Relationship of Marbled Murrelets with Habitat Characteristics at Inland Sites in California

We examined the range and the relationships of Marbled Murrelet (Brachyramphus marmoratus) behavior with habitat and landscape characteristics in isolated old-growth and residual forest stands from 2 to 400 ha in California. In large contiguous stands of old-growth forest in parks, we examined relationships of murrelet detections with elevation and topography. In isolated stands we found higher murrelet detection levels in stands with higher dominant and codominant crown cover and >50 percent coast redwood (Sequoia sempervirens). Surveys also were more likely to detect occupied behaviors at stands with higher crown cover and a greater proportion of redwoods. Density of old-growth cover and species composition may be the strongest predictors of murrelet presence and occupancy in California. Contrary to previous studies, we did not find that larger stands were more likely to have murrelets present. In the large park stands, we found that mean detection levels and the number of occupied stations were highest in the major drainages and at lower elevations. Major ridges tended to have lower detection levels and fewer occupied behavior stations. In recent years, much has been learned about the occurrence of Marbled Murrelets (Brachyramphus marmoratus) at inland forest sites. Throughout most of its range, the murrelet nests in old-growth forests within 50-75 miles of the coast (Carter and Morrison 1992). In California, Paton and Ralph (1990) conducted general surveys (Paton, this volume) to determine the distribution of murrelets in coastal old-growth and mature second-growth forests. Concentrations were found in regions containing large, contiguous, unharvested stands of old-growth redwood, mostly within state and federal parks, with the highest detection numbers in stands >250 ha. In excess of 200 detections for single-survey mornings have been recorded at some survey stations in remaining unharvested stands within parks in California, including Redwood National Park and Prairie Creek State Park in Humboldt County (Ralph and others 1990); and Big Basin State Park in San Mateo County (Suddjian, pers. comm.). Federal listing of the Marbled Murrelet as threatened (U.S. Fish and Wildlife Service 1992) has created a need for information about the role of habitat and landscape features for the murrelet. We conducted two studies to examine the relationships of the murrelet to habitat and landscape characteristics within old-growth forests, as defined by Franklin and others (1986). In isolated stands in fragmented landscapes (the Stand Study), we compared murrelet detections with stand size, structure,