FISHER OCCUPANCY TWENTY-FIVE YEARS AFTER TRANSLOCATION IN THE ROCKY MOUNTAINS OF MONTANA

Abstract

The historical distribution of Fishers throughout Montana and the northern Rocky Mountains of the United States is poorly understood, and most Fishers in Montana appear to be descendants of translocated animals originating from the midwestern United States and British Columbia; however, a genotype that is unique and native to the Northern Rockies of Idaho and Montana exists in west-central Montana. Predictions based on Idaho models depict potential suitable habitat for Fishers throughout the Cabinet Mountains of northwestern Montana, yet distribution, occupancy, and population status is currently unknown for these Fishers. We conducted the 1st comprehensive monitoring of Fishers in the Cabinet Mountains of Montana using baited camera/DNA stations. We detected Fishers at 7 out of 21 cells, which resulted in a 0.43 probability that Fishers occupied a grid cell. Detection probability was low. Genetic analysis revealed a minimum population count of at least 4 individual Fishers in the study area, but all individuals successfully identified were males and of midwestern genetic origin. The low number of Fisher detections may indeed reflect low abundance of Fisher. We recommend future multi-season monitoring over a longer period to increase precision of occupancy estimates, and additional research is needed to evaluate the lack of female detections. We also recommend maintaining a closed trapping season on Fishers, until data exist to document a population large enough to sustain harvest.