"Population by population, we're witnessing some of the first contemporary examples of global warming apparently contributing to the local extinction of an American mammal at sites across an entire ecoregion," said Dr. Beever, an ecologist at the USGS and lead researcher.
In a follow-up field study to research published in the February 2003 Journal of Mammalogy, American pika (Ochotona princeps) populations were detected at only five out of seven re-surveyed sites that possessed pikas in Beever's research in the mid- to late-1990s. The original research documented local extinctions at seven of twenty-five sites in the Great Basin – the area between the Sierra Nevada and Rocky Mountains. The recent re-sampling brings the total number of sites at which American pika populations have suffered local extinction to nine out of twenty-five or 36 percent. Continued loss of populations raises concern, as does the fact that these results and other lines of evidence suggest that many of the losses have occurred towards the more recent end of the 14 to 91-year period since their scientific discovery.
"With clean energy solutions readily at hand, our leaders are responsible for either protecting or failing to protect our rich natural heritage from global warming," said Brooks Yeager, vice president, Global Threats, World Wildlife Fund. "Extinction of a species, even on a local scale, is a red flag that cannot be ignored--we must limit heat-trapping emissions from the burning of dirty fossil fuels for energy now."
Previous research results suggested that American pikas are particularly vulnerable to global warming because they reside in areas with cool, relatively moist climates and are unable to survive even six hours in temperatures as low as 77 degrees Fahrenheit when not allowed to behaviorally thermoregulate. As temperatures rise due to increasing emissions of CO2 and other heat-trapping gases, many alpine animals are predicted to seek higher elevations or migrate northward in an attempt to find suitable habitat. Living essentially on high-elevation islands and having limited dispersal capability means that American pikas in these regions have little option for refuge from the pressures of climate change because migration across low-elevation valleys represents an incalculably high risk for them – and perhaps an impossibility under current climatic conditions. Results from Dr. Beever's study published last year suggest that climate change may be interacting with other factors such as proximity to primary roads and smaller habitat area to increase extinction risk for pikas, creating detrimental synergistic effects.
A smaller relative of rabbits and hares, American pikas have short, round ears and usually make their homes among the broken rocks or talus at high elevations in the mountains of the western United States and southwestern Canada.
Hikers in the western mountains are perhaps most familiar with the call of the American pika, often heard when human visitors approach or travel on pika-occupied taluses. Some hikers are even lucky enough to catch a glimpse of them darting among the rocks or gathering alpine wildflowers and grasses for their winter food supply. American pikas may act as 'ecosystem engineers' at talus margins because of their extensive haying activities. Since food is difficult to obtain in winter in the alpine environment, pikas cut, sun-dry, and later store vegetation for winter use in characteristic 'haypiles' above a rock in talus areas.