Thick-billed Murre

The Thick-billed Murre replaces the Common Murre at higher latitudes, breeding farther north into the Arctic and tolerating colder, ice-influenced waters. Its blacker plumage and heavier bill with a distinctive pale stripe help separate it from its close relative where the two overlap.

• Upperpart feathers are a deeper, blacker tone than the browner Common Murre, giving a crisper, higher-contrast appearance against the white underparts
• The border between dark upperparts and white underparts is generally sharper and more clean-cut than in Common Murre
• A pale whitish stripe along the base of the bill (visible on the bird, not the feather) accompanies the thicker bill shape that gives the species its name
• Flight feathers are narrow and pointed, supporting fast, whirring flight typical of murres
• Tail feathers are short and squared, in keeping with the compact, elongated auk body plan

• Breeding adults show blackish head, neck, and upperparts against clean white underparts, with a sharper contrast than Common Murre
• Non-breeding adults show white extending onto the lower face, though generally less extensively than in Common Murre
• Juveniles resemble adults but with softer feather edges and less crisp contrast
• Sexes are alike in plumage
• A complete molt after breeding, including flight feathers, results in a flightless period spent on the water

Thick-billed Murres breed on steep sea cliffs in high-Arctic and subarctic regions around the North Atlantic and North Pacific, often nesting alongside Common Murres where ranges overlap. Outside the breeding season they winter over cold continental shelf waters and near pack ice edges, generally remaining farther north than Common Murre in winter.

This murre dives to considerable depths in pursuit of fish and invertebrates, using its wings for underwater propulsion much like other auks. It lays a single pointed egg on a bare cliff ledge, with chicks leaving the ledge for the sea well before they can fly, accompanied by a parent. Its call is a low, growling note similar to that of the Common Murre, given mainly at dense breeding colonies.