Ralph and others 



Chapter 1 



Overview of Ecology and Conservation 



Prince William Sound 



4 



NUMBER OF BIRDS 

 < 5,000 

 5,000 - 10,000 

 25,000 - 50,000 

 50,000 - 100,000 



Figure 1 Range of the Marbled Murrelet, which stretches from central California to southern Alaska, and 

 population size along sections of the coast. See table 2 for further details. 



characteristics allowing for adaptation to variability in these 

 environments. As an example, the waters between California 

 and the Aleutian Islands are partitioned into several dramatically 

 different regimes (Hunt, this volume a). The loss of these 

 peripheral populations would likely reduce diversity in the 

 population as a whole, and might reduce the capacity of the 

 species to adapt to long-term environmental changes. 



Distribution in Relation to Nesting Habitat 



During the breeding season, the distribution of the Marbled 

 Murrelet throughout its range is determined by the distribution 

 and accessibility of old-growth and late-successional 

 coniferous forests. Some evidence exists of a relationship 

 between the estimates of Marbled Murrelet population size, 



based on at-sea surveys, and the amount of old-growth forest 

 within a region. This relationship is most evident from 

 California to southern Washington, a coastline that is relatively 

 straight and contains disjunct pockets of old-growth forests. 

 In this region, the largest concentrations of murrelets at sea 

 during the breeding season are found along sections of coastal 

 waters that are adjacent to inland breeding areas (Nelson and 

 others 1992, Sowls and others 1980). Marine productivity is 

 high along this entire coast during summer (Ainley and 

 Boekelheide 1990), and access to suitable foraging areas 

 does not appear to limit murrelet distribution. Circumstantial 

 evidence is considerable that murrelet distribution is limited 

 by nesting, rather than foraging, habitat. For example, 

 murrelets concentrate offshore from old-growth areas during 



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



