Great northern diver
Encyclopedia : G : GR : GRE : Great northern diver
The Great Northern Diver, known in North America as the Common Loon (Gavia immer), is a large member of the loon, or diver, family. Adults are typically 73–88 cm (28–36 in) in length with a 122–148 cm wingspan, slightly smaller than the similar White-billed Diver. They weigh between 2.7 and 6.3 kg with a mean value around 4.1 kg.
The Great Northern Diver breeds in Canada, parts of the northern United States, Greenland, and Alaska. There is a smaller population (ca. 3000 pairs) in Iceland. The female lays 2 eggs on a mound of vegetation very close to water. Both parents build the nest and feed the young.
This species winters on sea coasts or on large lakes over a much wider range in Northern Europe and the British Isles as well as in North America.
Breeding adults have a black head, white underparts, and a chequered black-and-white mantle. Non-breeding plumage is drabber, with the chin and foreneck white. The bill is grey or whitish and held horizontally. The bill colour and angle distinguish this species from the similar White-billed Diver.
This species, like all divers, is a specialist fish-eater, catching its prey underwater, diving as deep as 200 feet (60 m). Freshwater diets consist of pike, perch, sunfish, trout and bass; salt water diets consist of rock cod, flounders, sea trout and herring. It flies with its neck outstretched.
The tremolo call, sometimes referred to as "loon laughter", is an eerie wailing, a symbol of the Canadian wilderness, and often used as atmosphere in horror films. Native tribes of British Columbia believed that an excess of calls from this bird predicted rain, and even brought it.
This diver is well-known in Canada, appearing on the "loonie" coin and $20 bill, and is the provincial bird of Ontario. Also, it is the state bird of Minnesota.
Folk names include big loon, black-billed loon, call-up-a-storm, ember-goose, greenhead, guinea duck, imber diver, ring-necked loon, and walloon.
These birds have disappeared from some lakes in eastern North America due to the effects of acid rain and pollution. Artificial floating nesting platforms have been provided for loons in some lakes to reduce the impact of changing water levels due to dams and other human activities.
Gavia is Latin for "sea smew" (although divers are not Smew). The specific meaning of immer either is:
- related to Swedish immer and emmer, the gray or blackened ashes of a fire, referring to its dark plumage; or
- Latin immergo, to immerse, and immersus, submerged.
Morphology of the skull
References
- BirdLife International (2004). [Gavia immer]. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 09 May 2006. Database entry includes justification for why this species is of least concern
External links
- [Loons]
- [Great Northern Diver videos] on the Internet Bird Collection
From Wikipedia, the Free Encyclopedia. Original article here. Support Wikipedia by contributing or donating.
All text is available under the terms of the GNU Free Documentation License See Wikipedia Copyrights for details.