Northern Sierra Fisher Reintroduction Project

Understanding if fishers can persist in forests that are managed for timber production is an important area of research. Evaluations of fisher population viability on managed landscapes, however, have received surprisingly little attention, even though they may play an important role in fisher recovery. Forests in the western United States available for fisher recolonization include extensive landscapes managed for timber production. Though fishers can occupy and reproduce in these forests, large-scale harvest of late-successional forests were also some of the primary causes for fisher population decreases across North America. Thus, understanding whether fisher populations can persist in systems used for timber production is imperative to their conservation.

We used a reintroduction of fishers to a privately-owned forest managed for timber production in northern California to experimentally evaluate the viability of a fisher population on a landscape managed for timber production. We studied this reintroduced population of fishers for 8 years using annual live-captures and year-round tracking with radio telemetry. Using population modeling with spatial capture-recapture methods, we estimated this population of fishers to be growing during the study period. The density of the reintroduced fisher population in 2017 (10.8 fishers/100 km2) was within the reported range of fisher densities across the western United States. The reintroduction of fishers to previously occupied portions of their range is an important component of fisher conservation and will play a role in the recovery of the species in western portions of the fisher’s range. Our results suggest that forests managed for timber production with landscape conditions similar to our study area may be important for future fisher reintroductions and species recovery (Green et al. 2022).