Yellow-billed Loon
Yellow-billed Loon ( Gavia adamsii )
The Yellow -billed Diver or Yellow -billed Loons ( Gavia adamsii ) is a species of bird in the genus of the loons (Gavia ). The species breeds in the coastal tundra of Russia and North America and winters in northern coasts. The Yellow -billed Diver may exceptionally be observed in Central Europe, especially in the winter on the coasts of North and Baltic Sea. The scientific species name honors the English naval surgeon and naturalist Edward Adams ( 1824-1856 ).
Description
The Yellow -billed Diver is the largest species of the genus Gavia. It reaches a body length of 77-90 cm and a wingspan of 135-150 cm. According to the few data available so far, the animals weigh 3.7 to 6.4 kg and are significantly heavier than a gray goose.
In breeding plumage the species is unmistakable. Ground color of the entire top and head and neck is black. The upper back is tight rows of large white squares, the rear back and the flanks show fine white dot rows. The neck has been located on the sides of a transverse oval field of white longitudinal lines on the throat a narrow line of white dots. Chest, abdomen and under wing-coverts are pure white.
The name derives from the large, pale yellow or ivory-colored and slightly raised beak, which usually extends slightly obliquely upwards while swimming through a corresponding head pose. The legs and feet are gray. The iris is burgundy.
In Plain dress the entire top is dark gray, but often still white speckled wings blankets are provided. Head and hind neck are dirty pale gray-brown, the dark color going forward on the throat and neck over white. To the eye, there is a fairly large white area. The beak is pale gray, darker at the base and there especially on the ridge. The forehead is raised sharply.
The juvenile plumage is very similar to the sizing dress, but the birds are yellow brown total oberseits more, the contour feathers of the top and the edges are also edged with light and thereby show a clean wave drawing. The beak is often not yet fully grown and pale gray to pale yellow.
Vocalizations
Flight calls are similar to those of other loons those of geese. The mating calls are far-reaching yodeling or howling.
Distribution and habitat
The range of the species includes the coastal tundra of Russia and North America. The Russian area ranges from the Murman coast east to Chukotka. In North America, the species is found in the central northern Canada as well as on the north coast of Alaska. During the breeding season the species inhabits inland waters in the lowlands.
Nutrition
The food is hunted diving and consists mainly of fish, in addition to frogs, crustaceans, molluscs and looted.
Reproduction
Many aspects of reproduction are hardly known. The nests are built on the banks of the waters and usually consist of a bottom tray, which is sometimes also designed with plant parts. Eggs are laid in mid-June to mid-July. The nest consists normally of two eggs. The incubation period lasts at least 27 days; the eggs are incubated by both parents and the chicks then jointly.
Hiking
Yellow -billed Diver are apparently predominantly medium-to short-distance migrant. The deduction from the breeding area is unknown, first over the winter, however, observed in October. The Russian birds wintering on the one hand, on the northern Pacific coast of Asia, on the other off the coast of Norway, but apparently also regularly in the northern Baltic Sea. The populations of North America spend the winter before the American Pacific coast from southern Alaska to the central California. The return to the breeding grounds takes place from mid-May. The species is rarely detected until April of October in Central Europe, especially on the coasts of North and Baltic Seas, and only exceptionally inland on larger lakes.
Inventory and risk
The IUCN classifies the Yellow -billed Diver since 2010 as a small extent jeopardizes. Both in much of the breeding and wintering area of the oil is produced. Oil spills can therefore have negative inventory effects. This is especially true for the population in Alaska, where 90 percent of the stock breeds in a region that is provided for the removal of oil and gas reserves.
The Yellow -billed Diver is also partially hunted by the indigenous population in its area of distribution. There are different estimates of how this hunt is a threat to this type