Global Warming Driving Pika Losses

By Cat Lazaroff

WASHINGTON, DC, February 25, 2003 (ENS) - The pika - a small mammal that makes its home on the talus slopes of western mountains in North America - may be one of the first animals to fall victim to global warming, new research suggests. A study published this month shows that global warming may have contributed to local extinctions of American pika populations in the Great Basin area, between the Sierra Nevada and Rocky Mountains.

A smaller relative of rabbits and hares, with shorter, rounded ears, American pikas can be heard calling back and forth with high pitched squeaks near the homes among broken rocks on high elevation slopes in the mountains of the western United States and southwestern Canada.

But new research published in the February 2003 issue of the "Journal of Mammalogy" indicates that pikas have already begun to vanish from these mountains.


The American pika, a smaller relative of rabbits and hares, may be North America's first mammalian victim of global warming. (Photo courtesy J. MacKenzie/ Newswire)
According to the new study, global warming appears to have contributed to local extinctions of American pika populations during the latter part of the 20th century. If the global warming trend is not reversed soon, through a major reduction in emissions of carbon dioxide (CO2) and other heat trapping gases, further population losses of the American pika may occur.

"Losses of pikas are disturbing because they are often assumed to be locally abundant and, in decades past, scientists assumed that alpine and subalpine ecosystems were relatively undisturbed because of their isolation," said Dr. Erik Beever, an ecologist with the U.S. Geological Survey's Forest and Rangeland Ecosystem Science Center, and primary author of the study.

"The responses of American pika populations are likely an early signal of the impacts of climate change in alpine and subalpine systems," Beever added.

The new study suggests that climate may be interacting with other factors such as proximity to roads, nearby livestock grazing and smaller habitat area to increase the extinction risk for pikas. The research represents one of few examples of field collected data on broad population losses of a mammal resulting at least in part from climate change.

Previous research results suggested that American pikas are particularly vulnerable to global warming because they reside in areas with cool, moist climates like those normally found in their mountaintop habitat. As temperatures rise due to increasing emissions of CO2 and other greenhouse gases, many native mountain animals are expected to seek higher elevations or migrate northward in an attempt to find suitable habitat.


Talus slopes like this one in Okanogan National Forest are typical habitat for the American pika. (Photo courtesy Pacific Biodiversity Institute)
Living essentially on isolated, high elevation islands 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 - and perhaps an impossibility under current climate regimes - for them.

If the pika vanishes, the loss of this species will impact other mountain residents in ways that are still unknown. American pikas are thought to act as 'ecosystem engineers' at the margins of talus slopes, because of their food gathering and storage activities.

As 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.

"American pikas may unfortunately be the 'canary in the coal mine' when it comes to the response of alpine and mountain systems to global warming," said Dr. Lara Hansen, a senior scientist at the World Wildlife Fund's climate change program. "Their disappearance is an indication that our heavy reliance on polluting fossil fuels is causing irreparable damage to our environment. We must make the switch to clean renewable energy resources like wind and solar now before it's too late."