Black-throated Loon, Gavia arctica

The Black-throated Loon (Gavia arctica) is an aquatic bird found in the northern hemisphere. In North America this species is known as the Arctic Loon. In Eurasia it is known as the Black-throated Diver. Its current name is a concession of both other names, proposed by the International Ornithological Committee.

The Black-throated Loon is one of a many species that was originally described by Linnaeus in his eighteenth century work, Systema Naturae. The genus name, Gavia, comes from the Latin for “sea mew,” as used by ancient Roman naturalist Pliny the Elder.

It is found mainly in Eurasia during breeding seasons, with some occurrence in western Alaska. It winters at sea, and often on large lakes over a wider range. This species is also a vagrant to Pakistan.

The breeding adult is 25 to 30 inches long with a 40 to 48-inch wingspan. It is shaped like a smaller, sleeker version of the Great Northern Diver. It has a gray head, black throat, white underparts and checkered black-and-white mantle. The non-breeding adult is duller in appearance with the chin and foreneck white. It has a grayish, dagger-shaped bill. The flank patch is white in all plumages, which distinguishes it from all other divers including the identical Pacific Diver.

The Black-throated Loon is a fish-eating diving bird. It specializes in catching its prey underwater. It flies with an outstretched neck. It also feeds on insects, crustaceans and amphibians. Its calls include a yodeling, high-pitched wail and harsh growls, similar but lower pitched than Pacific Loon.

This is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies. The species has decreased in population through much of its habitat. However, there was as much as a 34 percent increase in the population of the Black-throated Diver in the UK over the past 12 years.

Dr Mark Eaton, an RSPB Scotland scientist, traced the drop in overall numbers to warming of the North Sea which reduced stocks of the fish on which they feed.

The Black-throated Diver is the current school emblem of Achfary Primary School.

Image Credit: Carley, Curtis/Wikipedia (public domain)