Grand Teton National Park Researchers Keeping an Eye on Pikas
Climate-driven change in mountain ecosystems is readily visible across the National Park System. Regardless of whether you believe humans are contributing to the change, it's under way. In Glacier National Park the rivers of ice are shrinking, in Rocky Mountain National Park bark beetles are ravaging forests, and in Yellowstone National Park atypically warm stream waters in summer are stressing fish.
To better gauge the climate's impact on pikas in their park, Grand Teton National Park biologists are working to establish baseline data for these tiny creatures. This past summer park biologists teamed up with colleagues from Yellowstone and the Teton Science Schools to survey pika habitat in the park.
The American Pika lives at high elevations and although they are found throughout the Teton Range, little is known about their habitat requirements, distribution, and historic or current range, according to Grand Teton officials. They note that recent scientific studies suggest that the 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.
For instance, in a study conducted in Nevada’s Great Basin by Eric Beever, an ecologist with the U.S. Geological Survey, seven 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 might eventually reach an elevation limit in their response to increasing temperatures.
Additionally, habitat models recently developed by April Craighead, with Craighead Environmental Research Institute, and Scott Loarie, with the Carnegie Institute, predict that pikas could disappear from more than 80 percent 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 might 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. While a decision has yet to be issued, 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, Grand Teton officials said.
This past summer Grand Teton biologists used a geographic information system to model 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, the park reported.
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.
According to Grand Teton officials, this project serves as a critical first step in documenting where pika populations exist and ultimately will help biologists understand how those populations might 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.