The pika is a small member of the rabbit family that lives throughout the northern hemisphere. It thrives in cool and rugged places, such as the rocky slopes of high alpine meadows. It's popular among hikers and animal lovers. But a growing body of research indicates that pikas may be one of the first animals in the American Mountain West to fall victim to global warming.

During the summer, pikas scamper across the talus - the stones and broken boulders on the mountain slopes - dining on flowers and grass, and calling to each other with their distinctive squeak. These hard-working creatures also gather grass to dry for winter food.

University of Colorado biologist Chris Ray, a world-renowned expert in pika biology, describes them as about as big as a potato. "And they look kind of like that from a distance," she adds.

Ray spends many hours each summer, sitting in the meadows watching them, and she's noticed something disturbing. Pikas in many parts of the mountain west are vanishing from the lower elevations of their habitat at a rate of 10 meters every year. Because mountains narrow to a point, that means with each passing year, there's less habitat left for the American pika. But there also seem to be fewer pikas.

Studies show a high mortality in pika colonies at lower elevations, and no one knows why. Ray and other researchers have found no disturbance of their rocky homes. No poisons have been sprayed. There's no obvious change in predators.

But there is a steady increase in the average alpine temperature. This has led many biologists to conclude that climate change is killing the pika. One reason is that the animals easily succumb to heat exhaustion. But Chris Ray says it's more than that. "There are just so many ways that global warming can affect a species, besides turning up the heat," she explains.

For example, warmer weather makes many diseases more contagious, and gradually causes a change in edible vegetation. And rising average temperatures thin the snow that used to cover this area throughout the bitter cold Rocky Mountain winter. In higher elevations, where the blanket of snow is still thick, pikas are insulated from the cold. But lower down a mountain, where the snow is thin, Ray suspects that pikas are freezing to death in their winter dens.

What's more, Ray worries that pikas may be the alpine equivalent of the canary in the coalmine, whose declining health is a signal of impending environmental danger. As time goes on, she suspects that additional studies will find many species are disappearing because of climate change, both in the United States and around the world.

Her colleague, Colorado naturalist Steve Jones, says it doesn't have to be that way. He points to several endangered species that increased their numbers because citizens and government agencies set aside protected habitats for them. "Bald eagle is one. Peregrine falcons. Big horn sheep were not here a century ago, and neither were elk."

But Jones admits that the pika's situation is more complex. "This is a perfect habitat here for pikas. This ecosystem, the alpine ecosystem, is largely intact. It has had very little disturbance," he says. "Pika are actually thriving here at higher elevations. The frustrating thing is that there's nothing we can do about global change in terms of protecting that ecosystem except to reverse that global change."

Chris Ray agrees. "We can't just fence off this talus and make it good for pikas. The changes happening here are more subtle than that, and they probably have to do with global warming."

But she insists it's not too late. "I'm really hoping that we'll sign on to the Kyoto agreement or more. I'm really hoping that we will embrace, for example, better, higher CAFE standards for automobiles. I hope we'll drive less, use more public transportation. I hope we'll stop building coal-fired power plants. There are many things we can do. I hope everybody will put solar panels on top of their homes. I don't see any other way to turn around what's happening to the pika and many other high-altitude species."

Otherwise, Chris Ray says, she's going to miss the pikas, and miss sharing them with her son, who's due in September. "I would certainly like him to be able to experience at least what I've experienced. I'd like to be able to share with him observations of pikas. And pikas are unfortunately disappearing from some of my favorite places. And I don't want that to be lost from him or for me. And at the rate that they're disappearing from some of these sites, it seems like they'll be gone within his lifetime."

Many wildlife preservation groups in the United States are using the pika's plight to urge citizens to push for solutions to global warming. Meanwhile, Ray continues her research of the vanishing pika, to document the impact of climate change.