BC Conservation Data Centre: Species Summary
Nannopterum auritum
Double-crested Cormorant
| Scientific Name: | Nannopterum auritum (Lesson, 1831) | ||||||||||
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| Scientific Name Synonyms: |
Phalacrocorax auritus
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| English Name: | Double-crested Cormorant | ||||||||||
| Classification / Taxonomy | |||||||||||
| Scientific Name - Concept Reference: | American Ornithologists' Union (AOU). 1998. Check-list of North American birds. Seventh edition. American Ornithologists' Union, Washington, D.C. [as modified by subsequent supplements and corrections published in The Auk]. Also available online: http://www.aou.org/. | ||||||||||
| Classification Level: | Species | ||||||||||
| Species Group: | Vertebrate Animal | ||||||||||
| Species Code: | B-DCCO | ||||||||||
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| Conservation Status / Legal Designation | |||||||||||
| Global Status: | G5 (Apr 2016) | ||||||||||
| Provincial Status: | S3S4 (Mar 2015) | ||||||||||
| BC List: | Blue | ||||||||||
| Provincial FRPA list: | |||||||||||
| Provincial Wildlife Act: | |||||||||||
| COSEWIC Status: | Not at Risk (May 1978) | ||||||||||
| SARA Schedule: | |||||||||||
| General Status Canada: | 4 - Secure (2005) | ||||||||||
| Migratory Bird Convention Act: | |||||||||||
| Ecology & Life History | |||||||||||
| General Description: | |||||||||||
| Global Reproduction Comments: | Time of nesting varies geographically, with local variations, and among different years a particular colony. Nesting begins in winter in Florida, as late as early June in southern Alaska. Clutch size usually one to seven (average typically three or four). Incubation 24-33 days (average around 28-30), by both sexes in turn. Hatching success was 54-75% in three studies. Survival from hatching to fledging was 72-95% in two studies. First flight to water at about 35-42 days. Independent at about 9-10 weeks. Usually first breeds at three years, sometimes at two years, rarely at one year. Renesting following loss of clutch is fairly common. Nest in relatively dense colonies; nests only 0.6 - 2.0 meters apart (Hatch and Weseloh 1999). New colonies may be abandoned within a few years, but once well established, likely to persist (Hatch and Weseloh 1999). See Johnsgard (1993) for further information. | ||||||||||
| Global Ecology Comments: | Typically forages within about 20 km of roost site (Johnsgard 1993). No available information on interannual fidelity to colony; median distance of breeding birds to their natal site was < 25 kilometres (Dolbeer 1991). Increased sea surface temperatures, such as those associated with El Nino events, were correlated with decreases in nesting populations in Washington (Wilson 1991). Vigorously defends eggs and young against avian predators (Ehrlich et al. 1992), though large gulls, crows, and ravens are significant predators on eggs and young in some areas. | ||||||||||
| Migration Characteristics: (Global / Provincial) | |||||||||||
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Nonmigrant: Local Migrant: Distant Migrant: Within Borders Migrant: |
Y / Y / Y / na / |
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| Global Migration Comments: | Northern coastal and especially interior populations migrate southward for nonbreeding season; migratory tendency is stronger on east coast than on west coast. Usually follows river valleys, coastlines, and water courses. Migrates day or night (Palmer 1962). East of the Rockies, migrates southward from northern latitudes in October-November, northward in April-May; breeders from the central and eastern parts of Canada and the northern U.S. winter mainly in the southern U.S. between Texas and Florida, with considerable overlap of different breeding populations on the wintering grounds; there is little intermixing of birds from east and west of the Rockies (Dolbeer 1991). | ||||||||||
| Habitats: (Type / Subtype / Dependence) |
Anthropogenic / Urban/Suburban / Facultative - occasional use
Forest / Conifer Forest - Mesic (average) / Facultative - occasional use Lakes / Lake / Facultative - occasional use Ocean / Intertidal Marine / Facultative - occasional use Ocean / Marine Island / Facultative - frequent use Ocean / Sheltered Waters - Marine / Facultative - frequent use Ocean / Subtidal Marine / Facultative - frequent use Other Unique Habitats / Estuary / Facultative - frequent use Rock/Sparsely Vegetated Rock / Cliff / Facultative - frequent use Rock/Sparsely Vegetated Rock / Rock/Sparsely Vegetated Rock / Facultative - frequent use Stream/River / Stream/River / Facultative - occasional use |
