White-billed diver
The yellow-billed loon (Gavia adamsii ), also known as the white-billed diver, is the largest member of the loon or diver family. Breeding adults have a black head, white underparts and chequered black-and-white mantle. Non-breeding plumage is drabber with the chin and foreneck white. The main distinguishing feature from great northern loon is the longer straw-yellow bill which, because the culmen is straight, appears slightly uptilted.
It breeds in the Arctic and winters mainly at sea along the coasts of the northern Pacific Ocean and northwestern Norway; it also sometimes overwinters on large inland lakes. It occasionally strays well south of its normal wintering range, and has been recorded as a vagrant in more than 22 countries. This species, like all divers, is a specialist fish-eater, catching its prey underwater. Its call is an eerie wailing, lower pitched than the common loon.
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DiurnalDiurnal animals are active during the daytime, with a period of sleeping or other inactivity at night. The timing of activity by an animal depends ...
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CarnivoreA carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of a...
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PiscivoresA piscivore is a carnivorous animal that eats primarily fish. Piscivorous is equivalent to the Greek-derived word ichthyophagous. Fish were the die...
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NatatorialNatatorial animals are those adapted for swimming. Some fish use their pectoral fins as the primary means of locomotion, sometimes termed labriform...
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TerritorialA territory is a sociographical area that which an animal consistently defends against the conspecific competition (or, occasionally, against anima...
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TerrestrialTerrestrial animals are animals that live predominantly or entirely on land (e.g., cats, ants, snails), as compared with aquatic animals, which liv...
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CongregatoryCongregatory animals tend to gather in large numbers in specific areas as breeding colonies, for feeding, or for resting.
Oviparous animals are female animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive...
Precocial species are those in which the young are relatively mature and mobile from the moment of birth or hatching. Precocial species are normall...
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MonogamyMonogamy is a form of relationship in which both the male and the female has only one partner. This pair may cohabitate in an area or territory for...
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MigratingAnimal migration is the relatively long-distance movement of individual animals, usually on a seasonal basis. It is the most common form of migrati...
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starts withWith a length of 76 to 97 cm (30 to 38 in), a wingspan of 135 to 160 cm (53 to 63 in), and a weight ranging from 4 to 6.4 kg (8.8 to 14.1 lb), the yellow-billed loon is the largest member of the loon (diver) family. The adult is primarily black and white in breeding plumage, with a purple gloss on its head and neck.
The yellow-billed loon is an Arctic species, breeding primarily along the coasts of the Arctic Ocean as far north as 78° N and wintering on sheltered coastal waters of the northern Pacific Ocean and the northwestern coast of Norway. It has been recorded as a breeding bird in Russia, Canada and the United States. Though it winters primarily to the north of 50° N, its winter range extends south to 35° N off the coast of Japan, and it has been recorded as a vagrant in more than 20 countries, including some as far south as Mexico and Spain.
The yellow-billed loon is a specialist fish eater, yet it also takes crustaceans, molluscs and annelids, especially for its young. It dives in pursuit of prey, which is caught underwater. Probably as a way to avoid spreading parasites, it defecates ashore, in the breeding lake.
Like other loons, it forms long-lasting pairs. Though it prefers freshwater pools or lakes in the tundra, the yellow-billed loon will also breed along rivers, estuaries or the coast in low-lying areas of the Arctic; in general, it avoids forested areas. Breeding typically starts in early June, though it is dependent on the timing of the spring thaw. Like all members of its family, the yellow-billed loon builds a nest of plant material very close to the edge of the water. Copulation takes place on land, without any specific courtship. The pair defends its large territory intensively against intruders, but may later in the breeding season gang up with other birds on good fishing spots.
The female lays two eggs measuring 89 by 55 millimetres (3.5 by 2.2 in). The eggs are strongly oval, and are a light purple-brown with darker blotches interspersed. This colour camouflages with the soil and vegetation that this bird nests near. Most of the time, however, the egg is not visible due to incubation, which takes around 27 to 29 days.
In 2010, the IUCN (International Union for the Conservation of Nature) changed the status of the yellow-billed loon from Least Concern to Near Threatened, as the species appears to be in a "moderately rapid" population decline. An unsustainable level of subsistence harvesting by indigenous peoples was specifically named as the main threat.
The yellow-billed loon is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies; in the Americas, it is protected by the Migratory Bird Treaty Act of 1918.
