Whole-Colony Counts of Common Murres, Brandt's Cormorants and Double-crested Cormorants at Sample Colonies in Northern and Central California, 1996-2004

• Main Authors: Phillip J. Capitolo, Gerard J. McChesney, Harry R. Carter, Micheal W. Parker, James N. Hall, Richard J. Young, Richard T. Golightly
• Format: Report
• Language: English
• Published: National Oceanic and Atmospheric Administration & U.S. Fish and Wildlife Service Agreement # MOA-2004-183/1274; U.S. Fish and Wildlife Service & Humboldt State University Foundation agreement # 14-48-0001-96502; Apex Houston Trustee Council; California Department of Fish and Game 2012
• Subjects: Common murre; Phalacrocorax penicillatus; Uria aalge; Colony counts; California; Brandt's cormorant; Double-crested cormorant; Phalacrocorax auritus; Aerial photographs; Breeding populations; Common Murre; uria
• Online Access: http://hdl.handle.net/2148/940

From 1996 to 2004, annual aerial photographic surveys of all northern and central California breeding colonies of Common Murres (Uria aalge), Brandt’s Cormorants (Phalacrocorax penicillatus), and Double-crested Cormorants (P. auritus) were conducted by the Common Murre Restoration Project (CMRP), in cooperation with the California Department of Fish and Game. These surveys have continued a long-term dataset (initiated in 1979) of whole-colony counts derived from aerial photographs; these counts have been used as indices of population size for estimation of breeding population size and for assessing long-term population trends. In this report, we present a summary of whole-colony counts in northern California for 1996 to 2004 and in central California for 2002 to 2004, and briefly discuss population status and general trends evident for murres and cormorants during these periods. For northern California, we counted all murre breeding colonies for 1997, 1999, 2001, 2003 and 2004, and certain sample murre colonies for other years. For central California, we counted all murre breeding colonies and other sample Brandt’s Cormorant colonies for 2002 to 2004. Numbers of California Brown Pelicans (Pelecanus occidentalis californicus) roosting within murre and cormorant colonies also were counted to provide information on use of coastal rocks by this endangered species during the late May and early June survey period. For Common Murres in northern California (defined as north of Point Reyes to the Oregon border; 38-42°N), a total of 211,421 birds were counted at 16 active colonies and one irregularly attended colony in 2004, corresponding to a rough estimate of 353,100 breeding individuals or 176,550 breeding pairs. The 2004 total count was 28% higher than the 2003 count, and total counts were similar in 1999, 2001, and 2003. Lower numbers in 1997 seemed to partly reflect reduced photograph quality. Less than 10% of the northern California murre population occurs in Mendocino County, but numbers there increased steadily ...