40 USGS/BRD/ITR-2000-0012 



i RockR 

 ' Sister Rocks 

 False Klamath Rock 



Redding Rock 



Sea Lion Rock 



White Rock 



Green Rock 



Mai, ion Rock 



Blank Hock 

 Pilot Rock 



False Cape Rock 



Sugarloat Island 



Steamboat Rock 



Kibesillah Rock 

 i Newport Rocks^ 



Goat Island Area 



1 Gualala Point Island 



50 Kilometers 



floe* attended w/o confirmed breeding 



Long-inactive colony 



" Recently-inactive colony 



Recently-formed colony 



Figure 2.1 . Distribution of common murre colonies in northern California 

 (Del Norte to Sonoma Counties). 



personal observation). Murres breed regularly at the 

 South Farallon Islands, Point Reyes, and Castle Rocks 

 and Mainland colonies where long-term studies of murre 

 biology and reproductive success are under way (see 

 Chapter 1; Boekelheide et al. 1990; Parker et al. 1997, 

 1998, 1999; McChesney et al. 1998, 1999). 



The entire breeding population of murres in 

 California was estimated in 1980, 1982, and 1989 (Sowls 

 et al. 1980; Briggs et al. 1983; Carter et al. 1992). On 

 the basis of summed, whole-colony counts for all 

 colonies, with a k correction factor, we calculated total 

 populations of 467,100, 514,900, and 351,600 breeding 

 murres in 1980, 1982, and 1989, respectively. The 

 central California population held 42, 43, and 26% of 

 the total in each of the 3 years surveyed, respectively. 

 The lower percentage in 1989 reflects extensive decline 

 in central California from 1982 to 1989, and little change 

 in northern California, except for lower revised estimates 

 at Castle Rock (see later). 



In central California, colonies can be grouped into 

 six colony complexes two offshore complexes at the 

 South and North Farallon Islands (about 20-30 km from 



the mainland) and four nearshore complexes (i.e., coastal 

 rocks within 1 km of the mainland and adjacent mainland 

 cliffs) at Point Reyes, Points Resistance-Double, Devil's 

 Slide, and Castle-Hurricane (Figure 2.2; Appendixes C 

 and D). The largest colony complex was the South 

 Farallon Islands where an estimated 1 02,700 murres bred 

 in 1982 (Table 2.1). Whole-colony counts at the South 

 Farallon Islands averaged 38,019 birds per survey from 

 1979 to 1995, which corresponded to an estimated 

 63,500 breeding birds (Table 2.1). Two other large colony 

 complexes were at the North Farallon Islands and Point 

 Reyes, which averaged 34,600 and 23,000 breeding 

 birds, respectively, during the same time period. 

 Breeding on inaccessible mainland points occurs only 

 at Point Reyes and Castle Rocks and Mainland. Three 

 smaller colonies (Point Resistance, Millers Point Rocks, 

 and Double Point Rocks) exist south of Point Reyes 

 within the Points Resistance-Double complex. Colonies 

 exist south of San Francisco at the Devil's Slide complex 

 (including the Devil's Slide Rock and Mainland colony 

 and the long-inactive colony at San Pedro Rock), as 

 well as at the Castle-Hurricane complex (Figure 2.2). 

 The southernmost colony in California in 1979-95 was 

 Hurricane Point Rocks. 



Point Resistance n 



Millers Point Rocks Point Reyes 



Double Point Rocks! 



North Farailon Islands- 

 South Farallon Islands 



San Pedro Rock 



A Devil's Slide Flock 5 Mainland 



'Pillar Point 



. Bench Mark-227x 

 Castle Rocks Mainland 

 Hurricane Point Rocks 



25 50 Kilometers 



1 flock attended iv/o confirmed breeding 



> Long-inactive colony 



> Recently-inactive colony 

 1 Recently-active colony 



San Miguel 

 Island 



Santa RosaV_J 

 Island 



Figure 2.2. Distribution of common murre colonies in central California 

 (Marin to Monterey Counties) and southern California (Santa Barbara 

 County). 



