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The northern gannet (''Morus bassanus'') is a seabird and the largest member of the gannet family, Sulidae. It has the same colours as the Australasian gannet and is similar in appearance. Nesting in colonies as large as 60,000 pairs on both sides of the north Atlantic this bird undertakes seasonal migrations and is a spectacular high-speed diver. Old names for the northern gannet include solan and solan goose. == Description == Adults are long, weigh and have a wingspan.〔〔 Before fledging, the immature birds (at about 10 weeks of age) can weigh more than . Each wing measures between when outstretched and the beak measures between (measured from the head). The two sexes are a similar size. The plumage of the adults is white with dark wing tips, with colours that range from brown to black. The colour of the head, cheeks and side of the neck depends on the season and the individual; during breeding, the head and neck are brushed in a delicate yellow, although this colouring may not be evident in some individuals.〔 The feathers are waterproof, which allows the birds to spend long periods in water. A water-impermeable secretion produced by a sebaceous gland covers the feathers and the birds spread it across their body using their beak or their head.〔 The eye is light blue, and it is surrounded by bare, black skin, which gives the birds their characteristic facial expression. Fledglings are brown with white wing tips. They have white spots on their head and on their back and a v-shaped white area underneath.〔Nelson, 2002, S. 9〕 The plumage of one-year-olds can be almost completely brown. In the second year the birds’ appearance changes depending on the different phases of moulting: they can have adult plumage at the front and continue to be brown at the rear.〔 They gradually acquire more white in subsequent seasons until they reach maturity after five years. Newborn chicks are featherless and are dark blue or black in colour. In the second week of life they are covered in white down.〔 From the fifth week they are covered in dark brown feathers flecked with white.〔 Their beak is long, strong and conical with a slight downward curve at the end. The front part has a sharp edge. In adults, the beak is blue-grey with dark grey or black edges. It is brownish in immature birds. The northern gannet’s eyes are large and point forwards, and they have a light blue to light grey iris surrounded by a thin black ring. The four toes of their feet are joined by a membrane that can vary from dark grey to dark brown. There are yellow lines running along the toes that continue along their legs; these lines probably have a role in mating.〔 The rear toe is strong and faces inwards allowing the birds to firmly grip onto vertical cliff faces.〔 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「Northern gannet」の詳細全文を読む スポンサード リンク
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