Justification of Red List Category
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 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.
The global population is estimated to number more than 100,000 individuals, which equates to more than 67,000 mature individuals (del Hoyo et al. 1996).
The population is suspected to be in decline owing to predation by invasive species and ongoing habitat destruction.
The Whiskered Auklet is found in the north Pacific, from the north-east Sea of Okhotsk, the Commander and Kuril Islands (Russia), and throughout the Aleutian Islands (U.S.A.). It winters as far south as the eastern coast of Japan (del Hoyo et al. 1996).
This species is found offshore and along sea coasts in summer and is mostly pelagic in winter. Its diet includes a high variety of planktonic crustaceans, and infrequently small fish and squid. It forages mainly offshore in deep water, and sometimes in near-shore regions, almost always in large flocks, throughout the year. Birds arrive at colonies from March to June depending on the site. It is highly monogamous with high site and mate fidelity throughout its breeding life. Colonies form on remote islands and coasts in a variety of different rocky habitats. Densities are determined largely by the availability of suitable rock crevices and cavities for nesting (del Hoyo et al. 1996).
Survival and productivity of Whiskered Auklet populations have been shown to co-vary with continuous variation in large-scale climatic conditions, through indirect impacts on food supplies and negative effects of stormy North Pacific weather (Jones et al. 2007). However, productivity has also been found to be positively correlated with sea-surface temperature where studied (Jones et al. 2007), thus the future impacts of climate change remain uncertain.
Text account compilers
Butchart, S., Calvert, R., Ekstrom, J., Fjagesund, T., Martin, R. & Miller, E.
BirdLife International (2022) Species factsheet: Aethia pygmaea. Downloaded from http://www.birdlife.org on 05/07/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 05/07/2022.