Warming Climate of American West Pushes Pika to Extinction

SEATTLE, Washington, January 4, 2006 (ENS) - The American pika, a small mammal related to the rabbit, appears to be facing extinction in the Great Basin, new research has found.

The pikas, pronounced pie-cas, are sensitive to high temperatures, a characteristic that makes them an indicator species for global warming in the western United States where they live high in the mountains. Pikas live in rock-strewn talus slopes that provide them with relief from hot temperatures and protection from predators.

A University of Washington archaeologist who has examined fossil records covering the past 40,000 years says his work shows that the pikas are being pushed upward in their mountain habitat and are running out of places to live.

Archaeologist Donald Grayson says climate change and human activities appear to be the primary factors jeopardizing the pika, Ochotona princeps. Roads and livestock are encroaching on pika habitat, he says.

"Human influences have combined with factors such as climate change operating over longer time scales to produce the diminished distribution of pikas in the Great Basin today. This makes controlling our current impacts on them all that more important," said Grayson.

"Pikas are an iconic animal to people who like high elevations," he said. "They are part of the experience. What's happening to them is telling us something about the dramatic changes in climate happening in the Great Basin. Climate change will have a dramatic effect including important economic impacts, such as diminished water resources, on people."

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Pikas are being pushed ever higher into the mountains by human activities and climate change. (Photo courtesy Pika Works)
Pikas - also called rock rabbits, haymakers, conies, piping hares and whistling hares - are isolated in patches across mountainous areas in western North America, from the southern Sierra Nevada and Rocky mountains to central British Columbia in Canada.

In the Great Basin, which stretches from central Oregon south to Las Vegas, and from Reno in the west to Salt Lake City, these mountains are separated by large valleys with hot desert conditions that pikas cannot tolerate.

Grayson's analysis of 57 archaeological sites, published in the current issue of the "Journal of Biogeography," shows that pikas have been pushed to higher and higher elevations.

From 40,000 to about 7,500 years ago, populations of Great Basin pikas that are now extinct were found at an average elevation of 5,741 feet.

Seven of the 25 historically described populations of Great Basin pikas appear to have become extinct by the end of the 20th century.

The average minimum elevation of the 18 surviving Great Basin populations surveyed in 2003 by Erik Beever, now with the National Park Service, was 8,310 feet.

Grayson said new research, as yet unpublished, by Beever and by James Patton, of the University of California Berkeley Museum of Vertebrate Biology, shows the Great Basin picas are still retreating up the mountain slopes.

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Pika on a rocky talus slope in Wyoming (Photo courtesy Pika Works)
Beever has just discovered that two more pika populations in the Great Basin have gone extinct. In addition, the remaining picas have moved up in the mountains another 433 feet.

Patton, who has been studying wildlife in Yosemite National Park in the Sierra Nevada Mountains adjacent to the Great Basin, has reported a 1,700 foot upward increase in the range of pikas there over the past 90 years.

Found as low as 7,800 feet in 1910, picas now cannot be found below 9,500 feet in Yosemite National Park.

"We might be staring pika extinction in the Great Basin, maybe in Yosemite, too, right in the face. Today, the Great Basin pika is totally isolated on separated mountain ranges and there is no way one of these populations can get to another," said Grayson. "They don't have much up-slope habitat left."

There are 29 species of pikas in the world, most of them in Asia. During the ice ages, two species came across the Bering Strait. One settled in Alaska and the Canadian Rockies. The other traveled south to the Sierras and Rocky Mountains in the United States.

The animals are about the size and shape of a guinea pig, about eight inches in length and weigh about seven ounces. Their maximum life span is seven years. Preyed upon by eagles, hawks, bears and foxes, pikas' most dangerous predator is the ermine, which is capable of following a pika into its rocky tunnels.