Great Northern Loon

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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 .| [2]

Taxonomy

The Great Northern Loon is one of the fiveloonspecies that make up the genus Gavia, the only genus of the family Gavidae and order Gaviiformes. Its closest relative is the other large black-headed species, theYellow-billed Loonor White-billed Diver, Gavia adamsii.|[3]

The genus name Gavia was theLatinterm for theSmew(Mergellus albellus). This small sea-duck is quite unrelated to loons and just happens to be another black-and-white seabird which swims and dives for fish. It is not likely that theAncient Romanshad much knowledge of loons, as these are limited to more northernlatitudesand since the end of thelast glacial periodseem to have occurred only as rare winter migrants in theMediterraneanregion.[4][5]The specific name immer is derived from North Germanic names for the bird such as modern Icelandic "Himbrimi".[6]The term is related to Swedish immer and emmer, the grey or blackened ashes of a fire, referring to its dark plumage; or to Latin immergo, to immerse, and immersus, submerged.[7]

The European name "diver" comes from the bird's habit of catching fish by swimming calmly along the surface and then abruptly plunging into the water. The North American name "loon" is a reference to the bird's clumsiness on land, and is derived from Scandinavian words for lame, such as Icelandic "lúinn" and Swedish "lam".[6]

[edit]Description
undefinedundefinedSwimming onGull Lake, Ontario, CanadaAdults 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 similarYellow-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).

Breedingundefinedadultshave a black head, white underparts, and a checkered black-and-white mantle. Non-breedingplumageis 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.

[edit]Distribution and habitat
The Great Northern Loon breeds inCanada, parts of the northernUnited States,Greenland, andAlaska. There is a smaller population (ca. 3,000 pairs) inIceland. On isolated occasions they have bred in the far north ofScotland. The female lays 1 to 3eggson a hollowed-out mound of dirt and vegetation very close towater. Bothparentsbuild thenest, sit on the egg or eggs, and feed the young.

Thisspecieswinters onseaundefinedcoastsor on largelakesover a much wider range inEuropeand theBritish Islesas well as inNorth America.

Behaviour Chicks will ride on their parents' backsundefinedundefinedFlying in Vermont, USAThisspecies, like all divers, is a specialistfish-eater, catching its prey underwater, diving as deep as 200 feet (60 m). Freshwater diets consist ofpike,perch,sunfish,trout, andbass; salt-water diets consist ofrock fish,flounder,sea trout, andherring.

The bird needs a long distance to gain momentum for take-off, and is ungainly on landing. Its clumsiness on land is due to the legs being positioned at the rear of the body: this is ideal for diving but not well-suited for walking. When the birds land on water, they skim along on their bellies to slow down, rather than on their feet, as these are set too far back. The loon swims gracefully on the surface, dives as well as any flying bird, and flies competently for hundreds of kilometers in migration. It flies with its neck outstretched, usually calling a particular tremolo that can be used to identify a flying loon. Its call has been alternately called "haunting," "beautiful," "thrilling," "mystical" and "enchanting."[8][9]

Great Northern Loon nests are usually placed on islands, where ground-based predators cannot normally access them. However, eggs and nestlings have been taken bygulls,corvids,raccoons,skunks,minks,foxes,snapping turtlesand largefish. Adults are not regularly preyed upon, but have been taken bysea otters(when wintering) andbald eagles.[10]undefinedOspreyshave been observed harassing divers, more likely out ofkleptoparasitismthan predation.[11]When approached by a predator of either its nest or itself, divers sometimes attack the predator by rushing at it and attempting to impale it through the abdomen or the back of the head or neck.

[edit]Relationship with humans
undefinedundefinedNest near to water inMaine, United StatesThese birds have disappeared from some lakes in easternNorth Americadue to the effects ofacid rainandpollution, as well as lead poisoning from fishing sinkers and mercury contamination from industrial waste. Artificial floating nesting platforms have been provided for loons in somelakesto reduce the impact of changing water levels due todamsand other human activities.

The Great Northern Loon is one of thespeciesto which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies.

This diver is well known inCanada, appearing on the"loonie"undefinedcoinand the previous series of$20 bill, and is theprovincial birdofOntario. Also, it is thestate birdofMinnesota.

The voice and appearance of the Great Northern Loon has made it prominent in severalNative Americantales. These include a story of a loon which created the world in aChippewastory; aMicmacsaga describes Kwee-moo, the loon who was a special messenger of Glooscap (Glu-skap), the tribal hero; native tribes ofBritish Columbiabelieved that an excess of calls from thisbirdpredictedrain, and even brought it; and the tale of the loon's necklace was handed down in many versions among Pacific Coast peoples. Folk names include big loon, black-billed loon, call-up-a-storm, ember-goose, greenhead, guinea duck, imber diver, ring-necked loon, and walloon.

This bird is central to the plot of the novel Great Northern? byArthur Ransome(in which it is referred to throughout as Great Northern Diver, with the obsolete scientific name Colymbus immer). The story is set in theOuter Hebrides, where the main characters—a group of children on holiday—notice a pair of loons apparently nesting there. Checking their bird book, they believe this to be the Great Northern Loon; however, this has not previously been seen to nest in northern Scotland, and so they ask for help from an ornithologist. He confirms that these birds are indeed the Great Northern; unfortunately, it soon transpires that he does not wish merely to observe, but wants to steal the eggs and add them to his collection; and to do this, he must first kill the birds. Published in 1947, the story is one where the conservationists are the eventual victors over theegg collector, at a time when the latter hobby was not considered to be harmful.[12][13]