BIOLOGY AND CONSERVATION OF THE COMMON MURRE 45 



Funds from the settlement of the Apex Houston oil 

 spill litigation were used for a restoration project at the 

 Devil's Slide Rock and Mainland colony (Graham 1996; 

 Parker et al. 1997, 1998, 1999; Helmuth 1999; Parker 

 1999). Breeding did not occur at this colony between 

 1986 and 1995. Using social attraction techniques, the 

 USFWS, Humboldt State University, and the National 

 Audubon Society restored breeding by small numbers 

 of murres at this colony in 1996-2000 (i.e., increasing 

 to 98 breeding pairs by 2000) 



The southernmost colony at Hurricane Point Rocks 

 also did not increase significantly between 1987 and 

 1 995. The increase in the Castle-Hurricane complex in 

 1993-95 has occurred mainly at the Castle Rocks and 

 Mainland colony. Both of these colonies are 

 geographically isolated from other colonies in central 

 California, were affected greatly during the decline, and 

 remain susceptible to extirpation. Slow recovery at these 

 colonies by 1995 may reflect poor breeding success, 

 immigration, and continued anthropogenic effects 

 (especially gill-net deaths and human disturbance; Julian 

 and Beeson 1995; Carter et al. 1998; McChesney et al. 

 1999; M. W. Parker, unpublished data). Establishment 

 of the California Islands Wildlife Sanctuary in 1983, 

 which prohibited disturbance of seabirds and marine 

 mammals, may have reduced human disturbance at the 

 Castle-Hurricane and Devil's Slide colony complexes. 

 In 1992, the Castle-Hurricane and Devil's Slide 

 complexes were provided more protection from human 

 disturbance through the creation of the Monterey Bay 

 National Marine Sanctuary that prohibited most 

 overflights below 305 m (1,000 feet). However, 

 disturbances from low-flying aircraft still continue. 

 Depredation by peregrine falcons does not seem to be 

 seriously affecting these colonies (M. W. Parker, 

 unpublished data). 



In central California, slow population recovery 

 since 1 990, and no recovery at certain colonies, probably 

 resulted from long-term and extensive anthropogenic 

 effects, especially mortality from gill nets and oil spills 

 and human disturbance from 1979 to 1987. Natural 

 factors (i.e., reduced breeding effort and success during 

 the severe 1982-83 El Nino) contributed to the decline 

 and also increased recovery time. Between 1988 and 

 1995, the effects of deaths from gill-nets and oil-spills 

 continued, but at reduced levels compared to 1982-88 

 (Julian and Beeson 1995; Sydeman et al. 1997; 

 McChesney et al. 1998, 1999). High breeding success 

 at the South Farallon Islands has occurred throughout 

 1979-95, except during severe El Ninos in 1983-84 

 and 1992-93 (Boekelheide et al. 1990; Sydeman et al. 

 1997). Thus, the increase seems mainly a result of 

 reduced anthropogenic factors. However, continuing 



low-level anthropogenic effects from oil pollution, 

 gill-net fishing, and human disturbance may limit 

 recovery. Reduced breeding effort and success during 

 recent El Ninos (i.e, 1992-93 and 1997-98) also may 

 slow the rate of recovery. If long-term climate change 

 has caused a significant reduction of prey resources, 

 this factor also may have influenced changes observed 

 and slowed recovery during the 1990-95 period. 



Population Trends in Northern California, 

 1979-1995 



From 1979 to 1982, numbers of murres attending 

 many colonies in northern California increased (Figures 

 2.5 and 2.6; Appendix C; Sowls et al. 1980; Briggs et 

 al. 1983). Increases were noted at all colony complexes, 

 except Trinidad (including Flatiron and Green rocks) 

 which remained relatively stable despite much variation 

 at individual colonies. Some methodological 

 differences between researchers in 1979-80 (Sowls et 

 al. 1980) and 1980-82 (Briggs et al. 1983) may have 

 slightly affected survey results reported for these two 

 periods. In addition, 1981 data quality may have been 

 lower at several colonies (K. T. Briggs, personal 

 communication). 



Few anthropogenic or natural factors were 

 documented to affect colonies in northern California at 

 this time. In 1980, Castle Rock received protection 

 through designation as a National Wildlife Refuge, 

 although occasional low overflights may have 

 continued. Both False Klamath Rock and Sister Rocks 

 are located within Redwood National Park, which may 

 have contributed to some disturbance from low 

 overflights related to park viewing. Variations in 

 numbers of murres counted at Redding Rock in 1979- 

 82 (Appendix C) probably reflected disturbance from 

 U.S. Coast Guard crews servicing an automated light on 

 this site during the breeding season. This source of 

 disturbance was first noted in 1979 (Sowls et al. 1980; 

 unpublished survey data), but probably occurred earlier. 

 In addition, California sea lions (Zalophus 

 californianus) "haul out" high up on this rock and may 

 adversely affect breeding success of murres in some 

 years (see Appendix I: Figure I- 1 8; H. R. Carter and M. 

 W. Parker, personal observations). Variable patterns 

 within the Trinidad complex appear to represent 

 intercolony movements between five nearby colonies. 

 In fact, corresponding changes in murre numbers at 

 Flatiron Rock and Green Rock (i.e., two large and 

 adjacent colonies in the Trinidad complex) were 

 recorded between May and July surveys in 1980-82 

 (Figure 2.5; Appendix C). Reasons for intercolony 

 movements were not determined, but hundreds of small 

 dead murre chicks were found on Flatiron Rock on 



