Climate change has animals heading for hills

Many small California mammals have shifted ranges to higher elevations

By Jeanna Bryner
Staff Writer
Updated: 11:45 a.m. ET Dec 14, 2006

SAN FRANCISCO - Chipmunks, mice and squirrels are heading for the hills, perhaps chased to higher elevations by a changing climate, scientists report.

Since the early 1900s, many small mammals in California have shifted their ranges dramatically, mostly to higher elevations.

Scientists compared modern notes with past museum director Joseph Grinnell, who investigated the diversity of mammals, reptiles, amphibians and birds along what he called the Yosemite Transect. With this information, scientists retraced this work, and documented with traps and photos the small mammals in this area that spans portions of the San Joaquin Valley, the Sierra Nevada, including parts of Yosemite National Park.

They incorporated the information into computer simulations of climate to see how the animals' ranges changed with climate changes.

"We can perhaps use this model to look into the future as long as the climate models are accurate," Chris Conroy of the Museum of Vertebrate Zoology said here this week at the annual fall meeting of the American Geophysical Union.

The pint-size pika, related to the rabbit, shifted its range to higher elevations. Known for its need for cold weather and snowfall, the pika is also on the move across western North America, according to past studies.

A few other furry mammals migrating:

The golden-mantled ground squirrel has shifted its primary habitat upward about 500 feet. The pinion mouse and pocket mouse now reside in the high-elevation Yosemite National Park — the first record of the mice there. The alpine chipmunk has scurried 1,800 feet upward since Grinnell's time.

The climate models are showing a relationship between the change in weather and the animal movement, the scientists report. To strengthen their story, Conroy said they'd like to incorporate biological information into the simulations, including an animal's diet, whether it hibernates, and how well it deals with cold weather.

To continue the project, they needed money. "So now that we have preliminary data, and we've shown that there are definite changes that we may be able to tie to climate change, that makes it much more reasonable to fund it," Conroy told LiveScience.

Recently, the National Science Foundation granted funding for the Grinnell Project. So the team will go out and collect data at high-elevation and mid-elevation sites, all of which extend beyond Yosemite.