Chapter 6: Characteristics of Marbled Murrelet Nest Trees and Nesting Stands

Abstract

We summarize the characteristics of 61 tree nests and nesting stands of the Marbled Murrelet ( Brachyramphus marmoratus ) located from 1974 to 1993 in Alaska, British Columbia, Washington, Oregon, and California. Evidence of breeding 30-60 km inland was common in California, Oregon, and Washington. Nesting greater distances from the coast may have evolved to avoid nest predation by corvids and gulls which are more abundant in coastal areas. In California, Oregon, Washington, and British Columbia, murrelets nested in low elevation old-growth and mature coniferous forests, with multi-layered canopies (>2), a high composition of low elevation conifer trees ( x = 91 percent) and, on the lower two-thirds of forested slopes, with moderate gradients ( x = 23 percent slope). Stand canopy closure was often low ( x = 50 percent), suggesting use of canopy openings for access to nest platforms. Nests in the Pacific Northwest were typically in the largest diameter old-growth trees available in a stand ( x = 211 cm); many nest trees were in declining conditions and had multiple defects. It is likely that western hemlock and Sitka spruce constitute the most important nest trees, with Douglas-fir important south of British Columbia. Many processes contributed to creating the nest platforms observed. Mistletoe blooms, unusual limb deformations, decadence, and tree damage, commonly observed in old-growth and mature stands, all appear to create nest platforms. Therefore, the stand structure and the processes within a stand may be more important than tree size alone in producing nesting platforms and suitable habitat. Moss cover was also an important indicator of suitable nesting habitat.

Parent Publication

• Ecology and conservation of the Marbled Murrelet

Citation

Hamer, Thomas E.; Nelson, S. Kim. 1995. Chapter 6: Characteristics of Marbled Murrelet Nest Trees and Nesting Stands. 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. 69-82