Arctic Loon Identification Guide

Key Field Marks

• Medium-sized loon, intermediate between Pacific Loon and Common Loon in bulk, with a fairly straight, medium-length bill often held level or slightly uptilted.
• Breeding adult: pale gray crown and nape, black throat glossed with purple and green, and a checkerboard pattern of black-and-white squares on the back.
• The most reliable mark on swimming birds: a bold white patch on the flank/side, visible as a white flash above the waterline near the rear of the body — this patch is the key difference from the very similar Pacific Loon.
• Non-breeding (winter) birds are dark gray-brown above and white below, with a fairly sharp, clean line dividing the dark hindneck from the white foreneck.
• Neck appears slightly thicker and the head shape blockier than Pacific Loon.

Separating from Similar Species

• Pacific Loon: extremely similar and the main identification challenge; Pacific Loon lacks the white flank patch (or shows at most a thin sliver), typically shows a more contrasting dark chinstrap in breeding plumage, and has a thinner, more delicate bill and rounder head. Pacific Loon is also much more numerous in North America.
• Common Loon: notably larger and bulkier with a thicker, dagger-like bill, more extensively white-spotted (not neatly checkered) back, and lacks the clean gray hood of Arctic/Pacific Loon.
• Confirming the white flank patch on a swimming bird is the single best way to separate Arctic from Pacific Loon in the field.

Habitat & Range

• Breeds on freshwater tundra and taiga lakes across northern Eurasia, with a small breeding presence in western Alaska where its range approaches that of the much commoner Pacific Loon.
• Winters along temperate coastlines, mainly in Europe and Asia, on sheltered bays and nearshore marine waters.
• In North America it is a rare bird, chiefly recorded in western Alaska and as a vagrant elsewhere along the Pacific coast.

Voice

• Similar to other loons: wailing and yodeling calls on the breeding grounds, plus low croaking notes; largely silent in winter away from breeding territories.