Fatter, and happier: the yellow-bellied marmot of the Rockies.

Warmer temperatures in the Colorado Rockies have produced a population boom of yellow-bellied marmots, at least in one well-studied valley.
In an unusual, long-term study, scientists have been tracking marmots there since 1962. A new paper compares marmots from 1976 through 2008 to look for the effects of global warming on the animals.

Over that time, the winter thaws have been arriving sooner, and the marmots have been emerging out of hibernation earlier — the first sighting of a marmot now comes around April 20, a month earlier than in 1976.

That gives them more time to eat and grow, and the result is that a female marmot was on average about 7.6 poundsduring the second half of the observational period, about three-quarters of a pound more than the average in earlier years, researchers reported in the current issue of the journal Nature.

Until 2000, the population remained steady at about 100. But as the marmots got heavier and the winters shorter the percentage surviving winter hibernation rose to 80 percent from 70 percent. The population has since tripled.
By KENNETH CHANG via The New York Times