West Coast Fisher Distribution Modeling Project

Fishers are a medium-sized carnivore of conservation concern in portions of their distribution. Fishers in the southern Sierra Nevada are federally threatened and other populations have been evaluated for federal listing on several occasions. Small and isolated populations are the most immediate and challenging threat to fisher persistence in Washington, Oregon and California.

Species distribution, habitat associations, and population size are critical information needs for species recovery. Fisher distribution patterns and habitat associations have been evaluated using presence-only and expert opinion models. These models frequently fail to meet assumptions (e.g., representative sampling, constant detection probabilities); increasing calls for analyses in detection-non detection frameworks.

We are modeling the distribution, habitat associations, and population sizes of fisher across Washington, Oregon, and California. We are developing a hierarchical model of detection-non detection data using occupancy and integrated modeling to estimate these important parameters. Our results will be a useful decision-support tool to promote species recovery in the face of stochastic events and a changing climate.