48 USGS/BRD/ITR-2000-0012 



In 1993-95, all colonies were surveyed, but aerial 

 photographs were counted only at False Klamath Rock, 

 Flatiron Rock, False Cape Rocks, and Cape Vizcaino 

 (Carter et al. 1996; Appendix D). Combined murre 

 numbers at these colonies increased from 1989 to 1995, 

 despite the severe 1992-93 El Nino when most murres 

 abandoned colonies, except at Cape Vizcaino. At False 

 Klamath Rock, little change occurred between 1986 

 and 1995. By 1995, all four colonies had reached their 

 highest recorded levels, exceeding peak counts in 

 1979-82 (Figure 2.5; Appendixes C and D). At Redding 

 Rock, numbers of murres observed during aerial 

 photographic surveys have declined from 1989 to 1995, 

 although photographs have not been counted. This 

 colony may be extirpated in the near future because of 

 chronic human disturbance by U.S. Coast Guard 

 personnel. 



Population stability or limited increase in northern 

 California from 1 979 to 1 995 may have resulted from 

 three main factors, this region may be nearing the murre 

 carrying capacity of available breeding habitat and prey 

 resources, severe El Ninos and other natural events have 

 not had long-term effects, and anthropogenic effects 

 have not been extensive. Murres currently use much of 

 the available and suitable breeding habitat on all large 

 islands in Del Norte and Humboldt counties, although 

 breeding densities could increase further (see Appendix 

 I). The only large islands with substantial breeding 

 habitat that lack murre colonies north of Cape Vizcaino 

 are Hunter Rocks, Prince Island (at the Smith River), 

 and Sugarloaf Island. Although all three islands have 

 colonies of Brandt's cormorants, past and present human 

 disturbance may prevent breeding by murres. In 1912, 

 Prince Island and Hunter Rocks were assigned to the 

 Tolowa tribe, and native people periodically visit these 

 islands. Sugarloaf Island is occasionally visited by 

 climbers and low overflights occur frequently. Human 

 disturbance has occurred regularly at Redding Rock, 

 but has not been well documented (Lowe 1993). During 

 surveys in May (1980 and 1989), murres were observed 

 being flushed from Green Rock and False Cape Rocks 

 by U.S. Coast Guard aircraft flying at or below 152 m 

 (500 feet) elevation (Sowls et al. 1980; Carter et al. 

 1992, unpublished survey data). Few predators are 

 known to affect murres at northern California colonies. 

 Few peregrine falcons and bald eagles (Haliaeetus 

 leucocephalus) are present, although numbers of falcons 

 have been increasing. On several dates in 1980, 

 extensive egg predation by common ravens was noted 

 at False Klamath Rock, causing colony disruptions 

 (Sowls et al. 1980; unpublished survey data). Although 

 few oil spills occurred in northern California by 1995, 

 two recent oil spills near Humboldt Bay (1997 Kure 



and 1 999 Stuyvesant) killed large numbers of murres (P. 

 R. Kelly, personal communication). 



High numbers of breeding birds at colony complexes 

 at Cape Mendocino and Trinidad Area may have 

 contributed to the production of source birds that 

 recolonized the Cape Vizcaino and Rockport Rocks 

 colonies between 1969 and 1989. Between 1877 and 

 1942, log loading operations at and around Cottaneva 

 Wharf, which extended directly onto Rockport Rocks, 

 probably caused the earlier extirpation of these colonies 

 (Appendix B). Recolonization and subsequent growth 

 at the Cape Vizcaino colony complex may have 

 contributed to the production of source birds for more 

 recent colony formations at Newport Rocks, Kibesillah 

 Rock, and Goat Island in the mid-1990s. Such colony 

 formations in Mendocino County apparently occurred 

 over several decades of favorable conditions. 



Oregon 



Historical Background on Breeding Colonies 

 in Oregon, Prior to 1980 



Before the arrival of settlers from Europe and the 

 United States, native people occupied many locations 

 along the Oregon coast. Shellfish, fish, seabirds, and 

 marine mammals were of great importance in the diet of 

 native people (Berreman 1944; Heflin 1966; Gould 

 1966, 1976; Zontek 1983; Minor et al. 1987; Lyman 

 1988, 1989, 1991; Card 1990, 1992). Large mainland 

 village sites were associated with offshore rocks (Chase 

 1873; Schumacher 1877a, 1877b; Berreman 1944; Ross 

 1977). The pursuit and harvest of these food resources 

 by native people undoubtedly had great influence on 

 seabird colonies. Native people may have regularly 

 visited certain accessible murre colonies (especially near 

 village sites) by canoe to obtain eggs or birds. All known 

 colonies are located close to former village sites or 

 seasonal camps (Figure 2.7). Even colonies 4.8-6.4 m 

 (3^4- miles) offshore on Orford Reef (i.e., Redfish Rocks, 

 Colony numbers 270-043 to 270-047; Figure 2.7) could 

 have been reached by local residents during calm ocean 

 periods and were probably exploited on occasion for 

 food. 



Some rocks and islands were actually occupied by 

 native people, at least seasonally. At Goat Island, 

 shellfish remains were the most common items found in 

 a large midden (radiocarbon dated to 880 70 b.p.), 

 along with small numbers of bones of marine mammals, 

 fish, and seabirds (though not murres; Card 1990, 1992). 

 Murres probably did not breed on Goat Island during 

 coastal occupation by native peoples because the entire 

 island is easily accessible to humans. Seasonal 



