LANDSCAPE FUEL REDUCTION, FOREST FIRE, AND BIOPHYSICAL LINKAGES TO LOCAL HABITAT USE AND LOCAL EXTINCTION OF FISHERS (PEKANIA PENNANTI) IN THE SOUTHERN SIERRA NEVADA

Rick A. Sweitzer; The Great Basin Institute; sweitzerrick@gmail.com; Brett J. Furnas, Reginald H. Barrett, Kathryn L. Purcell, Craig M. Thompson

Fire suppression contributed to major changes in California's Sierra Nevada forests. Landscape fuel treatments are being used to reduce wildfire intensity and spread, but may negatively impact fishers. We used cameras to survey for fishers among 1-km2 grid cells in the Sierra National Forest, and applied occupancy modeling to evaluate responses of fishers to disturbance from forest fuel reduction. We detected fishers most often between 1380 m and 1970 m elevation, and detection probability occupancy was higher in habitats with high canopy cover. Local habitat use trended downward among cells with higher levels of managed burning+forest fires 25 years before surveys, and in cells where disturbance from restorative fuel reduction was higher. Local extinction increased with higher levels of restorative fuel reduction, but was not diminished by prior burning, or extractive activities. A trend for lower fisher occupancy in extensively burned grids suggested that wildfires did not decimate suitable fisher habitat. Wildfires increased in our study area after the 1980s, and may impinge on forests with higher fisher occupancy in the future. Forest fuel reduction imposes a more limited short term cost to fishers than previously believed, but less is known about the responses of denning fishers to management disturbance.

Ecology and Conservation of Mesocarnivores