Route to Extinction Goes up Mountains, Scientists Say

Voted the second cutest animal in North America in a recent World Wildlife Fund survey, the American pika is now climbing mountains toward extinction, say scientists.

Never heard of the American pika?

Not surprising, given where it lives -- often above the clouds in the upper slopes of mountain ranges across western North America, from New Mexico all the way into British Columbia.

The pika is the tiniest member of the rabbit family; it is the size of a tennis ball. Its young are the size of a fat walnut.

The American pika likes it chilly -- in fact, needs it chilly, as it sports a thick fur coat it does not shed in summer. Scientists have documented that pikas can die in under an hour if temperatures reach much above 75 degrees. Trouble is, warmer temperatures have been creeping steadily higher at all elevations due to man-made global warming, experts say. Unfortunately for pikas, the temperature increases are often most pronounced at the higher elevations that they usually inhabit.

And scientists are finding more and more pika colonies empty. "There are many places, where pikas used to be, where they're completely gone now," scientist Chris Ray of the University of Colorado told ABC News.

Clambering through a pika-less stretch of "talus" -- fields of rock fragments fallen from the peaks above where pikas hide from predators and the hot midday sun -- Ray told us how these "local extinctions" point to global warming. "They're going extinct from many of the lower elevations," Ray said. "If the current trends continue at the rate they're going right now, it's very likely that pikas will be extinct within the next 100 years."

Victims of Cold, Ironically Linked to Global Warming

For the American pika, life was already hard enough. It spends a lot of time scampering fast to escape the leaping mountain weasel, its chief enemy.

Weasels like to eat pikas. The weasel's pliable tube-like body -- with sleek tawny-and-white pelts beautiful to humans but terrifying to pikas -- can follow them through the crevices under the talus that frustrate the hawks and eagles.

Birds of prey also pick off the occasional pika unlucky enough to be caught in the open.

That's not the only reason they scamper with such speed, like cartoon minibunnies on fast forward, zigzagging between miniboulders.

They also race to collect enough flowers, leaves and grass in the short mountain summers to store up hay piles that they feed on all winter under the snow.

That snow helps keep pikas warm enough to survive the occasional below-zero cold snaps of winter -- like the Inuit in their igloos.

Ironically, such cold snaps may be another way global warming is killing pikas, say scientists.

"There's less snow cover now, due to global warming," biologist Ray told us. "A number of the empty colonies we're discovering in spring have hay piles only half-eaten. "

Andrew Smith of of Arizona State University - who began tracking the impact of warming on pikas decades ago - confirmed for ABC News that, in addition to direct overheating effects, there's evidence from various studies that pikas may also be dying during the winters due to lack of snow cover, and that "the winters -- especially at those lower elevation colonies -- are often seeing less snow now because of global warming."

Falling Off the Tops of Mountains

Longtime pika scientist Erik Beever reports that of 25 well-documented sites he has studied in the Great Basin (the area between the Rockies and the California-Oregon ranges) he now finds eight of them empty.

"The pikas are completely gone from a third of their sites, " Beever told us. "It's clearly related to global warming," he said, because thermal influences appear to be the most important driver of pika losses. However, Beever also said it is also clear that those temperature influences are combining with other factors-- such as the extent of rocky habitat and land use factors such as roads-- to affect populations across the Basin.

"Pikas are poor dispersers -- they can't just race over and recolonize an old site from another mountain," Beever explained.

"It's almost always too hot down in the valleys they'd have to cross," he said. "They'd run into uncrossable highways that weren't there when the last ice age ended. And they'd have to be out in the open, so they'd be in great danger of getting picked off by hawks."

So, with temperatures rising, the only way pikas have to go is up, chased by the steadily climbing warmer air that climate change is bringing -- and will continue to bring -- for at least the next 50 years, scientists say.

And when that heat reaches the top of a peak, that mountain's pikas are finished.

"Falling off the tops of mountains," as field biologists put it.

Same Pattern Found Around the World

Hundreds of studies report a growing number of species of plants and animals migrating further up slope, looking for cooler ground and, when there's no more to go, disappearing altogether.

In one extensive study of the California Sierra Nevada Mountains, researchers found many species have moved more than 2,000 feet up slope from traditional sites.

Studies are finding that global warming, as it scatters local ecosystems that evolved over eons, has countless ways to attack them -- not only the direct overheating effect of the rising temperatures.

Mountain frogs, for example, have been shown to be dying from a fungus that is made more lethal by warmer weather.

Ray said that in addition to the loss of winter snow cover and the risk of overheating in summer, she and her colleagues are also now considering whether a plague infection, already found in other animals and possibly spreading due to climate change, may also be attacking some pikas.

"Local pika extinctions are accelerating," said Ray.

With temperatures only expected to rise, the American pika is now looking out on a fast-changing world, and facing a problem bigger than weasels.

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