Changing Climate Produces Bigger Marmots

Colorado yellow-bellied marmots have grown larger and increased in number in the last few decades, according to a new study published in Nature. The study, spanning 32 years from 1976-2008, points to climate change as the cause of the increasingly robust marmot population. During the last few decades, warmer temperatures have led to an earlier spring and longer growing season in Colorado. Local marmots have responded to this seasonal shift, emerging from hibernation earlier to an abundance of food, allowing them to gain more fat and reproduce earlier in the season.

Average marmot weight increased from 6.82 pounds to 7.56 pounds from 1976-2008. The change in population growth during this time is even more impressive: from 1976-2001, population growth was 0.56 marmots per year. From 2001-2008, population growth was 14.2 marmots per year. But continuing climate change may hurt the marmots in the long run, as Colorado is projected to become much drier, leading to a reduced food source for these small mountain rodents.

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