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| Global Habitat Comments: | Lakes, ponds, rivers, lagoons, swamps, coastal bays, marine islands, and seacoasts; usually within sight of land. Nests on the ground or in trees in freshwater situations, and on coastal cliffs (usually high sloping areas with good visibility). See Spendelow and Patton (1988) for further details on nesting sites in different geographic areas. | ||||||||||
| Food Habits: |
Piscivore: Adult, Immature
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| Global Food Habits Comments: | Feeds opportunistically on fishes (usually less than 13 cm long); dives from surface of water; usually feeds in water < 15 m deep. Accused of reducing sport fish populations in New York, but this contention has not been documented (Carroll 1988). Eats mostly schooling fishes (in marine waters, mainly slow-moving species of bottom and mid-water), sometimes aquatic invertebrates and rarely small vertebrates other than fishes. Sometimes forages in compact flocks. | ||||||||||
| Global Phenology: |
Crepuscular: Adult, Immature
Diurnal: Adult, Immature |
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| Provincial Phenology: (1st half of month/ 2nd half of month) |
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| Colonial Breeder: | Y | ||||||||||
| Length(cm)/width(cm)/Weight(g): | 81/ / 1818 | ||||||||||
| Elevation (m) (min / max): |
Global:
Provincial: |
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| Distribution | |||||||||||
| Endemic: | N | ||||||||||
| Global Range Comment: | BREEDING: southeastern Bering Sea and southern Alaska; southern British Columbia eastward through Manitoba to coastal Quebec and Newfoundland, south (in isolated colonies) to Baja California, coastal Sonora, central Chihuahua, central Durango, south-central Arizona, southern New Mexico, southern Texas, Gulf Coast, Florida, northern Bahamas, Cuba, Yucatan Peninsula, and Belize (Johnsgard 1993, AOU 1998). Breeding range in North America has expanded in recent years (Johnsgard 1993). Extirpated from Amchitka Island, Alaska, perhaps due to predation by arctic fox (ALOPEX LAGOPUS; Siegel-Causey et al. 1991). Occurs throughout most of the coastal breeding range and beyond when not breeding. NON-BREEDING: Pacific coast from Aleutians and southern Alaska south to Baja California and Nayarit; inland from Washington and Montana south to California and northeastern Colorado, southern Minnesota, and the Great Lakes south to northwestern Mexico, Oklahoma, Texas, and the Gulf states; and along the Atlantic coast, from Lake Ontario and New England south to Florida, Bermuda, the Bahamas, Greater Antilles, Yucatan Peninsula, and northern Belize (AOU 1998). | ||||||||||
| Authors / Contributors | |||||||||||
| Global Information Author: | HAMMERSON, G., REVISED BY S. CANNINGS | ||||||||||
| Last Updated: | May 17, 1995 | ||||||||||
| Provincial Information Author: | |||||||||||
| Last Updated: | |||||||||||
| References and Related Literature | |||||||||||
American Ornithologists' Union (AOU). 1983. Check-list of North American Birds, 6th edition. Allen Press, Inc., Lawrence, Kansas. 877 pp. |
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Buckley, P. A., and F. G. Buckley. 1984. Seabirds of the north and middle Atlantic coast of the United States: their status and conservation. Pages 101-133 in Croxall et al., eds. Status and conservation of the world's seabirds. ICBP Tech. Pub. No. 2. |
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Campbell, R.W., N.K. Dawe, I.McT. Cowan, J.M. Cooper, G. Kaiser, and M.C.E. McNall. 1990. The Birds of British Columbia, Vol. 1. Nonpasserines: Introduction, Loons through Waterfowl. Royal B.C. Mus. in association with Environ. Can., Can. Wildl. Serv. 514pp. |
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Carroll, J. R. 1988. Population growth of the double-crested cormorant (PHALACROCORAX AURITUS) and its potential for affecting sport fisheries in eastern Lake Ontario. New York Dept. Environ. Conserv., Delmar, NY. 12pp |
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Chapdelaine, G., and P. Brousseau. 1992. Distribution, abundance, and changes of seabird populations of the Gaspe Peninsula, Quebec, 1979-1989. Can. field-Nat. 106:427-434. |
