Thick-billed Murre

Distribution, movements and phenology

The Thick-billed Murre breeds in coastal areas and on islands scattered throughout the Arctic (Billerman et al. 2026), remaining in these areas throughout the breeding season, between May and August. After this period, birds from some populations migrate to more southerly regions, utilising, for example, the waters of the North Atlantic, and may reach more temperate zones (Frederiksen et al. 2016). Based on data from six birds fitted with GLS between 2008 and 2012 and originating from colonies in Canada, Greenland and Iceland, the use of the Portuguese EEZ during the non-breeding period was observed. Records occurred in areas furthest from the coast, with particular emphasis on the Azores sub-area.

Abundance and population trends

The global population has been estimated at over 22,000,000 individuals, of which 1,920,000 to 2,840,000 mature individuals breed in Europe. Although the lack of up-to-date estimates, the population is believed to be increasing (BirdLife International 2025). In Portugal, this species is very rare, and there are no estimates of its abundance or population trend. There are only two records in the Azores accepted by the Portuguese Rarities Committee (Tipper et al. 2022).

Ecology and habitat

The Thick-billed Murre is a strictly marine species that feeds on fish, squid and crustaceans. It feeds both near the seabed, at relatively shallow depths, and in the water column (Billerman et al. 2026).

Threats and conservation

The species’ large global population suggests that, for the time being, there are no significant conservation concerns. However, some threats have been identified, namely egg harvesting, hunting of adult birds, disturbance of breeding colonies, pollution by oil and other toxic chemicals, bycatch in fishing gear and the degradation of its habitats (Billerman et al. 2026). It is also vulnerable to climate change, such as rising sea temperatures, which alter the availability of prey (Irons et al. 2008).