The gannet commonly seen in New Zealand seas is the Australasian gannet, Sula bassana serrator, the antipodean race of the gannet of which two other races are in the North Atlantic and in South Africa. Our subspecies breeds both in this country and in south-eastern Australia, and has a range extending from Western Australia to the Chatham Islands and from the mid-Queensland coast to the seas south of Stewart Island. Gannets and their tropical relations, the boobies, are large seabirds with characteristically long, pointed wings and tail and powerful conical beaks. Their usual flight is an alternation of powerful wing-beats with an occasional glide. When fishing, whole flocks may suddenly plummet into the sea from a considerable height, with wings at first half open and then trailed close to the body just before the moment of impact. After a few moments the birds emerge, perhaps still holding a fish, and then, their food swallowed, they take off again to repeat the manoeuvre systematically. During the breeding season gannets come ashore and nest in colonies on islands or, in Hawke's Bay, on the mainland at Cape Kidnappers. Some 30 gannetries are known around the New Zealand coasts, a few supporting many thousands of nesting pairs. Here, these beautiful predominantly white birds with their golden crowns and black-tipped flight feathers can be seen to perfection indulging in ritualistic breeding displays. The main egg-laying period is October and November, and one white egg is laid in a hollow mound of vegetation, earth, and guano. Incubation takes 6½ weeks, and the young, born black and naked, soon become covered in white down. After about four months this has been replaced by mottled greyish-brown immature plumage and the young leave the gannetries and migrate to eastern Australia. From there they return to breed in their fourth year.
by Gordon Roy Williams, B.SC.(HONS.)(SYDNEY), Lecturer in Agricultural Zoology, Lincoln Agricultural College.