Modeling the effects of dispersal and patch size on predicted fisher (Pekania [Martes] pennanti) distribution in the U.S. Rocky Mountains

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Climate change impacts many species through shifts in habitat. The intensity of this impact will depend on the dispersal rates of the species, the patchiness of the environment, and the velocity of habitat change. Here the authors examine how dispersal affects projected future habitat availability for a threatened carnivore, the fisher (Pekania [Martes] pennanti). Non-invasive genetic sampling was used to detect fisher across their historical distribution in Montana and Idaho. This survey included 4846 non-invasive hair snares, of which 288 identified fishers through mitochondrial DNA analysis. The distribution of fisher across western Montana and northern Idaho was modeled using a suite of vegetative, topographic, and climatic variables. Future distribution was modeled using a global climate model and two climate change scenarios (high emissions [A2] or reduced emissions [B2]) and three time steps (2030, 2060, and 2090). The effects of dispersal ability and habitat patch size were incorporated into the model by varying the distance and enforcing a minimum patch size at which newly created habitat could be colonized. The probability of current fisher occurrence was found to be highest given the presence of mesic forest types with tall trees, high annual precipitation, and mid-range winter temperatures. Future predictions show an increase in area of high-probability habitat under most dispersal assumptions. Interestingly, a large contrast was found in results when minimum patch size and species dispersal capabilities were considered. The distribution model with full dispersal and no limits on patch size predicted a 24.5% increase in fisher habitat by 2090, whereas a dispersal limit of 1 km through non-habitat (agricultural fields and urban zones) and a minimum patch size yielded a loss of 25.8% of fisher habitat under this same scenario. Varying dispersal appears to limit habitat availability more than minimum patch size under most scenarios.

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ELECTRONIC FILE - Zoology: Mammals

SWAP (2/19/2016) citation:
Olson LE, Sauder JD, Albrecht NM, Vinkey RS, Cushman SA, Schwartz MK. 2014. Modeling the effects of dispersal and patch size on predicted fisher (Pekania [Martes] pennanti) distribution in the U.S. Rocky Mountains. [accessed 2015 Jun 1]; Biological Conservation. 169:89–98. http://www.fs.fed.us/rm/pubs_other/rmrs_2014_olson_l001.pdf