Double-crested Cormorant
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| Double-crested Cormorant | ||||||||||||||
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| Phalacrocorax auritus (Lesson, 1831) |
The Double-crested Cormorant (Phalacrocorax auritus †) is a North American member of the cormorant family of seabirds.
This is a very common and widespread species. They breed in coastal areas as well as near inland rivers and lakes, building stick nests in trees, on cliff edges or on the ground on islands. They are gregarious birds, usually found in colonies, often with other aquatic birds. Their song is a deep, guttural grunt.
This bird feeds on the sea and fresh water lakes and rivers. It winters anywhere along the coasts that is well-supplied with fish.
This is a large black bird (29"-36"), with a wingspan up to 52". It has a long tail, yellow throat-patch, and can appear to have a green sheen in certain lighting. The white double head crest is seen for a short period during breeding season in western birds. It is duller in eastern birds. Juveniles are brown with a white face, foreneck, and breast.
Like all cormorants, the Double-crested dives to find its prey. It eats mainly fish, but also amphibians, crustaceans. This bird swims low in the water, often with just its neck and head visible, and dives from the surface. They use their feet for propulsion and are able to dive from 5-25 feet for 30-70 seconds.
After diving, these birds spend long periods standing with wings outstretched to allow them to dry, since they are not fully waterproofed. They fly low over the water, with their bills tilted slightly upward. They sometimes leaving their colony in long, single-file lines.
This species will migrate from the coldest parts of its range, such as eastern Canada, and has occurred in Europe as a very rare vagrant, for example in Great Britain, Ireland and the Azores.
This Double-crested Cormorant's numbers decreased in the 1960s due to the effects of DDT. Colonies have also been persecuted from time to time in areas where they are thought to compete with human fishing.
Folk names of this bird include Crow-duck, Farallon Cormorant, Florida Cormorant, lawyer, shag, and Taunton turkey.
- † Phalacrocorax: Latinized Greek for phalakros (bald) and kora (raven); auritus: Latin for eared.
Juvenile Double-crested Cormorants in winter, California
References
- Alsop, Fred J. III; Birds of Texas. Smithsonian Handbooks: DK Publishing, Inc., New York, NY (2002).
External links
- US Fish & Wildlife Service (http://migratorybirds.fws.gov/issues/cormorant/cormorant.html)nl:Amerikaanse aalscholver