Peak Performance

Not surprisingly, climate change has wiped out some ground squirrels at mountain sites in California. But thanks to human-occupied areas such as campgrounds, the animals have fared better than they might have otherwise, scientists say.

Mountain mammals face an especially tough challenge as the planet warms. They can’t move very far, and they may forage less in hot weather. More rain and flooding could be bad news for burrowers, while extreme winter storms may kill more animals.

Researchers investigated how Belding’s ground squirrels responded to climate change by re-surveying areas studied in 1902-1966. The team checked for the squirrels at 74 sites in the Sierra Nevada where the species had previously been found. The researchers also visited 47 other sites to see if the animals had moved to new locations.

The team found the squirrels at only 58 percent of the sites where the animals were seen in earlier surveys, according to the study in Proceedings of the Royal Society B. And the squirrels didn’t seem to have moved to new sites either. The changes were linked to warmer, wetter weather, suggesting that climate change was the culprit.

But campgrounds, farms, and other areas maintained by people appeared to give the squirrels a boost, perhaps because they provided more food and water. Without those sites, the species’ range would have retreated up the mountain by 255 meters, the team estimates. The researchers also found more squirrels in human-occupied places than undisturbed meadows.

The results suggest that landscapes altered by humans could actually offer “a potential protective effect,” the authors write. But that doesn’t mean we should start building condos on mountains. Urban development probably wouldn’t have the same benefit, the team says. Roberta Kwok | 17 August 2012

Source: Morelli, T.L. et al. 2012. Anthropogenic refugia ameliorate the severe climate-correlated decline of a montane mammal along its trailing edge. Proceedings of the Royal Society B doi: 10.1098/rspb.2012.1301.

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