Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Charadriiformes Alcidae

Scientific Name: Cerorhinca monocerata
Species Authority: (Pallas, 1811)
Common Name(s):
English Rhinoceros 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.
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:
2009 Least Concern (LC)
2008 Least Concern (LC)
2004 Least Concern (LC)
2000 Lower Risk/least concern (LR/lc)
1994 Lower Risk/least concern (LR/lc)
1988 Lower Risk/least concern (LR/lc)

Geographic Range [top]

Range Description: The Rhinoceros Auklet is found in the North Pacific and breeds from California, USA, off the coasts of Canada and Alaska to the Aleutian Islands in North America; and on Hokkaido and Honshu, Japan, as well as on the northern tip of North Korea, Sakhalin (Russia) and at two places on the far eastern Siberian coast in Asia (del Hoyo et al. 1996).
Countries occurrence:
Canada; China; Japan; Korea, Democratic People's Republic of; Korea, Republic of; Mexico; Russian Federation; United States
Continuing decline in area of occupancy (AOO): Unknown
Extreme fluctuations in area of occupancy (AOO): No
Estimated extent of occurrence (EOO) - km2: 321000
Continuing decline in extent of occurrence (EOO): Unknown
Extreme fluctuations in extent of occurrence (EOO): No
Continuing decline in number of locations: Unknown
Extreme fluctuations in the number of locations: No
Upper elevation limit (metres): 200
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: The global population is estimated to number > c.1,300,000 individuals (del Hoyo et al. 1996), while national population estimates include: < c.1,000 wintering individuals in Korea; c.10,000-1 million breeding pairs c.1,000-10,000 wintering individuals in Japan and c.10,000-100,000 breeding pairs in Russia (Brazil 2009).

Trend Justification:  The population is suspected to be in decline owing to predation by invasive species.
Current Population Trend: Decreasing
Additional data:
Continuing decline of mature individuals: Unknown
Extreme fluctuations: No Population severely fragmented: No
Continuing decline in subpopulations: Unknown
Extreme fluctuations in subpopulations: No All individuals in one subpopulation: No

Habitat and Ecology [top]

Habitat and Ecology: Habitat: This marine species cab ne found both offshore and along sea coasts and islands. It breeds on maritime and inland grassy slopes, sometimes on predator-free islands, and rarely on steep island or mainland cliffs. It occurs in large aggregations at sea, often forming dense roosting flocks at night in sheltered bays. In winter it is normally pelagic in waters offshore from breeding areas and sometimes in near-shore coastal waters where food is highly concentrated due to oceanographic conditions. Diet: It feeds mostly on fish throughout the year supplemented in winter by small amounts of invertebrates such as squid and krill. Chick diet it almost exclusively fish though also invertebrates for late-hatching young. Breeding: It arrives at colonies in late March and early April, laying from the end of April to mid-June. It is monogamous with high site and mate fidelity. It is highly colonial in small to very large concentrations sometimes over 100,000 individuals. Laying is often highly asynchronous within a colony. Birds lay in nest chambers at the end of a burrow which are excavated by both sexes (del Hoyo et al. 1996).
Systems: Terrestrial; Marine
Continuing decline in area, extent and/or quality of habitat: Unknown
Generation Length (years): 8
Movement patterns: Not a Migrant
Congregatory: Congregatory (and dispersive)

Citation: BirdLife International. 2012. Cerorhinca monocerata. The IUCN Red List of Threatened Species 2012: e.T22694924A38908071. . Downloaded on 10 October 2015.
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