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Losers: MarmotsA marmot takes a snack break in front of Washington State's snow-capped Olympic mountain range. Like most species, these burrowing rodents—cousins of the squirrel—have a limited range of weather they can adjust to.Usually found in cool high-altitude locations, marmots rely on a thick, insulating blanket of snow during hibernation to stay warm—and on summer vegetation to stay rotund. A long winter or a lack of snow can be a roadblock to survival, as can dry summers, which produce little food, or too much spring rain, which deters mating.Much to the marmot's dismay, the western U.S. this year saw minimal snowfall, followed by record heat and prolonged drought. (Related: "Warm Spring May Mean Drought and Wildfires in West.")Such extreme conditions, especially in the Rocky Mountains, have made a significant dent in marmot populations, according to Daniel Blumstein, chair of the Ecology and Evolutionary Biology Department at the University of California-Los Angeles, who runs a marmot research site in Colorado.Blumstein warns that it won't be global warming's gradual temperature increases that will cause massive population die-offs in the animal world. Instead, it will be the increased frequency of extreme weather events.Unfortunately, those extremes may be the new normal. As Earth heats up, there will likely be more heat waves, droughts, even rain—due to higher rates of ocean evaporation and more moisture in the atmosphere. (Read "Weather Gone Wild" in the latest issue of National Geographic magazine.)While this year started off bad for marmots, it may actually end up OK, Blumstein explained. Recent rain in the Rockies has encouraged edible plants, helping marmots add weight and focus more on breeding.—Tasha Eichenseher

Photograph by Erin Huber, National Geographic My Shot