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Aethia pusilla 

Scope: Global
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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Charadriiformes Alcidae

Scientific Name: Aethia pusilla
Species Authority: (Pallas, 1811)
Common Name(s):
English Least Auklet
Taxonomic Source(s): del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A. and Fishpool, L.D.C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Lynx Edicions BirdLife International.

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2012
Date Assessed: 2012-05-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Facilitator/Compiler(s): Ekstrom, J., Butchart, S., Calvert, R.
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). 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.
Previously published Red List assessments:

Geographic Range [top]

Range Description:The Least Auklet can be found in the northern Pacific Ocean. It ranges from Hokkaido, Japan and south-west Alaska (USA) in the south, up to and including the south of the Chukchi Sea. It breeds on the islands of Siberia, Russia and Alaska, as well as a few colonies on their coast (del Hoyo et al. 1996).
Countries occurrence:
Native:
Japan; Russian Federation; United States
Vagrant:
Canada
Additional data:
Continuing decline in area of occupancy (AOO):Unknown
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:65200
Continuing decline in extent of occurrence (EOO):UnknownExtreme fluctuations in extent of occurrence (EOO):No
Continuing decline in number of locations:Unknown
Extreme fluctuations in the number of locations:No
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:The global population is estimated to number > c.24,000,000 individuals (del Hoyo et al. 1996), while national population sizes have been estimated at c.50-10,000 wintering individuals in Japan and c.10,000-1 million breeding pairs in Russia (Brazil 2009).

Trend Justification:  The population is suspected to be in decline owing to predation by humans and invasive species, as well as the effects of disturbance and pollution (del Hoyo et al. 1996).
Current Population Trend:Decreasing
Additional data:
Continuing decline of mature individuals:Unknown
Extreme fluctuations:NoPopulation severely fragmented:No
Continuing decline in subpopulations:Unknown
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:No

Habitat and Ecology [top]

Habitat and Ecology:This marine species is found offshore and along coasts. It forages on planktonic crustaceans near-shore or offshore throughout the year, almost always in large flocks and in the open oceans where physical charachteristics cause high planktonic densities. Birds arrive at colonies in the spring, earliest towards the extreme south and latest in the north. It is monogamous with shared mate choice and relatively low mate fidelity between the years. Colonies of more than one million individuals may form on remote islands and sea coasts, nesting on talus slopes, beach boulder rubble, sea cliffs and lava fields where crevices are suitable for breeding (del Hoyo et al. 1996).
Systems:Terrestrial; Marine
Continuing decline in area, extent and/or quality of habitat:Unknown
Generation Length (years):6.9
Movement patterns:Not a Migrant
Congregatory:Congregatory (and dispersive)

Citation: BirdLife International. 2012. Aethia pusilla. The IUCN Red List of Threatened Species 2012: e.T22694921A38907217. . Downloaded on 06 December 2016.
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