Population size, trends, and conservation problems of the Double-Crested Cormorant on the Pacific Coast of North America

Colonial Waterbirds
By: , and 

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Abstract

Population size, trends and conservation problems of the Double-crested Cormorant (Phalacrocorax auritus) were collated for the Pacific coast of North America using available data up to 1992. About 54,942 birds currently breed there, including roughly 5,848 (5,622 at 90 coastal colonies and at least 226 at 5 interior colonies) and 49,094 (43,358 at 126 coastal colonies and at least 5,736 at 22 interior colonies) for subspecies P. a. cincinatus in Alaska and P. a. albociliatus, from British Columbia to Sinaloa (Mexico), respectively. In addition, 51 and 22 inactive colonies have been documented in coastal and interior regions, respectively. Major historical declines (in the 1800s and early 1900s) occurred in much of Alaska, California, and Mexico, followed by increases in British Columbia, Washington, Oregon and California from the 1920s to 1980s. Recent declines are occurring in British Columbia, Washington, and Baja California. Trends are affected by apparent movements of nesting birds during El Niño oceanographic conditions and due to habitat loss at interior colonies, as well as recent use of artificial nesting habitats in some areas. Conservation problems have included various forms of human disturbance and persecution, marine pollutants, and high levels of predation owing to introduced and natural predators.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Population size, trends, and conservation problems of the Double-Crested Cormorant on the Pacific Coast of North America
Series title Colonial Waterbirds
DOI 10.2307/1521540
Volume 18
Issue 1
Year Published 1995
Language English
Publisher Waterbird Society
Contributing office(s) Patuxent Wildlife Research Center
Description 27 p.
First page 189
Last page 215
Country Canada, Mexico, United States
State Alaska, California, Oregon, Washington
Other Geospatial Pacific Coast of North America