栖息地
The white tern ranges widely across the Pacific Ocean from the coasts of Chile and Colombia to New Zealand and along the eastern and southern coasts of Asia from China to India, South Maldives, the islands of the Indian Ocean, and the coast of South Africa. Rarely it is also found in Japan, Madagascar, Mexico, and on some islands in the Atlantic Ocean. It is a pelagic and epipelagic bird, living along the coast and moving into wooded areas during the breeding season.
- 繁殖区
- TrO : widespread on tropical and subtropical is. (except Caribbean, n, e Indian Ocean)
- 非繁殖区
- tropical seas
- 迁徙
- Resident species
行为
This species is notable for laying its egg on bare thin branches in a small fork or depression without a nest. This behaviour is unusual for terns, which generally nest on the ground, and even the related tree-nesting black noddy constructs a nest. It is thought that the reason for the absence of nests is the reduction in nest parasites, which in some colonial seabirds can cause the abandonment of an entire colony. In spite of these benefits there are costs associated with tree nesting, as the eggs and chicks are vulnerable to becoming dislodged by heavy winds. For this reason the white tern is also quick to relay should it lose the egg. The newly hatched chicks have well developed feet with which to hang on to their precarious nesting site. It is a long-lived bird, having been recorded living for 42 years.
保护状况
- 种群趋势
- stable
照片
分布
鸟叫声
其他鸟类
Inca Dove
Columbina inca
Essentially a ground dove with a long tail. Pale sandy color with scaly pattern covering entire body, unlike Common Ground Dove. Look for obvious white outer tail feathers and rufous wings in flight. Fairly common from the southwestern U.S. to far western Panama. Found in pairs or small groups in neighborhoods, parks, and scrubby desert habitats. Listen for repeated soft whistled song, sounding like “no hope.” Whirring wingbeats sound almost like a rattlesnake when it takes off.
Double-banded Graytail
Xenerpestes minlosi
Rare but distinctive if seen well. Small bird that is dingy gray above and off-white below with bold white wingbars and a white eyebrow. Actively forages by hitching along branches, often hanging upside-down. Most often seen singly or in pairs in mixed-species flocks, typically in the canopy. Listen for a strange rapid insect-like trill. Occurs in humid lowland forests and edges from eastern Panama to northwest Ecuador.
Souimanga Sunbird
Cinnyris sovimanga
Small, hyperactive bird with a curved bill. Breeding males are colorful, with iridescent upperparts, and a yellow belly in most of the range, and a white belly in southwest Madagascar. Females are much duller, but can be told from female Madagascar Sunbird by their smaller size, smaller bill, and less distinct streaks below. Common in any habitat with woody vegetation. Feeds mainly on nectar, and flits around constantly. The song is a cheerful and explosive jumble of high-pitched notes.
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