Pushed by warmer weather higher into the Rocky Mountains, the pika, a rodent that grows to between 6 and 8 inches long, is losing its habitat at an increased rate, the Denver Post reported Monday.

"They've been driven upslope a half mile since the end of the last ice age," said Donald Grayson, an archaeologist and paleontologist with the University of Washington who has documented the presence of pika over the past 40,000 years.

"Pikas in general are now found at such high elevations that there's not a lot of places left for them," Grayson said.

Conservationists are now trying to procure endangered-species protection for the tiny critters, demanding that federal officials target global warming as a threat to their existence.

The center is suing the U.S. Fish and Wildlife Service to list the pika along with the polar bear and the ribbon seal as imperiled by global warming.