Phalacrocorax auritus

Phalacrocorax auritus
Name	Double-crested Cormorant
Status	LC
Status system	IUCN3.1
Genus	Phalacrocorax
Species	auritus
Authority	(Lesson, 1831)

Phalacrocorax auritus

Phalacrocorax auritus, commonly called the double-crested cormorant, is a medium-to-large waterbird native to North America noted for its diving foraging and distinctive breeding plumage. It has attracted attention from ornithologists, conservationists, resource managers, and photographers across institutions such as the Smithsonian Institution, American Ornithological Society, Canadian Wildlife Service, and regional wildlife agencies. Studies by researchers affiliated with universities like Cornell University, University of British Columbia, McGill University, and University of California, Davis have examined its ecology, population dynamics, and interactions with fisheries.

Taxonomy and nomenclature

Described by René-Primevère Lesson in 1831, the species was placed in the genus Phalacrocorax, a taxon treated by authorities including the International Ornithologists' Union and the American Ornithological Society. Nomenclatural treatments have debated subspecies boundaries and nomenclature in revisions published in journals such as The Auk and Ibis, and molecular phylogenies by teams at Harvard University and the Natural History Museum, London have reassessed relationships among Phalacrocoracidae. Historic names applied in field guides by authors at Roger Tory Peterson Institute and publishers like Johns Hopkins University Press reflect regional vernacular variation documented by agencies including Environment and Climate Change Canada and the U.S. Fish and Wildlife Service.

Description

Adults show glossy black plumage with iridescent green or blue sheen in reports summarized in field guides from Audubon Society, Sibley Guides, and the National Audubon Society. During breeding, conspicuous tufts appear and were described in early accounts by naturalists associated with the Linnean Society of London and collectors in the collections of the National Museum of Natural History (France). Morphometrics measured by researchers at University of Minnesota and the Canadian Museum of Nature report body lengths and wingspans comparable to specimens cataloged at the American Museum of Natural History and the Field Museum. Vocalizations and visual displays have been analyzed by acousticians collaborating with the Macaulay Library and the Cornell Lab of Ornithology.

Distribution and habitat

The species breeds across inland and coastal regions of North America, with range assessments published by BirdLife International, the IUCN, and national atlases produced by NatureServe and provincial agencies such as Manitoba Conservation. Seasonal migrations connect breeding areas in the Great Lakes, Boreal forest margins, and Pacific coasts with wintering sites along the Gulf of Mexico, the Atlantic Coast (United States), and parts of the Caribbean. Habitat use in wetlands, estuaries, lakes, and reservoirs has been documented in management plans by U.S. Army Corps of Engineers, state departments like the New York State Department of Environmental Conservation, and conservation NGOs including The Nature Conservancy.

Behavior and ecology

Diving behavior, prey selection, and foraging ecology have been investigated in collaborative studies involving teams from University of Washington, University of Florida, and government labs at the National Oceanic and Atmospheric Administration. Diets include fish species monitored by agencies such as the National Marine Fisheries Service and provincial fisheries branches; interactions with commercial and recreational fisheries prompted policy analysis by entities like the International Association of Fish and Wildlife Agencies. Social roosting, colony dynamics, and interspecific interactions have been described in ecological literature appearing in journals including Ecology Letters and Journal of Avian Biology, and have been incorporated into management guidance by agencies such as Fish and Wildlife Service and provincial wildlife ministries.

Breeding and life cycle

Colonial nesting on islands, trees, and artificial structures has been subject to long-term monitoring projects run by organizations like Audubon Society, the Canadian Wildlife Service, and university research groups at University of Wisconsin–Madison and Simon Fraser University. Clutch size, incubation periods, and fledging success metrics have been reported in studies appearing in The Condor and coordinated through banding efforts by the North American Banding Council and regional bird observatories such as Point Reyes Bird Observatory. Parental care, nest construction using local materials recorded in museum archives at Royal Ontario Museum, and age-structured survival analyses have informed demographic models used by conservation planners at Bird Studies Canada.

Conservation status and threats

Classified as Least Concern by the IUCN Red List at continental scales, the species faces region-specific threats documented by the U.S. Fish and Wildlife Service, Environment Canada, and state agencies like the Michigan Department of Natural Resources. Mortality factors include entanglement and pollution issues investigated by teams at NOAA Fisheries and the Environmental Protection Agency, disturbance and habitat loss flagged by urban planners and port authorities such as Port of Seattle, and conflicts with aquaculture and aquaculture firms regulated under statutes enforced by agencies like National Oceanic and Atmospheric Administration Fisheries (NOAA) and provincial equivalents. Management responses range from nonlethal deterrents evaluated by researchers at University of Guelph to policy actions debated in forums organized by the North American Waterbird Conservation Plan and regional task forces involving municipal, provincial, and federal stakeholders.

Category:Phalacrocoracidae Category:Birds of North America