Piatt and Naslund 



Chapter 28 



Abundance, Distribution, and Population Status in Alaska 



Marbled Murrelet Distribution 



April -- September 

 Prep, by J. Piatt / Research 



f-SS .00000 /KmSq jj||: .50000 /KmSq 



||i 1.0000 /KmSq ]|| 2.0000 /KmSi) 



JH 4.0000 /KmSq 8.0000 /KrnSq 



:: Sampled area 200 m contour 



30 ro contour 



Figure 5 Distribution of Marbled Murrelets around the Kodiak Archipelago in summer (April-September). Density contour 

 polygons calculated from data grouped in 5' latitude-longitude blocks and scaled geometrically. 



Southeast Alaska: 45,000-70,000; Northern Gulf Coast 

 (including Prince William Sound): 32,000-60,500; Kodiak 

 Archipelago: 7,000-13,000; Alaska Peninsula: 4,000-10,000. 

 Combining results of the Alaska-wide OCSEAP surveys, 

 and the more recent fine-scale surveys of Prince William 

 Sound and Cook Inlet, we conclude that Marbled Murrelet 

 populations in Alaska are in the low 10 5 category, possibly 

 around 280,000 individuals. One important implication of 

 the OCSEAP data is that only about 3 percent of the Alaskan 

 Marbled Murrelet population resides in wholly nonforested 

 regions during the breeding season. If we factor in the fine- 

 scale survey results, then the proportion of murrelets residing 

 in non-forested regions is further reduced to only 1 .4 percent 

 of the total Alaskan population. Presumably at least this 

 fraction of the population nests on the ground. Some murrelets 

 also nest on the ground in alpine habitat of forested areas 

 and, rarely, on the ground in forests (Ford and Brown 1994; 

 Kuletz, pers. comm.; Mendenhall 1992). 



Human Threats to Populations 



Logging of Old-Growth Nesting Habitat 



Aside from a small fraction that nest on the ground (see 

 above), most Marbled Murrelets in Alaska nest in old-growth 

 forests (Kuletz and others, this volume; Naslund and others 

 1993), and populations are therefore affected directly by 

 logging of these forests. Unlike factors leading to direct 

 mortality, such as oil spills and gill-nets, it is difficult to 

 quantify the impact of logging on murrelet populations. 

 However, it is obvious that logging of breeding habitat must 

 lead to an immediate reduction in murrelet production. If 

 murrelets do not, or can not, breed elsewhere in subsequent 

 years, then removal of habitat must eventually lead to reduced 

 population size as adults are culled over time from breeding 

 populations, but are not replaced by new recruits. The massive 

 (85-90 percent) reduction in old-growth nesting habitat in 

 California, Oregon, Washington, and British Columbia because 



290 



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



