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Double-crested Cormorant Phalacrocorax auritus

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). 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 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#.
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 Double-crested Cormorant is widely distributed across North America, from the Aleutian Islands and Alaska (USA) down to north-west Mexico on the Pacific coast, and from North Carolina (USA) down to Cuba on the Atlantic coast. Summer breeding grounds also include much of the United States and southern-central and eastern Canada1.

Trend justification
The overall population trend is increasing, although some populations may be stable and others have unknown trends (Wetlands International 2006). This species has undergone a large and statistically significant increase over the last 40 years in North America (2200% increase over 40 years, equating to a 120% increase per decade; data from Breeding Bird Survey and/or Christmas Bird Count: Butcher and Niven 2007).

Ecology
This species habitat ranges widely, including sheltered marine waters such as estuaries, bays and mangrove swamps, rocky coasts and coastal islands, and inland on lakes, rivers, swamps, reservoirs and ponds. Its diet it almost exclusively fish with a few crustaceans, with the prey species changing depending on locality. Prey is caught by pursuit-diving, and individuals can fish co-operatively, sometimes with thousands of birds together at one time. It begins laying from April to July, nesting on a wide variety of substrates forming colonies sometimes over thousands of pairs strong (del Hoyo et al. 1992).

References
del Hoyo, J.; Elliot, A.; Sargatal, J. 1992. Handbook of the Birds of the World, vol. 1: Ostrich to Ducks. Lynx Edicions, Barcelona, Spain.

Delany, S.; Scott, D. 2006. Waterbird population estimates. Wetlands International, Wageningen, The Netherlands.

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

Search for 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: Phalacrocorax auritus. Downloaded from http://www.birdlife.org on 29/12/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 29/12/2014.

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.

Additional resources for this species

ARKive species - Double-crested cormorant (Phalacrocorax auritus) 0

Key facts
Current IUCN Red List category Least Concern
Family Phalacrocoracidae (Cormorants)
Species name author (Lesson, 1831)
Population size mature individuals
Population trend Increasing
Distribution size (breeding/resident) 2,400,000 km2
Country endemic? No
Links to further information
- Additional Information on this species