Arctic Loon

The adult black-throated loon is 58 to 73 cm (23 to 29 in) in length with a 100 to 130 cm (39 to 51 in) wingspan and a weight of 1.3 to 3.4 kilograms (2.9 to 7.5 lb). The nominate subspecies in its breeding plumage has a grey head and hindneck, with a black throat and a large black patch on the foreneck, both of which have a soft purple gloss. The lower throat has a necklace-shaped patch of short parallel white lines. The sides of the throat have about five long parallel white lines that start at the side of the patch on the lower throat and run down to the chest, which also has a pattern of parallel white and black lines. The rest of the underparts, including the centre of the chest, is pure white. The upperparts are blackish down to the base of the wing, where there are a few rows of high contrast white squares that cover the mantle and scapulars. There are small white spots on both the lesser and median coverts. The rest of the upperwing is a blackish colour. The underwing is paler than the upperwing, and the underwing coverts are white. The tail is blackish. The bill and legs are black, with a pale grey colour on the inner half of the legs. The toes and the webs are grey, the latter also being flesh coloured. The irides are a deep brown-red. …

The black-throated loon has a large range, breeding taking place across northern Europe, Asia, and the Seward Peninsula in Alaska. When breeding, it is found in the area around isolated, deep freshwater lakes larger than 0.1 square kilometres (0.039 mi2), especially those with inlets, as it prefers to face only small stretches of open water. When it is not breeding, this loon moves in a general southward direction and towards ice-free sea, usually wintering on the coasts of the north-east Atlantic Ocean and those on the eastern and western Pacific Ocean, such as the coasts of Japan. During this time, its habitat is usually inshore waters along sheltered coasts, although it will sometimes be found inland, in places such as the Mediterranean and Black seas.

Like other loons, this bird does not take flight well; it takes off by pattering on a "runway" of water. While flying, it makes a barking "kwow" flight call.

Breeding. This species usually nests on the ground within about 1 metre (3.3 ft) of the lake it breeds at. This loon also sometimes nests on vegetation, like Arctophila fulva, that has emerged from lakes. The nest site is often reused the next year. The nest itself is oval-shaped and built mostly by the female out of heaped plant material like leaves and sticks. The nest is about 23 centimetres (9.1 in) across. Families of black-throated loons often move their nest site from the original nest ponds they inhabited to wetlands nearby after the chicks reach two weeks of age. The journey is generally less than 150 metres (490 ft). In the southern portion of its range, this loon starts to breed in April, whereas in the northern parts of its range, it waits until the spring thaw, when there is adequate water for it to take off. It usually arrives before the lake thaws, in the latter case. Before copulation, the female hunches its neck and swims close to the shore until it finds a suitable place and then lies down on the shore. The male sometimes adopts the same posture as the female. During this time, the only vocalization made is a one note "hum". …

The black-throated loon was formally described in 1758 by the Swedish naturalist Carl Linnaeus in the tenth edition of his Systema Naturae under the binomial name Colymbus arcticus. Linnaeus specified the type locality as Europe and America but in 1761 he restricted it to Sweden. In 1897 the American ornithologist Joel Asaph Allen suggested that the black-throated loon should be moved to the genus Gavia that had been introduced by Johann Forster in 1788. This proposal was adopted by the American Ornithologists' Union (AOU) in 1899. The genus name Gavia comes from the Latin for 'sea mew', as used by the ancient Roman naturalist Pliny the Elder. The specific arctica is Latin for 'northern' or 'Arctic'. The name of the subspecies viridigularis stems from the Latin viridis, meaning 'green', and the Latin gularis, meaning 'throated', in reference to the green throat of this subspecies. The common name, black-throated loon, stems from its black throat patch. This loon is also called the Arctic loon and the black-throated diver. There are two subspecies:

Gavia arctica arctica (Linnaeus, 1758) – This subspecies is found in northern Europe, east to the center of northern Asia, and from that to the Lena River and Transbaikal. It migrates to the coasts of northwestern Europe and the coasts of the Mediterranean, Black, and Caspian Seas. G. a. …