Yellow-billed Loon

With 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.

First described by English zoologist George Robert Gray in 1859 based on a specimen collected in Alaska, the yellow-billed loon is a monotypic species, with no subspecies despite its large Holarctic range. It is closely related to the common loon, which it strongly resembles in plumage and behaviour; some taxonomists consider the two species to be allopatric forms of the same superspecies. Both are thought to have evolved from a population of black-throated loons which colonized the Nearctic and were subsequently cut off from other populations. The genus name Gavia comes from the Latin for "sea mew", as used by ancient Roman naturalist Pliny the Elder. The specific epithet adamsii honours Edward Adams, a British naval surgeon and naturalist who sketched and collected numerous species, including this one, on several trips to the Arctic. The word "loon" is thought to have derived from the Swedish lom, the Old Norse or Icelandic lómr, or the Old Dutch loen, all of which mean "lame" or "clumsy", and is a probable reference to the difficulty that all loons have in moving about on land. "Diver" refers to the family's underwater method of hunting for prey, while "yellow-billed" and "white-billed" are references to the bird's distinctively pale bill.