The Australasian Gannet (Morus serratoris) is a large, mostly coastal seabird with predominantly white plumage, long, pointed wings, a long neck and slender body shape. The trailing edges of its wings and a varying proportion of its central tail feathers are black. The wedge-shaped bill is bluish-grey, with a lining of black; the skin surrounding the eye is intensely blue. The head plumage is buff-yellow, which extends down the neck. The sexes cannot be reliably distinguished in the field. Juveniles have mottled dark brown and white plumage, and are separable from the immatures, which gradually acquire more white over several molts, before acquiring full adult plumage at about 3 years old.

Ref: NZ BIRDS ONLINE

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