Distribution and status of the fisher (Martes pennanti) in Washington

Aubry, Keith; Houston, Douglas

We determined the current distribution of fishers (Martes pennanti) in Washington using sighting and trapping records, and evaluated their occurrence in relation to major vegetation and elevation zones. We obtained 137 records dating from 1894-1991. Martes pennanti still occurs in the Cascade Range and Olympic Mountains and in portions of the Okanogan Highlands, but is apparently very rare. We found no records from the eastern edge of Puget Sound, the Kitsap Peninsula, the southern Coast Range, or the Blue Mountains. Records of M. pennanti west of the Cascade crest were strongly skewed toward low to mid-elevations: 87% were at <1000m and the remainder were at <1800m. In contrast, only 30% of records east of the crest were at <1000 m, and 18% were from 1800-2200 m. These patterns may result from deeper, softer snowpacks at high elevations on the west side, which restrict the movements of M. pennanti in winter. Most western records (54%) were from the Western hemlock (Tsuga heterophylla) forest zone; remaining records were from the Pacific silver fir (Abies amabilis) zone (26%) and the Sitka spruce (Picea sitchensis) zone (20%). Most eastern records (53%) were from the Subalpine fir (Abies lasiocarpa) zone; others were from the Grand fir (Abies grandis)/Douglas-fir (Pseudotsuga menziesii) (37%) and Timberline/Alpine zones (10%). We predict that available habitat for fishers would be enhanced by minimizing forest fragmentation, maintaining high forest-floor structural diversity, preserving snags and live trees with dead tops, and protecting swamps and other forested wetlands.

Distribution and status of the fisher (Martes pennanti) in Washington

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