Effects of snow on fisher and marten distributions in Idaho

Abstract

Studies have suggested that deep snow may limit fisher (Martes pennanti) distribution, and that fisher populations may in turn limit marten (Martes americana) distribution. We tested these hypotheses in the Northern Rocky Mountains of Idaho, a region which differs from previous study areas in its climate and relative fisher and marten abundance, but in which very little is known about their distributions. We hypothesized that due to the assumed disparity in abundance between the sympatric members of the Martes genus (i.e., much greater marten abundance than fisher) fishers would not limit martens and their distributions would be indistinguishable based on snow attributes. We compiled data from multiple detection efforts conducted by various agencies where non-invasive hair-snaring devices were used to obtain DNA for species identifications of several mid-sized carnivores. We compared a suite of modeled snow attributes from fisher (n = 123) and marten (n = 173) detection sites and used logistic regression to combine our snow variables with habitat attributes at Martes detection sites. We found only minor differences in fisher and marten detection sites based on snow variables alone, and sites were indistinguishable based on combined climatic, vegetative, and topographic variables. However both species appeared to avoid the deepest snow zones. Our results support our hypothesis, suggesting that martens are more abundant than fishers in Idaho, and that snow attributes alone cannot be used to distinguish their distributions. Our research underscores the potential vulnerability of Idaho's fisher populations, and the importance of maintaining connectivity to known fisher population centers. Since both species appeared to avoid the deepest and softest snow, managers should consider snow attributes as well as vegetative and topographic factors when assessing habitat suitability for Martes. Furthermore, fisher reintroduction efforts may be more successful in areas with relatively low snow accumulations.

Citation

Albrecht, Nathan; Heusser, C.; Schwartz, M.; Sauder, J.; Vinkey, R. 2013. Effects of snow on fisher and marten distributions in Idaho. In: 43rd Annual Meeting of the Idaho Chapter of The Wildlife Society; 11-14 March 2013; Coeur d'Alene, Idaho. Idaho Chapter of The Wildlife Society. p. 20. Online: http://www.ictws.org/2013AnnualMeetingFinalProgram.pdf