Arctic loon (Gavia arctica)
|Also known as:||black-throated diver, black-throated loon|
|Size||Length: 62 - 75 cm (2)|
Wingspan: 100 - 130 cm (2)
|Weight||c. 2.6 kg (2)|
The Arctic loon is classified as Least Concern (LC) on the IUCN Red List (1).
The Arctic loon (Gavia arctica) is an elegant and distinctive diving bird, with a dark grey or black, dagger-shaped bill and deep red eyes (2) (3) (4). In the breeding adult, a conspicuous black and white striped pattern extends from the shoulders onto the lower neck (2) (5).
The upperparts of the Arctic loon are black and the underparts are white, although this white colouration is mostly hidden while swimming, except for two patches to the rear of the body (2) (3) (5). The back of the neck, head, throat and chin are matt grey (3). The front of the neck is black and sometimes has a green iridescence when the individual is in breeding plumage (2).
In winter, the upperparts of the Arctic loon become suffused with grey, the head and neck are darker, the black crown extends further down onto the eyes and the throat is white, without the striping seen in the summer plumage (2) (3) (4).
The juvenile Arctic loon has pale fringes to the feathers on the upperparts, giving it a scaled appearance, as well as a slightly browner plumage when compared with the adult (2) (3) (4).
Vocalisations of the Arctic loon include a barking ‘kwow’, as well as a shrill wail during the breeding season (5).
The large circumpolar range of the Arctic loon stretches from Alaska in the east to Siberia in the west. The breeding grounds of the Arctic loon are located in Russia, Scandinavia, Alaska and Canada (6) (7). During the winter months, the Arctic loon migrates south to the coasts of the northeast Atlantic and eastern and western Pacific (6), as far south as the Mediterranean, Black Sea, Caspian Sea, China, Japan and southern Alaska (7).
During the breeding season, the Arctic loon is found on large, inland, freshwater lakes, where it nests on small islands or around the edges of the water body (4) (5) (6). In winter, the Arctic loon migrates towards the sea, where it mainly inhabits sheltered coastlines, as well as inland lakes and lagoons (2) (6).
A highly migratory species, the Arctic loon forms flocks of up to 50 individuals and flies southwards after the breeding season to winter in warmer climates (6). Although it is a strong flier, the Arctic loon is almost incapable of walking on land due to the positioning of its legs. As a member of the family Gaviidae, this species is a skilled diver and is able to swim underwater (8) (9).
Fish, aquatic insects, molluscs and crustaceans are the main components of the Arctic loon’s diet, and frogs, leeches and plant matter are also occasionally taken (6) (9).
Courtship rituals such as bill-dipping, splashing and diving are performed by both the male and female Arctic loon at the beginning of the breeding season (9). The nest is built by both sexes and is usually made of a heap of plant matter, sometimes mixed with mud, with floating nests occasionally being made (6) (9). A single brood of between one and three olive-brown, speckled eggs is laid per year (9). The female incubates the eggs with help from the male, and when the eggs have hatched, both sexes feed the hatchlings, occasionally flying many miles to find food. The young Arctic loons begin to fly after 60 to 65 days (9).
The habitat of the Arctic loon is under threat due to acidification, water level fluctuations, oil spills and pollution, to which this species is highly vulnerable (6) (8). Human disturbances within the habitat, for example by tourists, also negatively affect the breeding success of the Arctic loon. In its coastal wintering grounds there is a large fishing industry, which also poses a threat to this bird as it is often caught as bycatch. Diseases such as avian influenza could also adversely affect population levels of the Arctic loon in the future (6).
In Scotland, artificial nesting areas have been created to improve breeding success of the Arctic loon in certain areas. In Sweden, nesting islands and the surrounding areas have been included in sanctuaries for this species (6). There are not known to be any other specific conservation measures currently in place for the Arctic loon.
Find out more about the Arctic loon:
BBC Wildlife Finder - Black-throated loon:
RSPB - Black-throated diver:
BirdLife International - Arctic loon:
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- Avian influenza: also known as “bird flu”, a contagious disease caused by any strain of influenza virus that is carried by and primarily affects birds.
- Bycatch: in the fishing industry, the part of the catch made up of non-target species.
- Crustaceans: diverse group of animals with jointed limbs and a hard external skeleton, characterised by the possession of two pairs of antennae, one pair of mandibles (mouthparts used for handling and processing food) and two pairs of maxillae (appendages used in eating, which are located behind the mandibles). Includes crabs, lobsters, shrimps, woodlice and barnacles.
- Incubation: the act of incubating eggs, that is, keeping them warm so that development is possible.
- Molluscs: a diverse group of invertebrates, mainly marine, that have one or all of the following: a horny, toothed ribbon in the mouth (the radula), a shell covering the upper surface of the body, and a mantle or mantle cavity with a type of gill. Includes snails, slugs, shellfish, octopuses and squid.
- Subspecies: a population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.
IUCN Red List (March, 2012)
- Brazil, M. (2009) Birds of East Asia. Christopher Helm, London.
- Dempsey, E. and O’Clery, M. (2002) The Complete Guide to Ireland’s Birds. Second Edition. Gill and Macmillan Ltd, Dublin.
- Barthel, P.H. and Dougalis, P. (2008) New Holland European Bird Guide. New Holland Publishers Ltd, London.
- Peterson, R.T., Mountfort, G. and Hollom, P.A.D. (1993) A Field Guide to the Birds of Britain and Europe. Houghton Mifflin Company, New York.
BirdLife International (March, 2012)
- Sibley, C.G. and Monroe, B.L. (1990) Distribution and Taxonomy of the Birds of the World. Yale University, Connecticut.
RSPB - Black-throated diver (March, 2012)
- Kaufman, K. (1996) Lives of North American Birds. Houghton Mifflin, New York.