Date of Award:

5-2021

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Wildland Resources

Committee Chair(s)

Eric M. Gese

Committee

Eric M. Gese

Committee

James N. Long

Committee

Craig M. Thompson

Committee

Patricia A. Terletzky

Abstract

The fisher (Pekania pennanti) is a medium-sized carnivore found in mature forest stands across much of the northern United States. Although historically abundant in the west, fisher populations declined rapidly after fur trapping, extensive logging, and urban development reduced their numbers. Currently, biologists are concerned about the effects timber harvest practices have on fisher tolerance and adaptability when faced with changes to high-quality habitat stands. Tree removal and thinning of understory vegetation are frequently used to alleviate the spread of wildfires in previously dense forest stands with a potential for large-scale habitat loss; yet, a deficit of large trees and important vegetation attributes could be detrimental to fisher survival. We explored the impacts of timber treatments on fisher behavior and habitat preferences in a watershed system near Ashland, Oregon between 2010 and 2017. In our study, we assessed where fishers were found in their home ranges before and after treatments occurred (i.e., measuring fisher distance to treatment units), as well as the habitat features they selected pre- and post-treatment. Our results indicated that although most fishers moved away from treated areas, they still used untreated portions of their home ranges. For habitat selection, fishers chose sites at lower elevations, with low to moderate rugged topography, and they selected moderately steep slopes. They also preferred canopy cover 60% or higher and vegetation types consisting of conifers and hardwoods. We concluded that fishers were able to tolerate ongoing treatments in their home ranges as long as adequate canopy cover and large structures remained for their use on the landscape.

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