UKBirds

Great Northern Diver

Gavia immer

The Great Northern Loon (Gavia immer), is a large member of the loon, or diver, family of birds. The species is known as the Common Loon in North America and the Great Northern Diver in Eurasia; its current name is a compromise proposed by the International Ornithological Committee.

Adults can range from 61 to 100 cm (24-40 inches) in length with a 122-152 cm (4-5-foot) wingspan, slightly smaller than the similar Yellow-billed Loon (or "White-billed Diver"). The weight can vary from 1.6 to 8 kg (3.6 to 17.6 lbs). On average a Great Northern Loon is about 81 cm (32 inches) long, has a wingspan of 136 cm (54 inches), and weighs about 4.1 kg (9 lbs).

Breeding adults have a black head, white underparts, and a checkered black-and-white mantle. Non-breeding plumage is brownish, with the chin and foreneck white. The bill is black-blue and held horizontally. The bill colour and angle distinguish this species from the similar Yellow-billed Loon.