Warming may be taking toll on pikas

RENO, Nev. – Populations of the hamster-like American pika continue to decline in the West and global warming is partly to blame, a new study says.

Local populations have gone extinct at more than one-third of sites surveyed since the mid-1990s, according to a study by a researcher for the U.S. Geological Survey and funded by the World Wildlife Fund.

The sites are located in the Great Basin region between the Sierra Nevada and Rocky Mountains.

Pikas, relatives of the rabbit with small round ears, are known for their high-pitched whistle. They gather wildflowers for food and make their homes among broken rocks at high elevations of mountain ranges in the western United States and southwest Canada. They are unable to survive in warm climates.

“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 eco-region,” said Erik Beever, a USGS ecologist.

In February 2003, Beever published a study in the Journal of Mammalogy that found populations of pikas had disappeared at seven of the 25 sites where he documented them in the mid- to late-1990s in California, Oregon and Nevada.

This summer, results from a follow-up field study showed extinctions at two more of seven resurveyed sites, for a total of nine sites where they no longer exist, or 36 percent, Beever said.

He said he intends to publish details of those findings after he completes another round of surveys next summer.

“There are several contributing factors, but climate seems to be a very strong factor,” Beever said. “At the places where they have been lost, the sites were hotter and drier than sites where they have remained.”

Previous research suggests American pikas are vulnerable to global warming because they live in areas with cool, relatively moist climates, Beever said. They’ve been shown to be unable to survive just six hours in temperatures as warm as 77 degrees.

Previous research by Beever, who works out of the USGS Forest and Rangeland Ecosystem Science Center in Corvallis, Ore., has suggested climate change may be interacting with other factors, such as increased road building and smaller habitat areas, to increase extinction risks.

Brooks Yeager, vice president in charge of global threats at the World Wildlife Fund in Washington, D.C., said the new data show the importance of efforts to combat global warming by reducing heat-trapping emissions from the burning of fossil fuels.

“Extinction of a species, even on a local scale, is a red flag that cannot be ignored,” Yeager said.

Critics say they don’t believe global warming is the cause of extinctions.

“The whole idea that global warming causes extinctions is really quite nonsensical,” said Robert Ferguson, executive director of the Center for Science & Public Policy based in Washington, D.C.

“Species go extinct for an awful lot of reasons. We’ve had periods in the past where temperatures were higher than they are today,” Ferguson said.