Common Loon

The common loon or great northern diver (Gavia immer) is a large member of the loon, or diver, family of birds. Breeding adults have a plumage that includes a broad black head and neck with a greenish, purplish, or bluish sheen, blackish or blackish-grey upperparts, and pure white underparts except some black on the undertail coverts and vent. Non-breeding adults are brownish with a dark neck and head marked with dark grey-brown. Their upperparts are dark brownish-grey with an unclear pattern of squares on the shoulders, and the underparts, lower face, chin, and throat are whitish. The sexes look alike, though males are significantly heavier than females. During the breeding season, loons live on lakes and other waterways in Canada, the northern United States (including Alaska), and southern parts of Greenland and Iceland. Small numbers breed on Svalbard and sporadically elsewhere in Arctic Eurasia. Common loons winter on both coasts of North America as far north as Newfoundland and Alaska, and as far south as Mexico, as well as on the Atlantic coast of Europe.

Abridged excerpt from the Wikipedia article Common loon, by its authors, under the CC BY-SA 4.0 licence.