Thick-billed Murre

Identification

Since the extinction of the great auk in the mid-19th century, the murres are the largest living members of the Alcidae. The thick-billed murre and the closely related common guillemot (or common murre, U. aalge) are similarly sized, but the thick-billed still bests the other species in both average and maximum size. The thick-billed murre measures 40–48 cm (16–19 in) in total length, spans 64–81 cm (25–32 in) across the wings and weighs 736–1,481 g (26.0–52.2 oz). The Pacific race (U. l. arra) is larger than the Atlantic race, especially in bill dimensions.<p>Adult birds are black on the head, neck, back and wings with white underparts. The bill is long and pointed. They have a small rounded black tail. The lower face becomes white in winter. This species produces a variety of harsh cackling calls at the breeding colonies, but is silent at sea.<p>They differ from the common murre in their thicker, shorter bill with white gape stripe and their darker head and back; the "bridled" morph is unknown in U. lomvia – a murre has either a white eye-stripe, or a white bill-stripe, or neither, but never both; it may be that this is character displacement, enabling individual birds to recognize conspecifics at a distance in the densely packed breeding colonies as the bridled morph is most common by far in North Atlantic colonies where both species of guillemots breed. In winter, there is less white on the thick-billed murre's face. They look shorter than the common murre in flight. First year birds have smaller bills than adults and the white line on the bill is often obscure, making the bill an unreliable way to identify them at this age. The head pattern is the best way to distinguish first-year birds from common murres.

Taxonomy

Genus: Uria; Family: Alcidae; Order: Charadriiformes.

Scientific name

Uria lomvia

Authority

(Linnaeus, 1758)

Order

Charadriiformes

Family

Alcidae

Genus

Uria

Range and habitat

The thick-billed murre is distributed across the polar and sub-polar regions of the Northern Hemisphere where four subspecies exist; one lives on the Atlantic and Arctic oceans of North America (U. l. lomvia), another on the Pacific coast of North America (U. l. arra), and two others that inhabit the Russian arctic (U. l. eleonorae and U. heckeri). Thick-billed murres spend all of their lives at sea in waters which remain below 8°C, except during the breeding season where they form dense colonies on cliffs.

Breeding range

NA, PAL : HolArctic, high and low Arctic (locally temperate) coasts

Non-breeding range

s of pack-ice, to coastal New York

Migration

Complete migrants

Behavior

Migration pattern: Complete migrants.

Conservation

Population trend: rising.

Population trend

rising