PARIS — Global warming has been rough on polar bears, but for Colorado's marmots it has meant more food and more sex, according to a unusual study released on Wednesday.
Longer summers -- and less time spent burning up stored fat during hibernation -- have given the large burrowing rodents an evolutionary leg up, said the research, published in Nature.
Not only has climate change made individual specimens heavier and healthier, it has led to a marmot baby boom as well.
Yellow-bellied marmots are awake only four-to-five months of the year, which doesn't leave a lot of time to take care of essential business, explained the study's lead author Arpat Ozgul, a scientist at Imperial College London.
"They have to eat and gain weight, get pregnant, produce offspring and get ready to hibernate again," he said in a statement.
"Since the summers have become longer, marmots have had more time to do all these things and grow before winter, so they are more likely to succeed and survive."
The study is the first to show, for any species, that a shift in seasonal timing can cause changes in body mass and population size at the same time, he said.
Analysing data collected over 33 years starting in 1976, Ozgul and colleagues observed that the average weight of adult marmots increased from 3094 grams in the first half of the period to 3433 grams in the second half -- about a ten percent increase.
To gather the data, the scientists live-trapped wild marmots at different colonies in the Rocky Mountains and marked them with numbered ear tags, recording sex, mass and, for females, reproductive condition.
Population swelled over the last decade, rising from one new member every two years during the period 1976 to 2000, to more than 14 additional marmots every year from 2001 to 2008.
While the animals appear to have benefited from rising temperatures in the short run, the good times may not last, the researchers warned.
"Will populations thrive in the changing climate? We suspect that this population increase is a short-term response," said Ozgul.
Brian Hoskins, director of the Grantham Institute for Climate Change, compared the Rocky Mountain marmots to 'canaries in the coal mine.'
"They give us an early warning about the effect for climate change on our natural environment," he said.
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