Great Northern Diver

Gavia immer

70-90cm

Appearance

This bird is burly, and a fair bit larger than the Mallard. It has a big head with a steep forehead, a thick neck and a pointed bill. The sexes are similar, though colouring varies over the seasons. It is mostly black and white in summer; its back is chequered, its head is black though it can have a green sheen in the right light, and the neck is black with a white barred collar and two sets of white stripes. The bill is dark and the underparts are bright white. The winter plumage is dark grey and white; a dark cap descends below the eye, interrupted by a pale eye-ring. There's a hint of a dark half-collar at the base of the neck. In the first winter, these birds have brown backs and are edged with pale feathers. Juvenile birds are similar to the winter adult, though the upperparts are brownish-grey and the underparts are dirty-white.

Habitat

This bird doesn't have breeding areas in Britain or Ireland, but many Great Northerns visit coastal waters in the winter. It prefers rocky headland territories and can bear rough conditions; it can be found off Irish and Scottish coasts, and off the southwest of England.

Character

This bird is a powerful diver; it dives regularly for a minute or more. It has a habit of searching for food by sticking its head partly under water, and of rolling onto its side to preen its underparts. When it feels threatened, it will flee, swimming with only its head and neck above water. When flying, it is more sluggish looking than other divers, and its wingbeats are more shallow.

Food

Diet consists mostly of fish, particularly haddock, herring and sand eel. Also eats insects and their larvae, and crustaceans, including crabs and shellfish.

Breeding

Most females lay 2 eggs. Chicks often ride on the backs of their parents while they're small, and birds can breed after 2 years.

Population

Migrants begin arriving on the Scottish coast in August, followed by more birds during autumn; young birds sometimes migrate with their parents. Most birds depart Britain and Ireland by early May and return to their northern breeding grounds. This species is only known to have bred in Britain on one occasion. Approximately 2600 individuals spend winter in the UK, and 1400 in Scotland.

Observation Tips

The period between November and March is the best time to spot these birds off rocky shores around the coasts of Scotland and Ireland.

Voice

Usually silent, especially during the winter, but is does have a selection of yodelling songs that may be heard from breeding areas.
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