Outlook is grim for small rabbitlike mammals known as pikas

Wednesday, Jan. 4, 2006 | 8:12 a.m.

A tiny rabbit-like animal living in the mountains of Nevada appears on the brink of extinction, a new study shows.

Research published in the Journal of Biogeography on Friday indicates that the small mammals, called pikas, are being pushed from their mountainside habitat and are running out of space to live.

The pikas are sensitive to high temperatures. Climate change and human activities are the two major factors forcing the pikas to change their living quarters, University of Washington archaeologist Donald Grayson said.

The American pika is considered to be one of the best indicators of effects from global climate change.

Grayson's research spans a 40,000-year record of archaeological and paleontological sites combined with other unpublished work by several researchers.

The results paint a bleak future for the American pika (Ochotona princeps) in the Great Basin, including Nevada, eastern California and southern Oregon.

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

Human activities that appear to affect the animals include roads built near their habitat and pressure from grazing livestock.

The animals have been found from the southern Sierra Nevada and Rocky Mountains to central British Columbia.

In the Great Basin, mountain ranges are separated by large desert valleys with conditions that pikas can't tolerate, Grayson said. Pikas live in rock-strewn slopes that provide them with cooler air than that of deserts and with protection from predators.

Grayson analyzed 57 well-studied and dated archaeological sites, some dating as far back as 40,000 years.

Thousands of years ago, pikas lived at an average elevation of 5,741 feet. Of 18 surviving Great Basin populations surveyed in 2003 by Erik Beever, now with the National Park Service, the average height of pika habitat is 8,310 feet.

Seven of the 25 historically known populations of Great Basin pikas also appear to have become extinct by the end of the 20th century, Grayson said.

Mary Manning can be reached at 259-4065 or at manning@lasvegassun.com.