Relationship of Marbled Murrelets with habitat characteristics at inland sites in California

Miller, Sherri; Ralph, C

Old-growth redwood forests were surveyed for breeding behavior of the rare Marbled Murrelet at Redwood National and State Parks, Humboldt Redwoods State Park, and Big Basin Redwoods State Park in California. 'Density of old-growth cover and species composition may be the strongest predictors of murrelet presence and occupancy in California.' Study sites included both smaller, isolated stands and large contiguous old-growth stands. Although this study found little difference between them in murrelet presence, the paper also says that '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.' An appendix describes methods. Includes 7 data tables. COMPLETE AUTHORS' ABSTRACT: "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 forests 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."