Our Liviiii; Rffiimnts — Birds 



4J 



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 Texas Tech University Press, Lubbock. 



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For further Information: 



William L. Hohman 



National Biological Service 



Southern Science Center 



700 Cajundome Blvd. 



Lafayette. LA 70506 



Moie than two million seabirds of 29 

 species nest along the west coasts of 

 Califoinia, Oregon, and Washington, including 

 three species listed on the federal list of threat- 

 ened and endangered species: the brown pelican 

 (Pelecanus occidentalis). least tern (Stcnia 

 antillaruni). and marbled murrelet 

 (Bnichynimphits marmoratiis). The size and 

 diversity of the breeding seabird community in 

 this region reflect excellent nearshore prey con- 

 ditions; subtropical waters within the southern 

 California Bight area; complex tidal waters of 

 Strait of Juan de Fuca and Pugel Sound in 

 Washington; large estuaries at San Francisco 

 Bay, Columbia River, and Grays Harbor- 

 Willapa bays; and the variety of nesting habitats 

 used by seabirds throughout the region, includ- 

 ing islands, mainland cliffs, old-growth forests, 

 and artificial structures. 



Breeding seabird populations along the west 

 coast have declined since European settlement 

 began in the late 1700's because of human 

 occupation of. commercial use of. and introduc- 

 tion of mammalian predators to seabird nesting 

 islands. In the I900"s. further declines occuned 

 in association with rapid human population 

 growth and intensive commercial use of natural 

 resources in the Pacific region. In particular. 

 severe adverse impacts have occurred from par- 

 tial or complete nesting habitat destruction on 

 islands or the mainland, human disturbance of 

 nesting islands or areas, marine pollution, fish- 

 eries, and logging of old-growth forests (Ainley 

 and Lewis 1974; Bartonek and Nettleship 1979; 

 Hunt et al. 1979; Sowls et al. 1980; Nettleship 

 et al. 1984; Speich and Wahl 1989; Ainley and 

 Boekelheide 1990; Sealy 1990; Ainley and 



Hunt 1 99 1 ; Carter and Morrison 1 992; Carter et 

 al. 1992; Vermeeret al. 1993). 



Methods 



Population status of breeding seabirds on the 

 west coast has been measured primarily through 

 the determination of and trends in population 

 size, based on counts of birds and nests at nest- 

 ing colonies (e.g., Sowls et al. 1980). At-sea 

 surveys also have been used to approximate 

 population sizes for breeding and nonbreeding 

 populations and species as well as their foraging 

 distribution alongshore and offshore (e.g.. 

 Briggs et al. 1987). Rather than just monitoring 

 siTiall plots of nests on a few accessible islands 

 to determine status and trends, relatively accu- 

 rate and standardized censuses of entire coastal 

 seabird breeding populations (except for certain 

 nesting areas of difficult-to-census species) 

 have been conducted annually or periodically to 

 determine the overall status of many species 

 breeding on the west coast (Figs. 1-4). 

 However, we have considered census accuracy, 

 natural variability, trends at well-studied 

 colonies (e.g.. Farallon National Wildlife 

 Refuge) and many other factors in assessing 

 population status and trends. 



Status and Trends 



Storm-petrels (Hydrobatidae) 



Increasing numbers of Leach's storm-petrels 

 (Oceanodroma leucorhoa) have been docu- 

 mented recently in Oregon (R.W. Lowe, 

 USFWS, unpublished data), although this 



Breeding 

 Seabirds in 

 California, 

 Oregon, and 

 Washington 



by 



Harry R. Carter 



David S. Gilmer 

 National Biological Service 



Jean E. Takekawa 



Roy W. Lowe 



Ulrich W. Wilson 

 U.S. Fish and Wildlife Service 



