Chapter 17: Inland Habitat Associations of Marbled Murrelets in Western Washington

Abstract

Little research has been done to quantify and describe the structural characteristics of forest stands that are associated with Marbled Murrelet (Brachyramphus marmoratus) nesting in the Pacific Northwest. Vegetation measurements and murrelet surveys to determine occupancy were conducted in stands located throughout western Washington. I used logistic regression to contrast stand attributes between occupied (n = 64) and unoccupied (n = 87) stands. The probability of occupancy of an old-growth stand increased with increasing total number of potential nest platforms, percent moss coverage on the limbs of dominant trees (≥81 cm d.b.h.), percent slope, the stem density of dominant trees, and the mean d.b.h. of western hemlock. The probability of occupancy of a stand decreased as lichen coverage on the limbs of dominant trees, stand elevation, and canopy closure increased. Mean detection rates and the percent of stands surveyed and verified as occupied declined sharply with an increase in elevation over 1,067 m, and for stands >63 km from salt water. The relationship of the number of potential nest platforms and elevation to the probability of occupancy was best explained by comparing the structural characteristics of old-growth trees for the five conifer species available for nesting. Land management activities that reduce or affect the number of potential nest platforms/ha, composition of low elevation conifers, moss cover on tree limbs, stem density of dominant trees (≥81 cm d.b.h.), or canopy closure, would reduce the quality of a site as nesting habitat for murrelets. Reproductive success should be used as a measure of habitat suitability in future studies by intensively studying occupied stands that have high detection rates of Marbled Murrelets and locating a sample of active nests to observe.

Parent Publication

• Ecology and conservation of the Marbled Murrelet

Citation

Hamer, Thomas E. 1995. Chapter 17: Inland Habitat Associations of Marbled Murrelets in Western Washington. In: Ralph, C. John; Hunt, George L., Jr.; Raphael, Martin G.; Piatt, John F., Technical Editors. 1995. Ecology and conservation of the Marbled Murrelet. Gen. Tech. Rep. PSW-GTR-152. Albany, CA: Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture; p. 163-176