Thick-billed Murre Uria lomvia


Justification of Red List Category
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be increasing, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is extremely large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.

Population justification
The global population is estimated to number >22,000,000 individuals (del Hoyo et al. 1996). The European population is estimated at 1,920,000-2,840,000 mature individuals (BirdLife International 2015). The population in Russia has been estimated at c.10,000-1 million breeding pairs (Brazil 2009).

Trend justification
In North America, the population is increasing (based on BBS/CBC data: Butcher and Niven 2007). The European population trend is unknown (BirdLife International 2015).

Distribution and population

This species has a circumpolar distribution in the arctic and high arctic regions of North America, Europe and Asia breeding on coasts and islands. It breeds as far south as the Kuril Islands (Russia), Newfoundland and Labrador (Canada) and Alaska (U.S.A.), and also winters off the coast of central Japan (del Hoyo et al. 1996).


This species is exclusively marine, ranging along sea coasts and as far offshore as the continental shelf edge. It feeds chiefly on fish, squid and crustaceans throughout the year, supplemented by polychaetes and molluscs. Fish predominate during summer, with the main species varying with locality, and are usually caught close to the colony. Birds arrive at colonies in the spring, though the start of laying is variable depending on sea temperature, laying latest where the temperatures are lowest (e.g. early July in the high Arctic). It is a highly colonial species, usually forming immense aggregations on sea cliffs and narrow ledges. The extent and timing of post-breeding dispersal is largely determined by ice conditions and food availability. During the winter periods, the species can be found in large flocks at sea, likely related to the non-random distribution of winter prey (del Hoyo et al. 1996).


The Thick-billed Murre is vulnerable to changes in climate, with populations declining in response to sea surface temperature changes in excess of 0.8˚C, but increasing at moderate temperature increases (0.3-0.8˚C) (Irons et al. 2008). This is likely due to changes in prey availability and, as such, is aggravated by the loss of upper trophic level fish and whales due to food-web disruption (Irons et al. 2008). Hunting is unregulated in Greenland, Newfoundland and Labrador and is considered to have resulted in population declines, as shown for Greenland (Merkel et al. 2016). Mortality from bycatch has been widely reported throughout the range, especially in the salmon drift-net fishery, previously responsible for a very high rate of bycatch, although this has decreased in recent years with the introduction of new regulations and reduction of fishing effort (Gaston and Hipfner 2000).

Conservation actions

Conservation Actions Underway
There are no known current conservation measures for this species within its European range.

Conservation Actions Proposed
The following information refers to the species's European range only: There are a number of immediate conservation requirements for this species. Enhanced monitoring of major colonies is needed, particularly in Iceland, Spitsbergen and the Russian Arctic, where population size and status are inadequately known. Detailed assessment of impacts of overfishing by commercial fisheries is required, particularly of capelin, cod, herring and sand eels in the Barents Sea and Iceland. Continue and expand assessments of by-catch in gill-net fisheries, particularly in the north-east Atlantic. Tighter legislation and penalties (national and international) associated with oil pollution from offshore developments and transport should be developed. The eradication of alien predators, especially foxes at Russian colonies should be undertaken (Nettleship and Christie 2013).


Text account compilers
Ekstrom, J., Ashpole, J, Fjagesund, T., Calvert, R., Martin, R., Stuart, A., Butchart, S.

Recommended citation
BirdLife International (2022) Species factsheet: Uria lomvia. Downloaded from on 17/08/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from on 17/08/2022.