The cheerful chirping of the pika can be heard in rocky terrain at high elevations. Sadly, rising temperatures have diminished the habitat for the cold-loving pikas, who can perish from overheating. A recent study found that pikas had vanished over a 10-year period from 7 of the 25 sites surveyed in Nevada, California and Oregon.

More information about pikas and climate change.

"Pikas may unfortunately be the 'canary in the coal mine' when it comes to the response of alpine and mountain systems to global warming. Their disappearance is an indication that our heavy reliance on polluting fossil fuels is causing irreparable damage to our environment." Dr. Lara Hansen, Senior Scientist, World Wildlife Fund

A tiny insect has become a serious threat to the mighty grizzly bear. As a result of warming temperatures at high elevations, the mountain pine beetle has gained a foothold in whitebark pine forests. This has resulted in widespread destruction of the trees, which provide an important staple in the grizzly's diet.

More information about grizzly bears and climate change.

"If these trees go, they could take Yellowstone's grizzlies..with them. If we want to save not just the whitebark pine, but the animals and plants like the grizzly bear that depend on this tree for food, we need to move to protect them now." Louisa Wilcox, NRDC Wildlife Advocate

Climate change and other environmental ills have put over a third of the world's amphibian species on the brink of extinction. In Yellowstone, three of its four species are dwindling in numbers. In Yosemite and the Sierra Nevada, some populations of the yellow-legged frog have been reduced by over 90 percent.

More information about frogs and climate change.

"There's no question that we are in a mass extinction spasm right now. Amphibians have been around for 250 million years. they made it through when the dinosaurs didn't. The fact that they're cutting out now should be a lesson for us." David Wake, Professor of Integrative Biology, UC Berkeley

Bighorn sheep survive in some of the most rugged areas in the country. In the Southwest, the trend toward higher temperatures and lower precipitation could jeopardize the animal's future. Over the last 65 years, 30 of the 80 separate populations in California have disappeared. In the Rocky Mountains, forests moving upslope may further threaten the bighorn's habitat.

More information about bighorn sheep and climate change.

"The harsh environment inhabited by desert bighorn sheep already has them walking on a knife's edge. It doesn't take too much to push them off. The bottom line is that more than one-third of the populations that were once known are gone." Clinton W. Epps, PhD, Assistant Professor, Oregon State University.