Chapter 18 



A Landscape-Level Analysis of Marbled Murrelet Habitat in 

 Western Washington 



Martin G. Raphael 1 



John A. Young 2 



Beth M. Galleher 3 



Abstract: Relationships between landscape-level patterns of for- 

 est cover and occupancy by Marbled Murrelets in the state of 

 Washington where state-wide forest-cover information was avail- 

 able were investigated. Using a geographic information system, a 

 203-hectare circular area surrounding each of 261 previously 

 surveyed locations was delineated. Within each area, we calcu- 

 lated the amount, distribution, and pattern of various classes of 

 late-serai forest. Proportions of old-growth forest and large saw- 

 timber were greater at sites that were occupied by murrelets than 

 at sites where they were not detected. Mean size of patches 

 (contiguous cover) of old growth and large sawtimber were also 

 greater among occupied sites than among detected and undetec- 

 ted sites. On average, old growth and large sawtimber combined 

 comprised about 36 percent of occupied sites (203-ha areas) vs. 

 30 percent and 18 percent on detected and undetected sites, 

 respectively. Various indices of landscape pattern were less use- 

 ful in distinguishing these sites, but in general, occupied sites had 

 more complex patterns with more edge, a greater variety of cover 

 types, and more complex shapes (greater lengths of edge relative 

 to area of patches). Broader patterns, evaluated within large river 

 basins, are also described, but lack of consistent survey effort 

 among these basins precluded analyzing rates of occupancy in 

 relation to forest cover at that scale. 



Studies of murrelet nesting behavior in the Pacific 

 Northwest have shown that breeding birds select stands 

 of old-growth forest or stands that provide platforms for 

 nests and suitable protection from predators in California 

 (Paton and Ralph 1988), Oregon (Grenier and Nelson, this 

 volume), and Washington (Hamer and Cummins 1990, 1991). 

 All murrelet nests found in these states have been located in 

 old-growth conifer forests (Hamer and Nelson, this volume 

 b). Whereas nesting habitat requirements of murrelets at the 

 individual tree or nest platform and the stand level have been 

 examined in some detail, characteristics of murrelet nesting 

 habitat at the landscape level are less understood (Hamer 

 and Cummins 1990). 



Recently-completed studies by Hamer and others (1993) 

 have provided much needed information on suitable nesting 

 habitat characteristics within forest stands in Washington 

 that can be used as predictors of murrelet occupancy from 

 ground-based surveys or forest inventories. No studies have 



1 Chief Research Wildlife Biologist, Pacific Northwest Research 

 Station, USDA Forest Service, 3625 93rd Ave., Olympia, WA 98512-9193 



2 Geographer, Pacific Northwest Research Station, USDA Forest 

 Service, 3625 93rd Ave., Olympia, WA 98512-9193 



3 Program Analyst, Pacific Northwest Research Station, USDA Forest 

 Service, 3625 93rd Ave., Olympia, WA 98512-9193 



as yet considered whether landscape-level characteristics of 

 nesting habitat such as shape, size, or configuration among 

 forest stands have predictive capabilities for occupancy by 

 murrelets. To determine if broad-scale patterns of habitat 

 distribution influence murrelet occupancy, we initiated a study 

 of relationships between amount and configuration of habitat 

 and occupancy of murrelets at previously surveyed locations. 

 Information on relationships between habitat characteristics 

 and occupancy by murrelets at broader scales could be of 

 value in planning conservation strategies and guidelines for 

 management at the regional level. Assessments of habitat 

 requirements across all scales nest, stand, site, and landscape 

 are necessary to determine the proper mix of management 

 guidelines to assure adequate amounts and configuration of 

 nesting habitat for the murrelet in the Pacific Northwest. 



Methods 



Analysis of landscape attributes of Marbled Murrelet 

 habitat selection proceeded at two scales. A broad scale 

 analysis within major river basins considered the distribution 

 of potential habitat among land owners (Federal and non- 

 Federal) over the species' range in Washington. A more site- 

 specific analysis considered the influence of landscape 

 characteristics immediately adjacent to survey sites on 

 occupancy status of murrelets. We generated statistical 

 measures for both scales of analysis using Geographic 

 Information Systems (GIS) and landscape pattern programs. 



Data Sources 



We obtained a database of all murrelet survey locations 

 (through 1992) from the Washington Department of Fish 

 and Wildlife (WDFW). This database was used previously 

 in regional conservation planning efforts for the Northern 

 Spotted Owl, Marbled Murrelet, and other species associated 

 with late-successional forests (Thomas and Raphael 1993). 

 Murrelet survey locations (n = 708) are represented by x,y 

 coordinate locations and associated attributes mapped in 

 GIS form (fig. 1). Survey points were coded by the WDFW 

 into five levels of murrelet detection (table 1) following 

 protocols and definitions of the Pacific Seabird Group (Ralph 

 and others 1993). Many of the locations were collected 

 before the currently accepted survey protocol was developed. 

 In addition, some of the database records represent multiple 

 sites clustered around a single survey station. For purposes 

 of this analysis, we analyzed only those surveys conducted 

 following protocol standards, and we eliminated any additional 

 multiple sites around a single station. The number of resulting 

 sites were n = 261. 



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



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