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Crested Auklet Aethia cristatella

Justification
This species has a very 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). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to 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#.
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.
del Hoyo, J.; Collar, N. J.; Christie, D. A.; Elliott, A.; Fishpool, L. D. C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Barcelona, Spain and Cambridge UK: Lynx Edicions and BirdLife International.

Distribution and population
The Crested Auklet can be found in the north-west Pacific Ocean, specifically in the Bering Sea and Sea of Okhotsk (del Hoyo et al. 1996).

Population justification
The global population is estimated to number > c.8,200,000 individuals (del Hoyo et al. 1996), while the population in Russia has been estimated at < c.10,000 breeding pairs (Brazil 2009).

Trend justification
The population is suspected to be in decline owing to predation by invasive species, disturbance and pollution (del Hoyo et al. 1996).

Ecology
This species can be found offshore and along sea coasts, breeding on remote islands and coasts utilizing scree slopes, boulder fields, lava flows and sea cliffs. It forages in deep water, usually far often shore, and concentrating on areas with dense aggregations of zooplankton (e.g. areas of converging currents or upwellings). It usually occurs in large flocks. Its diet comprises mainly of planktonic crustaceans and infrequently small fish and squid. Individuals arrive at colonies between March and May, with the peak laying time varying depending on locality. Individuals are monogamous with high mate and site fidelity, and both sexes prefer mates with larger crests. Nest density in its sometimes large colonies (over 100,000 pairs) is determined by the availability of suitable rock crevices and cavities for nesting. Outside the breeding season it remains in the north-west Pacific (del Hoyo et al. 1996).

Related state of the world's birds case studies

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

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

Kitaysky, A. S.; Golubova, E. G. 2000. Climate change causes contrasting trends in reproductive performance of planktivorous and piscivorous alcids. Journal of Animal Ecology 69: 248-262.

Further web sources of information
Explore HBW Alive for further information on this species

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

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

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

Recommended citation
BirdLife International (2014) Species factsheet: Aethia cristatella. Downloaded from http://www.birdlife.org on 27/08/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 27/08/2014.

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 (Pallas, 1769)
Population size mature individuals
Population trend Decreasing
Distribution size (breeding/resident) 412,000 km2
Country endemic? No
Links to further information
- Additional Information on this species