The evidence seems unequivocal: The American pika is rapidly vanishing from the mountains of the western U.S., and scientists say it is climate change that has imperiled these tiny mammals.

Yet the Fish and Wildlife Service last month denied the pika protections under the Endangered Species Act, even though it has gone extinct locally in many areas of the West. Conservationists say politics rather than science drove the decision, which they called an enormous disappointment.

This is the second time the FWS has denied a request for pika protection. In 2010, it concluded that such efforts were not warranted . The species as a whole will be able to survive despite increased temperatures in a majority of its range and is not in danger of extinction in the foreseeable future, the agency said at the time.

That assertion came just a year after University of Colorado ecologist Chris Ray determined that the American pika would be extinct within the next 100 years if current trends continue.