Some mountain animals, left with smaller ranges to forage for food, face extinction while others are competing with animal populations in new habitats, Science reported.

"These kinds of changes have been going on forever," said James Patton, a biologist at the University of California, Berkeley, Museum of Vertebrate Zoology.

"The only difference is ... the speed with which these changes are taking place," Patton told the San Francisco Chronicle.

Patton and colleagues surveyed 28 mammal species studied by late Berkeley ornithologist Joseph Grinnell beginning in 1914.

They found that since Grinnell completed his work, the central Sierra National Forest in California had seen continuous warming, with nighttime low temperatures averaging 5 degrees Fahrenheit higher than 90 years ago.

During the same period, more than half the species Grinnell studied shifted their ranges upward by as much as 1,600 feet, the researchers said.

Others that stayed put, such as the bushy-tailed wood rat and Allen's chipmunk, significantly shrank in number and face extinction, the researchers said.

Similar changes endanger plant and insect species in some of Earth's warmest places, a companion report by University of Connecticut entomologist Robert Colwell said.