Species

Justification
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.

Taxonomic source(s)
AERC TAC. 2003. AERC TAC Checklist of bird taxa occurring in Western Palearctic region, 15th Draft. Available at: http://www.aerc.eu/DOCS/Bird_taxa_of _the_WP15.xls.
AOU. 1998. Check-list of North American birds. American Ornithologists' Union, Washington, D.C.
Cramp, S.; Perrins, C. M. 1977-1994. Handbook of the birds of Europe, the Middle East and Africa. The birds of the western Palearctic. Oxford University Press, Oxford.
Dowsett, R. J.; Forbes-Watson, A. D. 1993. Checklist of birds of the Afrotropical and Malagasy regions. Tauraco Press, Li
Sibley, C. G.; Monroe, B. L. 1990. Distribution and taxonomy of birds of the world. Yale University Press, New Haven, USA.
Stotz, D. F.; Fitzpatrick, J. W.; Parker, T. A.; Moskovits, D. K. 1996. Neotropical birds: ecology and conservation. University of Chicago Press, Chicago.

Distribution and population
The Common Guillemot has a circumpolar distribution, occuring in the low-arctic and boreal waters of the north Atlantic and north Pacific (del Hoyo et al. 1996).

Population justification
The global population is estimated to number > c.18,000,000 individuals (del Hoyo et al. 1996), while national population sizes have been estimated at < c.100 breeding pairs and c.50-10,000 wintering individuals in Japan and c.10,000-100,000 breeding pairs and c.1,000-10,000 individuals on migration in Russia (Brazil 2009).

Trend justification
The population trend is increasing in North America (based on BBS/CBC data: Butcher and Niven 2007).

Ecology
Behaviour The Common Guillemot is a pursuit-diving marine bird which forages primarily during daylight. One parent remains at the colony with the chick whilst the other is on a foraging trip. Birds departing colonies usually splash-down to form large rafts close to the colony before departing to foraging areas. External radio tagging has been shown to adversely effect breeding (Wanless et al. 1988, Nevins 2004), whereas birds fitted with internal transmitters behaved as normal (Wanless et al. 1988). Diet During the breeding season, schooling pelagic fish species are the most important prey for adults, though benthic species can also be important.In Labrador, Canada, Shannies (Sticheaidae) were the main source of food, comprising 84% of the diet in 1996 and 52.9% in 1997 (Bryant and Jones 1999). Capelin (Mallotus villosus) were also important, forming 44.7% of the diet in 1997 (Bryant and Jones 1999). In the UK, the main prey taxa are sandeel (Ammodytes spp.) and clupeids. Small gadoids are also important at some colonies. Foraging range This species dives to maximum depths of 170-230m. During the breeding season, surveys recorded the highest densities of birds in the 51 - 100 m depth zone, although birds were still abundant in water less than 50 m and 101 - 200 m deep. Very few were seen in deeper areas (Wanless et al. 1990). The foraging range of this species appears variable across seasons and years. At the Isle of May, Scotland, during 1986 around 70% of foraging trips were over 7 km from the colony, whereas in the following year the birds tended to make shorter trips (Wanless et al. 1990). Foraging trips in eastern Canada are within 100 km (Cairns et al. 1987, Davoren et al. 2003), and in Pribilof Islands, Alaska, foraging occurred mostly within 60 km. In Witless Bay, Newfoundland, foraging aggregations formed over large Capelin schools within 5 km of breeding sites. Along the Newfoundland coastline, aggregations occurred within 15 km of the colonies, and at an offshore ridge about 80 km southeast of the colonies. Despite these large foraging radii, waters close to the colony were the most frequent destination of feeding birds. This was particularly true during chick rearing, when only one third of feeding trips could have exceeded 10 km from the colony (Cairns et al. 1987). In Pribilof Islands, Alaska, birds showed a consistent preference for shallower waters (Schneider and Hunt 1984). High densities of foraging birds have also been observed foraging over a submarine ridge (Coyle et al. 1992). In Kachemak Bay, Alaska, it appears that birds tend to feed over rocky substrates in water depths of about 18 to 55 m (Sanger G.A. 1987). They have also been observed to forage in riptides (Wanless et al. 1990), and in areas of sandy sediment suitable for sandeels (Wanless et al. 1998, BirdLife International 2000). Near Flamborough Head, UK, the Farallones, California, and Pribilof Islands, Alaska, birds forage at fronts between thermally distinct bodies of water. In the UK example, this occurs at a seasonally-occuring front between thermally-mixed and thermally-stratified water, whereas in the Farallones, the front was between cold and salty upwellings and estuarine outflow (Decker and Hunt 1996, BirdLife International 2000).

