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Black Guillemot Cepphus grylle

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 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.

Taxonomic source(s)
AERC TAC. 2003. AERC TAC Checklist of bird taxa occurring in Western Palearctic region, 15th Draft. Available at: _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.
Sibley, C. G.; Monroe, B. L. 1990. Distribution and taxonomy of birds of the world. Yale University Press, New Haven, USA.

Distribution and population
The Black Guillemot can be found throughout Arctic waters on the northern coasts of Russia, Alaska (USA), Canada and Norway, in the Atlantic Ocean off Greenland (to Denmark), eastern Canada as far south as the United Kingdom including the North and Baltic Sea (del Hoyo et al. 1996).

Population justification
The global population is estimated to number c.400,000-700,000 individuals (del Hoyo et al. 1996), while the population in Russia has been estimated at < c.100 breeding pairs and < c.50 individuals on migration (Brazil 2009).

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

Behaviour Black Guillemots are pursuit divers that propel themselves through the water using their wings. Diet The species is probably primarily a benthic forager, since much of the prey consists of benthic fish and invertebrates, including crustaceans (Bradstreet and Brown 1985, Cairns 1987a, BirdLife International 2000). Various studies find sandeels (Ammodytes spp.) (Harris and Riddiford 1989, Ewins 1990) and blennies (particularly butterfish Pholis gunnellus) (Harris and Riddiford 1989, Ewins 1990, BirdLife International 2000) to be the most important prey species of fish, although the relative contributions of each of these to the overall diet differs. Flatfish (Harris and Riddiford 1989) and gadoids (Ewins 1990) are also sometimes important. Amongst invertebrates, sea-scorpions are noted as an important prey item (Harris and Riddiford 1989). Adults tend to consume a higher proportion of invertebrates than chicks (Ewins 1990). The general trend is for increasing importance of invertebrates with latitude (presumably reflecting overall availability) in the summer diet of both adults and chicks. The few data on winter food suggest that invertebrates are of greater importance during the winter than during the summer (Ewins 1990). Breeding site Both early spring and breeding distributions appear to be influenced by the Hell Gate and Cardigan Strait polynya located in western Jones Sound, Canada, between Ellesmere and Devon islands. The evidence presented suggests that annual variation in the distribution of ice edges in Jones Sound may influence the distribution of breeding birds among suitable breeding habitat. The observed distribution of Guillemots in March, April, and May is coincident with the location of open water and the associated ice edges. Thereafter, as the ice margin recedes and shoreleads open, the distribution of Guillemots tends to reflect the location of breeding colonies (Prach and Smith 1992). Foraging range Birds feeding in the eastern Canadian Arctic fed principally in waters 10-130 m deep (Cairns 1987a). Birds have been caught in nets up to 50 m deep, but have a theoretical maximum dive of 130 m. They have been observed actively feeding in water 35-45 m deep (Uspenski 1956). However, in Kattegatt, Denmark, approximately 80% of all Black Guillemots were recorded in water with depths of 10-30 m (Durinck et al. 1994). Black Guillemots were always recorded less than 5 km from the coast of Caithness, Scotland during May-July (BirdLife International 2000). At the Bay of Fundy, Canada, almost all birds remained within 300 m of the shore (Ronconi and St. Clair 2002). At Papa Westray, Scotland, the mean foraging distance was 2.4 km away from the colony, and birds were recorded foraging in areas up to 3.9 km away from the colony, but despite this large variation in foraging range, feeding sites were never located further than 1.5 km from the shore (BirdLife International 2000). At Rockabill, Ireland, birds forage within 1 km of the colony or else fly 7km or more to reach the mainland coast (BirdLife International 2000). In the eastern Canadian Arctic, censuses indicated that most birds were feeding within 13 km of breeding colonies, with a few found as far as 15 km (BirdLife International 2000). Sightings were frequently highest within 5 km of the colony (BirdLife International 2000). Several studies (at the Bay of Fundy, Finland, Denmark and Iceland) found that Black Guillemots foraged between 0.5 and 4 km from nest sites, and occasionally beyond 7 km away (BirdLife International 2000). By contrast, in the NW Territories, Canada, breeding adults rarely foraged close to the colony, and some birds may have been travelling as far as 55 km (BirdLife International 2000). Birds probably capture some prey in the water column, but forage principally on benthic prey (Cairns 1987a). In Shetland, birds tend to forage where the sea bed is rocky and vegetated with dense stands of kelp (Laminaria spp.) (Ewins 1990) which reflects the habitat preferences of their main prey (BirdLife International 2000).

Related state of the world's birds case studies

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).

Brazil, M. 2009. Birds of East Asia: eastern China, Taiwan, Korea, Japan, eastern Russia. Christopher Helm, London.

Cairns, D.K. 1987. The ecology and energetics of chick provisioning by black guillemots. Condor 89: 627-635.

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

Durinck, J., Skov, H., Jensen, F.P. and Pihl, S. 1994. Important marine areas for wintering birds in the Baltic Sea. Ornis Consult, Copenhagen, Denmark.

Ewins, P.J. 1990. The diet of black guillemots Cepphus grylle in Shetland. Holarctic Ecology 13: 90-97.

Greenwood, J. G. 2007. Earlier laying by Black Guillemots Cepphus grylle in Northern Ireland in response to increasing sea-surface temperature. Bird Study 54: 378-379.

Harris, M.P. and Riddiford, N.J. 1989. The food of some young seabirds on Fair Isle in 1986-88. Scottish Birds 15: 119-125.

Prach R.W., Smith A.R. 1992. Breeding Distribution and Numbers of Black Guillemots in Jones Sound, N.W.T. . Arctic 45(2): 111-114.

Ronconi, R. A., St. Clair, C. C. 2002. Management options to reduce boat disturbance on foraging black guillemots (Cepphus grylle) in the Bay of Fundy . Biological Conservation 108(3): 265-271.

Uspenski. 1956. The bird bazaars of Novaya Zemlya. Russian Game Reports 4: 1-159.

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

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

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

Recommended citation
BirdLife International (2014) Species factsheet: Cepphus grylle. Downloaded from on 20/04/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from on 20/04/2014.

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.

Key facts
Current IUCN Red List category Least Concern
Family Alcidae (Auks)
Species name author (Linnaeus, 1758)
Population size mature individuals
Population trend Increasing
Distribution size (breeding/resident) 2,120,000 km2
Country endemic? No
Links to further information
- Additional Information on this species