| 翻訳と辞書 |
Razorbill
The razorbill (''Alca torda'') is a colonial seabird that only comes to land in order to breed. This agile bird chooses one partner for life; females lay one egg per year. Razorbills nest along coastal cliffs in enclosed or slightly exposed crevices. The parents spend equal amounts of time incubating. Once the chick has hatched, the parents take turns foraging for their young and sometimes fly long distances before finding prey.
The razorbill is primarily black with a white underside. The male and female are identical in plumage; however, males are generally larger than females. In 1918, the razorbill was protected in the United States by the Migratory Bird Treaty Act. Presently, the major threat for the population is the destruction of breeding sites.
==Description==
The razorbill has white underparts and a black head, neck, back and feet during breeding season. A thin white line also extends from the eyes to the end of the bill. Its head is darker than that of a common murre. During the nonbreeding season, the throat and face behind the eye become white, and the white line on the face becomes less prominent.〔 The thick black bill has a blunt end. It is large for an alcid and its mean weight ranges from .〔 The female and male adults are very much alike, having only small differences such as wing length. The wing length of adult males ranges from while that of females ranges from .〔 This species has a horizontal stance and the tail feathers are slightly longer in the center in comparison to other alcids. This makes the razorbill have a distinctly long tail which is not common for an auk. Their mating system is female-enforced monogamy; the razorbill chooses one partner for life. It nests in open or hidden crevices among cliffs and boulders. It is a colonial breeder and only comes to land to breed. The annual survival rate of the razorbill is between 89-95%.〔 Though the razorbill's average lifespan is roughly 13 years, a bird ringed in the UK in 1967 has survived for at least 41 years — a record for the species.〔
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
■ウィキペディアで「Razorbill」の詳細全文を読む
スポンサード リンク
| 翻訳と辞書 : 翻訳のためのインターネットリソース |
Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.
|
|