60 USGS/BRD/ITR-2000-0012 



1987-88 El Nino (Wilson 1991). From 1988 through 

 1995, natural and severe anthropogenic factors acted in 

 concert to affect the murre population. In December 

 1988, an estimated 30,000 murres were killed off the 

 outer Washington coast as a result of the Nestucca oil 

 spill (Ford et al. 1991). Because large numbers of murres 

 from breeding colonies in Oregon, and possibly British 

 Columbia, are found along the Washington coast during 

 the fall and winter months (Manuwal and Carter 2001 ), 

 these deaths probably involved murres originating from 

 colonies in Washington and other areas. The proportion 

 of murres from each area of origin killed by the Nestucca 

 spill is unknown. Following the July 1991 Tenyo Maru 

 spill, Warheit (1996) estimated that 39-58% of the adult 

 murres killed by this spill originated from Washington. 

 Based on estimates of total mortality (3,740-19,559 

 murres), the Tenyo Maru Oil Spill Natural Resource 

 Trustees (2000) concluded that a sizable portion of the 

 total Washington state murre population (including 

 nonbreeding adult, subadult, and juvenile birds) may 

 have been killed in the spill. 



Between 1991 and 1994, onboard observer 

 programs in various Washington gill-net fisheries 

 documented seabird deaths from entanglements. Further 

 studies in selected Puget Sound fisheries confirmed that 

 common murres represented the majority of the total 

 seabird entanglement (Jefferies and Brown 1 993; Erstad 

 et al. 1994; Pierce et al. 1994). In addition to deaths 

 from oil spills and gill nets documented in the early 

 1990s, low colony attendance and reduced breeding 

 effort occurred in 1993 during the severe 1992-93 El 

 Nino. By 1994-95, small numbers still attended colonies 

 in the Point Grenville complex but almost no birds 

 attended the Willoughby-Split complex. At these low 

 levels, it is doubtful if any murre breeding was still 

 occurring in southern Washington. 



In summary, numbers of murres attending colony 

 complexes in southern Washington declined 25.5% per 

 annum between 1979 and 1 995 (P<0.001; Figure 2.12; 

 Appendix H). Several types of anthropogenic and 

 natural factors apparently acted in concert to greatly 

 affect the population and prevent recovery. These 

 include severe El Ninos, chronic human disturbance, 

 and direct deaths from oil spills and gillnet 

 entanglement. These factors presumably resulted in low 

 colony attendance, reduced breeding success and 

 recruitment, increased movements within and outside 

 colony complexes, and deaths at sea. Since the southern 

 Washington population constituted 86% of the entire 

 Washington population in 1979-82, this change 

 represents loss of most of the breeding population of 

 murres within the state of Washington. Thus, overall 

 numbers of breeding murres in Washington also declined 



13.3% per annum between 1979 and 1995 (P = 0.002; 

 Figure 2.10). The factors affecting the three largest 

 colonies (Grenville Arch, Willoughby Rock, and Split 

 Rock) are largely responsible for the Washington murre 

 decline. Whereas murre colony attendance during 

 severe El Nino years is generally reduced (Wilson 1991 ) 

 because of changes in the marine food chain (Wooster 

 and Fluharty 1985), the manner in which anthropogenic 

 and natural factors acted to contribute to the decline, 

 and how they may have prevented recovery, are difficult 

 to determine with available evidence. 



Population Trends in Northern Washington, 

 1979-1995 



Between 1979 and 1982, numbers of murres 

 attending colonies varied extensively at individual 

 colonies, colony complexes, and overall in northern 

 Washington (Figures 2.11 and 2.13; Appendixes F, G, 

 and H). As in southern Washington, widespread colony 

 abandonment occurred in association with the severe 

 1982-83 El Nino (Wilson 1991). Colony attendance at 

 the Quillayute Needles complex returned to 1979-82 

 levels (excluding 1981) between 1987 and 1995 

 (Appendix H). This increase may have reflected return 

 of some breeding birds which had not attended colonies 

 during surveys in 1 983-84 or movements of birds from 

 other colony complexes. At the Carroll-Jagged 

 complex, substantial increase and more regular 

 attendance occurred in 1987-95 than in 1979-86. At 

 this complex, there was an apparent shift of birds from 

 Jagged Island to Carroll Island. U. W. Wilson 

 (unpublished data) considered no birds to be breeding 

 at Carroll Island in 1995, although egg laying and 

 breeding-site failure may have occurred prior to surveys. 

 The lack of recovery at Rounded Island colonies, 

 located closest to southern Washington, may have 

 reflected similar conditions as experienced in southern 

 Washington including a combination of effects from 

 natural and anthropogenic factors. With the exception 

 of Navy practice bombing, the same factors affecting 

 murres in southern Washington also affected the 

 northern colonies (e.g., severe El Ninos and gill-net and 

 oil-spill deaths). 



At Tatoosh Island and associated rocks (Colony 

 numbers 022, 023, 035), aerial photographic surveys 

 were not conducted until 1994-95 when moderate 

 numbers were recorded. Murres have been reported at 

 this colony since 1956 (Speich and Wahl 1989). Paine 

 et al. (1990) reported fewer than 1,000 birds during 

 1956-79, with a sharp increase to 2,000 birds during 

 the early 1980s. Briggs et al. (1992) reported 830 birds 

 in 1989. By 1992, islandwide attendance reached 3,871 

 birds, based on ground counts, ground estimates, and 



