The American pika isn't heading for the endangered species list, but federal scientists said there's no question it bears watching as the West warms in the coming decades.

The U.S. Fish and Wildlife Service formally announced its decision Friday that Endangered Species Act protections aren't warranted for the climate-sensitive pika, a mountain-dwelling relative of the rabbit that lives in 10 Western states.

Agency officials acknowledge, though, that there's still plenty that's not known about the pika, a species that can be difficult to study because of its remote mountain habitat.

Environmentalists - disappointed by the decision made public a day earlier - had sought federal protections for the pika because of threats from global warming. Pikas are sensitive to temperatures and, as conditions warm, they have moved up-slope and, in some cases, run out of cool refuges.

John Isanhart, a biologist with the Fish and Wildlife Service, said Friday that while lower-elevation pikas might disappear as the West warms, enough pikas at higher elevations across the West should survive to keep the species from going extinct.

Officials said they expect most pikas in the Rocky Mountains and along the West Coast will survive in warmer conditions, while in the Great Basin around Nevada, which has already seen some the disappearance of some local populations, pikas face a tougher struggle.

Harder still is predicting how climate change will affect total population figures.

"It's pretty difficult to look into a crystal ball to look where a species is going to be in the next 40 years," said Isanhart, who helped review the pikas' status across the West over the last year.

What is known is that temperatures will almost certainly continue to rise across nearly all pika habitat in the coming years, scientists predict.

Of 22 pika sites analyzed across the West, federal officials expect that about half will see high enough summer temperatures that put local pikas at risk. But, Isanhart said, each site includes pikas that live at high and low elevations and that, in most cases, it'll just be the low-elevation pikas that are endangered.

A better gauge of pika survival is likely the temperature in the below-surface rocks and crevices where pikas seek refuge. Some work has been done to analyze temperature trends in those areas but more research is needed, agency officials said.

Part of the complexity with predicting the fate of the pika is that they appear across such a vast area.

Pikas are found at progressively higher locations - where temperatures are cooler - as you move south. In Canada, for instance, they can exist from sea level up to 9,800 feet. Farther south, they're rarely seen below 8,000 feet, federal officials said.

In the coming years, officials expect to see intensified interest in how local pika populations respond to warming temperatures. The science to this point is far from robust, federal officials said.

Still, "the law says you make the decision based on the best available information," said Michael Thabault, an assistant regional director for the agency.

If new research indicates pikas are losing the struggle against climate change, agency officials said Friday they'll re-examine whether they need federal protections.