Chances are you probably will never see a polar bear in the wild as the poster animal for climate change disappears along with its Arctic habitat. But as you hike through the mountains of the American West, you can still catch a glimpse of another improbably cute critter threatened by climate change.

Not for long.

Like the polar bear, the American pika is losing its home as rising temperatures force the pint-size mammal farther up the alpine slopes of the Rocky Mountains and the Sierra Nevada. Resembling a rabbit but more adorable, the pika drops dead if its body temperature rises more than 3 degrees Celsius (5.4 degrees Fahrenheit). Now a new study confirms that pika populations are indeed vanishing as the West warms. Researchers found that the animal could become extinct across 88 percent of its range in California in the coming decades.

The findings could put new pressure on state and federal officials to protect the pika. After years of legal battles, the U.S. Fish and Wildlife Service and California wildlife officials denied petitions from conservationists to put the pika on state and federal endangered species lists. The reason: Despite several studies showing the pika’s distinctive high-pitched squeak is no longer heard at lower elevations, the government concluded it could survive rising temperatures.

But Joseph Stewart, the lead author of the study published in the Journal of Biogeography, said proof of the pika’s vulnerability to climate change has become irrefutable.

“The evidence that ongoing climate change is causing pikas to disappear from low elevation and warmer sites is solid,” Stewart, a graduate student in ecology and evolutionary biology at the University of California, Santa Cruz, wrote in an email. “The fate of the pika, and countless other species, will depend on how much global warming pollution we dump into the atmosphere.”

As pika populations fall, the entire food web will be altered. “Pikas are prey to many species and are also ecosystem engineers—affecting the composition of vegetation and soil nutrients,” Stewart said.

The study is the most extensive to date and compares historical records of sites occupied by pikas with detailed new surveys conducted by Stewart and his colleagues.

The pika’s peculiar physiology puts it at extreme risk from climate change. The animal, which lives on rocky alpine slopes, does not hibernate and thus must maintain a high internal temperature to survive frigid winters. In other words, it can’t turn off its heater, so during summers, it can die if temperatures rise too high.

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To keep cool, pikas spend most of their summer break under cool rock piles. But they must venture out to collect flowers and other vegetation they store to eat in the winter.

It’s a catch-22: If the summer is too hot, they risk death by leaving the safety of their rock piles, but if they don’t collect enough pika chow, they could starve during the winter. Also, climate change could cause pikas to freeze to death. That’s because they rely on the mountain snowpack to insulate their dens, and snow is increasingly disappearing from higher elevations as the climate warms.

Stewart and his colleagues found that pikas have vanished from 15 percent of the sites the animals historically had occupied in California. Moreover, the surviving pikas were living at elevations 1,640 feet higher, on average, than the extinct colonies.

The researchers concluded that pikas could disappear from 39 percent to 88 percent of their range in California by 2070, depending on how much greenhouse gas we continue to spew into the atmosphere.

Eventually, though, pikas will have nowhere to run.

“As climate change forces range contractions, species may effectively be ‘pushed off’ the tops of mountains by warming climate,” the study states. “That the American pika’s distribution is tied to mean summer temperature does not bode well for the future of the species.”