How North American Mammals Respond to Climate Change

Climate change is impacting ecosystems across the globe. But how do different species respond to the shifting conditions? That's a good question, and one that scientists have now looked at more closely. They've examined North American mammal responses to human-caused climate change and have found which species are most vulnerable to shifting conditions.

In order to better assess mammals' response to climate change, the researchers examined more than 1,000 different scientific studies on mammal responses. Eventually, they selected 140 scientific papers containing population responses from 73 North American mammal species. The researchers then examined seven different responses to climate change by individual mammal species: local extinctions of species, range contractions, range shifts, changes in abundance, seasonal responses, body size and genetic diversity.

The researchers discovered that only 52 percent of the mammal species responded as expected to climate change. About 7 percent responded the opposite of expectations and the remaining 41 percent had no response. The two main traits that were linked to these responses seemed to be large mammal body size and restricted times during a 24-hour day when particular mammal species are active. In fact, almost all of the largest mammals responded negatively to climate change. In addition, mammals active only during the day or during the night were about twice as likely to respond to climate change as mammals that were more flexible in their activity times.

"Overall the study suggests our large, charismatic fauna--animals like foxes, elk reindeer and bighorn sheep--may be at more risk from climate change," said Christy McCain, one of the researchers, in a news release. "The thinking that all animals will respond similarly and uniformly to temperature change is clearly not the case."

That's not all the researchers found, either. They also discovered that species with higher latitudinal and elevation ranges--like polar bears--were more likely to respond to climate change than mammals living at lower elevations. In addition, the ability to hibernate, burro and nest was not a good predictor of whether or not a species responded to climate change.

"I think the most fascinating thing about our study is that there may be certain traits like body size and activity behaviors that allow some smaller mammals to expand the range of temperature and humidity available to them," said McCain in a news release. "These areas and conditions are not available to bigger mammals that live above the vegetation and experience only ambient temperatures."

The findings are published in the journal Global Change Biology.