• Summary
• Text account
• Data table and detailed info
• Distribution map
• Reference and further resources

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 stable, 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 very 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 c.400,000-1,500,000 individuals (Wetlands International 2015). The European population is estimated at 46,500-135,000 pairs, which equates to 93,000-270,000 mature individuals (BirdLife International 2015).

Trend justification
The overall population trend is stable (Wetlands International 2015). This species has undergone a small or statistically insignificant increase over the last 40 years in North America (data from Breeding Bird Survey and/or Christmas Bird Count: Butcher and Niven 2007). Note, however, that these surveys cover less than 50% of the species's range in North America. The European population trend is estimated to be stable (BirdLife International 2015).

This species breeds in the Arctic regions of the northern hemisphere. Birds breeding in northern Europe and Asia tend to remain near the colony year-round. Breeders in North America migrate south, being found in the North Pacific from California (U.S.A.) round to the extreme south-east of Russia, off the western coast of North America down to Virginia, and the Atlantic coast of Europe down to Brittany, France including the United Kingdom and Ireland (del Hoyo et al. 1996).

Behaviour Most populations of this species migrate southwards after breeding although some western Palearctic breeders remain on their breeding grounds throughout the year (del Hoyo et al. 1996). The species breeds from mid-May to mid-June (the timing depending on latitude and ice conditions) in solitary pairs or small colonies (del Hoyo et al. 1996), departing the breeding grounds from September to mid-October (Olsen and Larsson 2003). Outside of the breeding season the species is gregarious and occurs in small or large flocks, up to tens of thousands gathering where food is temporarily abundant (Snow and Perrins 1998) during the winter (e.g. at fishing harbours) (Olsen and Larsson 2003). Habitat It breeds on sea cliffs and inshore islands (del Hoyo et al. 1996, Snow and Perrins 1998), particularly near human settlements and often near colonies of other gulls or geese (del Hoyo et al. 1996). The species may also breed on islands in lakes near the coast (del Hoyo et al. 1996, Snow and Perrins 1998) or on the edges of coastal lagoons (Snow and Perrins 1998). Throughout the year the species forages over coasts, bays, harbours, inshore waters with sewage outfalls, the intertidal zone, land-fill sites, fishing wharves and large inland lakes (del Hoyo et al. 1996). Diet Its diet consists of fish, molluscs, Echinoderms, crustaceans, rodents, adult and young birds, eggs (especially of ducks, auks and shorebirds), insects, berries and carrion (del Hoyo et al. 1996). Breeding site The nest is a mound of seaweed and debris (del Hoyo et al. 1996), usually placed on the edges of cliffs, rock pinnacles (del Hoyo et al. 1996), rocky outcrops (Snow and Perrins 1998), slopes (del Hoyo et al. 1996) and occasionally on ice or snow (Snow and Perrins 1998).

The species is threatened by organohalogen pollution in its Arctic breeding range (Bustnes et al. 2004, Verreault et al. 2007), with evidence that organohalogen contaminants alter the species's basal metabolic rate (Verreault et al. 2007) and that organochlorines reduce the efficiency of its immune system (Bustnes et al. 2004). However, this is not considered to pose a significant threat to the species.

Conservation Actions Underway
The following information refers to the species's European range only: The species is covered under the African Eurasian Waterbird Agreement. There are 16 Important Bird Areas which include this species in Europe. Within the EU there are three Special Protection Areas which include this species. 

Conservation Actions Proposed
The following information refers to the species's European range only: Monitor contaminant build-up within individuals; identify important sites (breeding and at sea) and designation these as protected areas.

Text account compilers
Ashpole, J, Butchart, S., Calvert, R., Bennett, S., Ekstrom, J., Malpas, L., Martin, R., Stuart, A.

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Recommended citation
BirdLife International (2024) Species factsheet: Glaucous Gull Larus hyperboreus. Downloaded from https://datazone.birdlife.org/species/factsheet/glaucous-gull-larus-hyperboreus on 22/12/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from https://datazone.birdlife.org/species/search on 22/12/2024.