Piatt and Naslund 



Chapter 28 



Abundance, Distribution, and Population Status in Alaska 



400 



300 



on H 



Q & 



& O 



I I fT. 



E 



fa W 



W 



200 



100' 



MURRELET NUMBERS 

 --PARTY-HOURS OF EFFORT 

 -0 BOAT-HOURS OF EFFORT 



1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 



YEAR 



Figure 7 Numbers of Marbled Murrelets observed on Christmas Bird Counts (CBC) at five coastal sites in Alaska (see text). 

 Numbers are 5-year running means of CBC data collected from 1972-1991. Survey effort (lines) also presented as 5-year 

 running means. 



Surveys in all years were conducted using similar protocols, 

 population estimates were relatively precise (37-47 percent 

 in winter, 16-32 percent in summer), and declines observed 

 on surveys conducted in summer were highly significant (P 

 < 0.01; Klosiewski and Laing 1994). Declines observed for 

 murrelets were paralleled by population declines in 15 other 

 marine bird species as well. These declines could not be 

 accounted for by losses from the Exxon Valdez oil spill, and 

 suggest that other large-scale factors have influenced marine 

 bird populations in Prince William Sound during the 20-year 

 interval between surveys (Klosiewski and Laing 1994). This 

 is consistent with observations on other marine animals in 

 the Gulf of Alaska (above). 



In summary, the bulk of Marbled Murrelet populations 

 in North America reside in Alaska. Most murrelets are 

 concentrated in areas containing large tracts of coastal old- 

 growth forests. Populations in Alaska have apparently declined 

 by more than 50 percent over the last 20 years. This decline 

 has presumably occurred in response to the cumulative effects 



of habitat loss (logging), gill-net mortality, oil pollution, and 

 natural changes in the marine environment. Life history 

 characteristics of the Marbled Murrelet predispose the species 

 to slow recovery from natural and anthropogenic perturbations, 

 and make it particularly vulnerable to factors which increase 

 adult mortality. 



Acknowledgments 



We thank Patrick Gould, Kate Wynne, and Chris Wood 

 (and the Burke Museum, University of Washington) for 

 access to unpublished data on murrelet bycatch in gill-nets. 

 We thank Peter Connors, Anthony DeGange, Douglas Forsell, 

 George Hunt Jr., David Irons, Karen Laing, Mike McAllister, 

 C. John Ralph, Larry Spear, and Steven Speich for thoughtful 

 reviews and discussions on the paper, and Mary Cody, Scott 

 Hatch, Kathy Kuletz, John Lindell, Dennis Marks, Suzann 

 Speckman, Alan Springer, and Gus van Vliet, for sharing 

 their insights about murrelets in Alaska. 



294 



USDA Forest Service Gen. Tech. Rep. PSW-152. 1995. 