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Conniff, R. 1991. Why catfish farmers want to throttle the crow of the sea. Smithsonian, July 1991, pp. 44-50, 52, 54-55. |
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DeBenedictis, P.A. 1989. Gleanings from the technical literature: recent studies on some water birds. Birding 21(3):166-168. |
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DeMauro, M. M. 1993. Colonial nesting bird responses to visitor use at Lake Renwick heron rookery, Illinois. Natural Areas Journal 13:4-9. |
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Dolbeer, R. A. 1991. Migration patterns of Double-crested Cormorants east of the Rocky Mountains. Journal of Field Ornithology 62:83-93. |
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Droege, S., and J.R. Sauer. 1990. North American Breeding Bird Survey, annual summary, 1989. U.S. Fish and Wildlife Service, Biological Report 90(8). 22 pp. |
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Ehrlich, P. R., D. S. Dobkin, and D. Wheye. 1992. Birds in Jeopardy: the Imperiled and Extinct Birds of the United States and Canada, Including Hawaii and Puerto Rico. Stanford University Press, Stanford, California. 259 pp. |
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Harrison, H. H. 1979. A field guide to western birds' nests. Houghton Mifflin Company, Boston. 279 pp. |
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Hatch, J. J., and D. V. Weseloh. 1999. Double-crested Cormorant (PHALACROCORAX AURITUS). No. 441 IN A. Poole and F. Gill, editors, The birds of North America. The Birds of North America, Inc., Philadelphia, PA. 36pp. |
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Hyslop, C., and J. Kennedy, editors. 1992. Bird trends: a report on results of national ornithological surveys in Canada. Number 2, Autumn 1992. Migratory Birds Conservation Division, Canadian Wildlife Service, Ottawa, Ontario. 20 pp. |
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Johnsgard, P. A. 1993. Cormorants, darters, and pelicans of the world. Smithsonian Institute Press, Washington, D.C. xiv + 445 pp. |
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Lensink, C. J. 1984. The status and conservation of seabirds in Alaska. Pages 13-27 in Croxall et al., eds. Status and conservation of the world's seabirds. ICBP Tech. Publ. No. 2. |
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Moul, I.E., and M.B. Gebauer. 2002. Status of the Double-crested Cormorant in British Columbia. B.C. Minist. Water, Land and Air Prot., Biodiv. Branch, Victoria, BC. Wildl. Working Rep. WR-105. 44pp. |
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Palmer, R. S. (editor). 1962. Handbook of North American birds. Vol. 1. Loons through flamingos. Yale University Press, New Haven. 567 pp. |
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Root, T. 1988. Atlas of wintering North American birds: An analysis of Christmas Bird Count data. University of Chicago Press. 336 pp. |
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Siegel-Causey, D. 1988. Phylogeny of the Phalacrocoracidae. Condor 90:885-905. |
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Siegel-Causey, D., C. Lefevre, and A. B. Savinetskii. 1991. Historical diversity of cormorants and shags from Amchitka Island, Alaska. Condor 93:840-852. |
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Spendelow, J. A. and S. R. Patton. 1988. National Atlas of Coastal Waterbird Colonies in the Contiguous United States: 1976-1982. U.S. Fish and Wildlife Service, Biological Report 88(5). x + 326 pp. |
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Terres, J. K. 1980. The Audubon Society encyclopedia of North American birds. Alfred A. Knopf, New York. |
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Vermeer, K., and S. G. Sealy. 1984. Status of the nesting seabirds of British Columbia. Pages 29-40 in Croxall et al., eds. Status and conservation of the world's seabirds. ICBP Tech. Pub. No. 2. |
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Wilson, U. W. 1991e. Responses of three seabird species to El Nino events and other warm water episodes on the Washington coast, 1979-1990. Condor 93:853-858. |
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Please visit the website Conservation Status Ranks for definitions of the data fields used in this summary report.
Suggested Citation:
B.C. Conservation Data Centre. 1995. Species Summary: Nannopterum auritum. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Dec 28, 2025).