Grand Teton National Park: Biologists Use GIS to Model Pika Habitat
In response to a growing body of evidence indicating that climate change is slowly and persistently affecting the ecology of plant and animal species on a global scale, Grand Teton National Park biologists – in collaboration with Yellowstone NP and Teton Science Schools – began a survey this past summer to develop baseline data on the local population of American pika (Ochotona princeps).
Pikas reside at high elevations (one of few mammal species to so) and although they are found throughout the Teton Range, little is known about their habitat requirements, distribution, and historic or current range.
Recent scientific studies suggest that the American pika, a small lagomorph found in subalpine and alpine talus slopes, can be used as an indicator species for evaluating the effects of climate change in western North America because of its sensitivity to temperature fluctuations.
In a study conducted in Nevada’s Great Basin by Eric Beever, ecologist with the U.S. Geological Survey, 7 out of 25 pika populations were lost in the 55-86 years since their last recorded presence. Researchers also found that pika populations shifted upward an average elevation of 500 feet in Yosemite National Park; a fact that suggests pikas may eventually reach an elevation limit in their response to increasing temperatures. In addition, habitat models recently developed by April Craighead, with Craighead Environmental Research Institute, and Scott Loarie, with the Carnegie Institute, predict that pikas may disappear from over 80% of their current range by the turn of the century. The majority of this disappearance is expected to occur in the pikas’ lower elevation range where temperatures may exceed thresholds for their survival.
Evidence linking changes in pika numbers and their distribution to a warming climate prompted the Center for Biological Diversity to petition the U.S. Fish and Wildlife Service in 2007 to list pikas under the Endangered Species Act (ESA). While a decision has not yet been issued on this petition, if listed, the American pika will become the first mammal species outside of Alaska to be protected under the ESA due to climate change threats.
Using geographic information system (GIS), Grand Teton biologists modeled suitable pika habitat located between Rendezvous Mountain and Paintbrush Canyon based on characteristics derived from published literature and related studies. Suitable habitat was defined as talus slopes less than 35 degrees in angle and no more than 400 meters from an established or “social” trail. Biologists selected 250 random locations to serve as established points for the survey. At each point, technicians assessed the area for habitat suitability and proceeded to locate physical evidence (scat, hay piles) as well as visual and/or vocal activity. Investigators then made population estimates in each plot and placed small sensors at ten survey sites that measure temperature several times a day. The sensors will be left in the field for one year, after which time they will be collected and the temperature data downloaded. Preliminary results from this year’s survey indicate that, within Grand Teton, observers found evidence of pika occupancy in or surrounding 47 of 49 plots, which ranged from 2000-3500 meters in elevation.
Grand Teton’s pika monitoring surveys were relatively simple and cost effective to implement. Based on this initial project, there is growing interest among Greater Yellowstone Ecosystem land management agencies in expanding surveys to include national forest areas, and other locations across the ecosystem.
This project serves as a critical first step in documenting where pika populations exist and ultimately will help biologists understand how those populations may change under different climate scenarios. Information from this project will be used to evaluate the health of Grand Teton’s pika population and comes at a time when pikas throughout the western United States are predicted to disappear in the near future due to climate change.
[Source: NPS press release]