Most bird species in Californiaâ€™s Sierra Nevadas have altered their ranges during the last century in response to changes in temperature and rainfall
Climate has become warmer and wetter in parts of the Sierra Nevada mountains over the past century, and the vast majority of the birds there have shifted their range accordingly, a new study suggests.
Over many generations, some plant and animal species can adapt to a slowly changing climate. When climate changes suddenly and dramatically, however, creatures generally shift their range, moving to new areas that offer suitable conditions, says Morgan Tingley, an ecologist at the University of California, Berkeley. Most previous studies have focused on speciesâ€™ responses only to temperature changes. But the new study by Tingley and his colleagues â€” reported online and in an upcoming Proceedings of the National Academy of Sciences â€” shows that birds respond to changes in precipitation as well.
The researchers tallied all the species of perching birds present during breeding season at 82 sites along four transects, which stretch from low foothill elevations up to Sierra peaks topping out at more than 3,600 meters (12,000 feet). Then, they compared the results of their field studies, conducted from 2003 through 2008, with results of similar surveys at the same sites conducted from 1911 through 1929. In the intervening decades, the average temperature at the sites has risen by about 0.8 degrees Celsius and average annual precipitation has risen almost 6 millimeters, says Tingley.