Warming May Be Taking Toll on Pikas, Study Reveals
RENO, Nev. Populations of the American pika -- a hamster-like rodent unable to survive in warm climates -- continue to decline in the West, apparently due in part to global warming, a new study says.
Local populations of pikas have gone extinct at more than one-third of 25 sites surveyed since the mid-1990s in the Great Basin region between the Sierra Nevada and Rocky Mountains, according to the study conducted by a researcher for the U.S. Geological Survey and funded by the World Wildlife Fund.
"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.
Pikas, a relative of the rabbit with small, round ears, are known for their high-pitched whistle often heard when humans approach. They gather wild flowers for food and make their homes among broken rocks at high elevations of mountain ranges in the western United States and southwest Canada.
Beever published a study in the Journal of Mammalogy in February 2003 that found populations of pikas had disappeared at seven of the 25 sites where he had documented them in the mid- to late-1990s in California, Oregon and Nevada.
Results of a follow-up field study this summer 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 told The Associated Press.
"At the places where they have been lost, the sites were hotter and drier than sites where they have remained," he said in a telephone interview.
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 cool as 77 degrees, he said.
Beever, who did his graduate work at the University of Nevada, Reno, now works out of the USGS Forest and Rangeland Ecosystem Science Center in Corvallis, Ore. His previous research 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 shows the importance of efforts to combatting 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.
"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."
Critics say they don't believe humans have anything to do with the gradual warming of the Earth.
"The whole idea that global warming causes extinctions is really quite nonsensical," said Robert Ferguson, executive director of the Washington-D.C.-based Center for Science & Public Policy, affiliated with Frontiers of Freedom, a think tank created by former Sen. Malcolm Wallop, R-Wyo.
"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.
"The `Dust Bowl' in the American West and Southwest exceeded things we have today for a very very long time. So if warming affects them, these (pikas) should all be extinct already," he said.
Beever said most alpine animals are expected to adapt to rising temperatures by seeking higher elevations or migrating farther north.
But the pikas live essentially on high-elevation "islands" and face great risks when attempting to migrate across lower elevation valleys. One-half mile is a long distance for a pika to travel in a lifetime, he said.
The loss of local populations of pikas is especially troubling because most local extinctions of animals are driven by loss of habitat, Beever said.
"We've had no change in habitat and yet we are seeing all these losses of pikas," he said.
He said he's now documented five different mountain ranges across the Great Basin where historic populations have been lost at the lower elevations, but remain in the same ranges at higher elevations.
Those that have gone extinct the past decade, Beever said, include sites in southeast Oregon in the Steens and Warner mountain ranges, sites in northwest Nevada near Summit Lake south of the Sheldon National Wildlife Refuge and in the Pine Forest mountain range south of Denio, and sites in central Nevada in the Desatoya range west of Austin.
Beever said he returns at least twice to confirm a population is missing at spots he documented them before. The pikas signal call makes their presence easier to determine than with many animals, he said.
"One of the nice things about pikas," he said, "if they are there, you'll know it."
Source: Associated Press