Fisher ecology in the Sierra National Forest, California

Fishers (Martes pennanti) experienced population declines throughout their range during the twentieth century. In California there is a ∼400 km gap in their distribution, isolating fishers in the southern Sierra Nevada from populations in northern California. The fisher's conservation status in the southern Sierra Nevada is poorly understood, making management decisions about this species difficult. Fishers in this region are divided into at least 5 subpopulations separated by major river drainages. I compared two survey methods in the Kings River population to determine an effective strategy for monitoring fisher populations. I also used genetic data to explore the dispersal behavior of this species.; Using camera traps, I obtained estimates of demographic parameters for this population. Fishers in this region occur at lower densities than at other locations across their range, with only 10-11 animals/100 km2. Their annual adult survival rates (0.88) were comparable to those found in other studies, however there were wide confidence intervals around this estimate.; I used hair snares to perform a genetic tagging study on the same population. To complete this study, I developed 22 new microsatellite loci with samples from this population, northern California, Idaho, Minnesota, and Vermont. Only 6 of these loci were variable in the Kings River population, corroborating previous findings of the genetic isolation of fishers in the southern Sierra Nevada. I compared camera traps with hair snares for their efficacy in estimating population parameters. However, only 14 hair samples were identified as fisher hair, making estimation of demographic parameters using this method untenable.; I also used genetic methods to examine dispersal in this population. Based on the relationship between pairwise relatedness and geographic distance, I found that there was a slight difference between males and females in terms of their dispersal behavior. Overall, there was a decrease in pairwise relatedness at greater geographic distance. This relationship was slightly stronger in males than in females, suggesting greater male philopatry in this population. However, the strength of this relationship was not great. I recommend further studies of fishers, particularly at greater geographic scales, to more effectively address this question.