Presentation Abstract

Title: Investigating American pika habitat selection in the southern Greater Yellowstone Ecosystem
Session Title: "Biology, management, & conservation of Pikas & Other Montane Animals"
Session Number: 50
Session Time: Tuesday, Oct 16, 2012, 8:30 AM -10:10 AM
Presentation Time: Tuesday, Oct 16, 2012, 8:50 AM - 9:10 AM
Author(s): Embere Hall1, Annie Loosen1, Erik Beever2, Kerry Murphy3, Leah Yandow4, Laura Oles5, 1Conservation Research Center of Teton Science Schools, Jackson, WY, 2Northern Rocky Mountain Science Center, USGS, Bozeman, MT, 3Bridger-Teton National Forest, USFS, Jackson, WY, 4Wyoming Cooperative Fish and Wildlife Research Unit, University of Wyoming, Laramie, WY, 5Bridger-Teton National Forest, USFS, Kemmerer, WY, Contact: embere.hall@tetonscience.org
Abstract Body: Contemporary climate change has altered classic extinction dynamics. Consequently, conservation in alpine ecosystems must consider habitat selection patterns under novel conditions. American pikas (Ochotona princeps) and are an ideal species for evaluating climate-driven changes in habitat selection because of their temperature sensitivity, dependence on snow and naturally patchy distribution.
Relatively little is known about pika distribution or habitat selection in the Greater Yellowstone Ecosystem, despite range-wide research initiatives. As a result, regional responses to climate change are largely speculative. To better assess pika habitat selection, we examined pika occupancy at 211 sites on the Bridger-Teton National Forest, June -October 2010 and 2011. We generated sample points in four elevation bands using a generalized random tessellation stratified (GRTS) sampling design. At each site we surveyed for pikas in a 12m fixed-radius plot and used a 100m line-point intercept transect to quantify forage. We deployed 40 pairs of surface/subsurface temperature loggers at a subset of points to better understand the relationship between ambient and subterranean temperatures.
Forty-eight percent of sites were occupied within the 12m plots. Occupancy rates were higher with increased detection distance from plot center (0-200m, 67% occupancy). We used logistic regression models and AIC model selection to examine predictors of patch occupancy. Important predictors included elevation, forage availability and rock size. Low elevation loggers recorded temperatures below -10°C during 10.6% of 9,138 hours. In contrast, medium and high elevation temperatures were below -10°C during 2.1% and 2.7% of hours, respectively. We recorded no hours in which temperatures exceeded 28°C, a proposed limiting heat threshold. Results of our work indicate that cold exposure and snow cover may be drivers of pika habitat selection. With continued temperature increases and low elevation snow depths predicted near zero by the end of the century, pikas and other alpine mammals will face increasing difficulty.



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