Cold comfort: Arctic seabirds find refugia from climate change and potential competition in marginal ice zones and fjords

Climate change alters species distributions by shifting their fundamental niche in space through time. Such effects may be exacerbated by increased inter-specific competition if climate alters species dominance where competitor ranges overlap. This study used census data, telemetry and stable isotopes to examine the population and foraging ecology of a pair of Arctic and temperate congeners across an extensive zone of sympatry in Iceland, where sea temperatures varied substantially. The abundance of Arctic Brünnich’s guillemot Uria lomvia declined with sea temperature. Accessibility of refugia in cold water currents or fjords helped support higher numbers and reduce rates of population decline. Competition with temperate Common guillemots Uria aalge did not affect abundance, but similarities in foraging ecology were sufficient to cause competition when resources are limiting. Continued warming is likely to lead to further declines of Brünnich’s guillemot, with implications for conservation status and ecosystem services.

Biometrics as a determinant of the origins of seabirds killed in oil spills and other incidents

Common Guillemots Uria aalge and Brünnich's Guillemots U. lomvia are common victims of oil spills, drowning in fishing nets and winter wrecks. Because the Norwegian population of Common Guillemots is classified as critically endangered and the Russian population of the Brünnich's Guillemot has declined greatly, it is important to be able to identify the origins of birds killed outside the breeding season. Measurements of birds made in nine colonies in the Barents and Norwegian Seas showed that although it is impossible to determine with reasonable accuracy the colony of origin from body measurements, the most likely sea of origin of Common Guillemots may be determined on the basis of wing and head + bill lengths, whereas there was no systematic variation in any measurement of Brünnich's Guillemots.

The significance of Southwest Greenland as winter quarters for seabirds

The coastal and offshore waters of Southwest Greenland are internationally important winter quarters for seabirds. We crudely estimate a minimum of 3.5 million seabirds using the region in winter, mainly from Arctic Canada, Greenland and Svalbard, with smaller numbers also from Alaska, Iceland, mainland Norway and Russia. The most numerous species are Common Eider Somateria mollissima, King Eider S. spectabilis, Brünnich's Guillemot Uria lomvia and Little Auk Alle alle. The most immediate threat to the seabirds in Southwest Greenland is hunting, and current levels of usage of the Greenland breeding populations of Brünnich's Guillemot and Common Eider are considered unsustainable. Conservation measures are required for these populations.