Related state of the world's birds case studies

• Oil spills significantly reduce populations of seabirds and are costly to clean up
• Gillnets pose a significant threat to some seabird populations

References
del Hoyo, J.; Elliott, A.; Sargatal, J. 1996. Handbook of the Birds of the World, vol. 3: Hoatzin to Auks. Lynx Edicions, Barcelona, Spain.

BirdLife International. 2000. The Development of Boundary Selection Criteria for the Extension of Breeding Seabird Special Protection Areas into the Marine Environment. OSPAR Convention for the Protection of the Marine Environment of the North-East Atlantic. Vlissingen (Flushing).

Bryant, R.B. and Jones, I.L. 1999. Food resource use and diet overlap of common and thick-billed murres at the Gannet Islands, Labrador. Waterbirds 22(2): 392-400.

Cairns, D.K., Bredin, K.A. and Montevecchi, W.A. 1987. Activity budgets and foraging ranges of breeding common murres. Auk 104: 218-224.

Coyle, K.O., Hunt, G.L., Decker, M.B. and Weingartner, T.J. 1992. Murre foraging, epibenthic sound scattering and tidal advection over a shoal near St-George Island, Bering Sea. Marine Ecology Progress Series 83(1): 1-14.

Davoren, G.K., Montevecchi, W.A. and Anderson, J.T. 2003. The influence of fish behaviour on search strategies of common murres Uria aalge in the northwest Atlantic. Marine Ornithology 31(2): 123-131.

Decker, M.B. and Hunt, G. 1996. Foraging by murres (Uria spp.) at tidal fronts surrounding the Pribilof Islands, Alaska, USA. Marine Ecology Progress Series 139: 1-10.

Nevins, H.M. 2004. Diet, demography and diving behaviour of the common murre (Uria aalge) in central California. MSc Thesis.

Sanger G. A. 1987. Winter diets of Common Murres and Marbled Murrelets in Kachemak Bay, Alaska. Condor 891: 426-430.

Wanless S; Morris J. A; Harris M. P. 1988. Diving behavior of guillemot uria-aalge, puffin fratercula-arctica and razorbill alca-torda as shown by radio-telemetry. Journal of Zoology 216: 73-81.

Wanless, S., Harris, M.P. and Greenstreet, S.P.R. 1998. Summer sandeel consumption by seabirds breeding in the Firth of Forth, south-east Scotland. ICES Journal of Marine Science 55(6): 1141-1151.

Wanless, S., Harris, M.P. and Morris, J.A. 1990. A comparison of feeding areas used by individual common murres (Uria aalge) razorbills (Alca torda) and an Atlantic puffin (Fratercula arctica) during the breeding season. Colonial Waterbirds 13: 16-24.

Further web sources of information
Detailed species account from Birds in Europe: population estimates, trends and conservation status (BirdLife International 2004)

Hear sounds for this species from xeno-canto, the community database of shared bird sounds from around the world.

View photos and videos, and hear sounds of this species from the Internet Bird Collection

Text account compilers
Butchart, S., Calvert, R., Ekstrom, J., Hatchett, J.

IUCN Red List evaluators
Butchart, S., Symes, A.

Recommended citation
BirdLife International (2013) Species factsheet: Uria aalge. Downloaded from http://www.birdlife.org on 24/05/2013. Recommended citation for factsheets for more than one species: BirdLife International (2013) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 24/05/2013.

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.

Additional resources for this species

0