Thick-billed murres | Oceana Canada

Canadian Marine Life Encyclopedia

Thick-billed murres

Uria lomvia

Also known as

Brünnich’s Guillemont

Distribution

Circumpolar, Arctic and Subarctic

Ecosystem/Habitat

Nest on coastal cliffs; feed in the ocean

Feeding Habits

Active (diving) predator

Conservation Status

Not at Risk

Taxonomy

Order Charadriiforms (sandpipers, plovers, gulls, auks); Family Alcidae (auks)

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Thick-billed murres are a marine bird and the largest living member of the auk family. One of the most common Arctic bird species, these murres are deep-diving predators and regularly dive to depths of 100 metres in pursuit of prey such as fish, squid, crustaceans, polychaetes and molluscs. Incredibly, they are capable of diving deeper than 200 metres and staying submerged for more than three minutes! Thick-billed murres live in large groups called colonies, which sometimes can reach sizes of more than one million adult birds. They can be found in these dense aggregations during the breeding season on coastal cliffs. In Canada, populations of thick-billed murres can be found in British Columbia, Hudson’s Bay and all along the east coast.

Thick-billed murres are the largest living species of the auk family. In general, auks are known for their ability to “fly” better underwater than in the air. When underwater, they flap their wings to propel themselves through the ocean and use their feet as rudders to steer. The top of adult thick-billed murres are black along with their tail, head, legs, and feet, while their undersides are white or grey. Hatchlings are downy-grey or brown, with slightly lighter underside. Both sexes have the same colouration.

Thick-billed murres spend most of their lives at sea and only return to coastal cliffs to form large colonies to lay their eggs. They do not build nests, but rather lay and incubate their eggs directly on the rocks. They reach sexual maturity around three to five years of age and lay one egg per year. Both parents share the responsibility of incubating the egg for the 30 to 35-day nesting period. Babies leave the nest at about 15 to 30 days old. Accompanied by one of their parents, they jump from the cliff’s edge using their small wings to drift down to the waters below their nesting grounds. Dads will stay with and care for the chick for approximately eight weeks after they reach the water.

In the past, salmon drift-net fisheries were responsible for accidentally catching high numbers of thick-billed murres as bycatch. However, new regulations have substantially reduced these bycatch numbers. Thick-billed murres may also be seriously impacted by the overfishing of their main prey species. For example, the crash of capelin stocks in the Barents Sea in the 1980’s resulted in a decline in the thick-billed murre population in that region.

Thick-billed murres have not been assessed by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). They are listed as Least Concern by the IUCN due to their large and relatively stable population, and wide range. 

Climate change and warming oceans are likely to threaten thick-billed murre populations by changing the distribution of their prey species and rapidly altering Arctic environments. Studies have found that thick-billed murre populations begin to decline when there are temperature changes greater than 0.8 degrees Celsius. As sea ice melts, encroaching development in the Arctic may also impact these seabirds. Activities like unregulated hunting, oil pollution and increased shipping traffic in the fragile Arctic environment overlaps with important murre feeding grounds and may impact their foraging and breeding success.