Is Global Warming a Boon for the Yellow-Bellied Marmot?

By Andrew Moseman | July 21, 2010 2:52 pm

marmotYellow-bellied marmots are taking to global warming just fine—so far. A Nature study of the hibernating Rocky Mountain-dwellers found that over the last 30-plus years, the marmots have grown both in girth and in population, and the researchers think they know why.

Study author Arpat Ozgul says that the marmots have limited time to accomplish the things on their summertime agenda—namely, eating, mating, and giving birth before they crawl back into their seven- to eight-month hibernation.

But as the Colorado summers have grown longer, so too has the time the marmots have to do all of these things—and do them better. This extra preparation (and reproduction) time means that “they are more likely to succeed and survive,” said Ozgul [Scientific American].

Because of the extra time, marmots studied grew in average weight from approximately 6.8 pounds to 7.5. And since 2001 the marmot population has exploded, adding an average of 14 individuals each year; in the previous 25 years the population growth rate was only .56 per year.

However, there are confounding factors that make it hard to be sure that the changes in the marmots are tied just to temperature and waking early from hibernation. Take the example Marcel Visser points out in an accompanying commentary:

The population of one of the marmot’s foods, tall bluebell flowers, began to decline in 2000, just before the marmot population surged; this might have altered the marmots’ diet, leading them towards fattier foods [Nature].

There’s such a thing as too many marmots, also. But, coauthor Daniel Blumstein says, this will probably sort itself out.

As Blumstein reminded, “before we start worrying about being knee-deep in marmots, populations of predators and prey are often linked, and we’ve had a concomitant increase in the predators (foxes and coyotes) in some of our colonies” [Discovery News].

And besides the good times for their predators, marmots face another threat: drought. They don’t cope well with drought in the late summer, so if their habitat gets drier, that could reverse the good fortune that a warmer climate seems to bring them.

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Image: Wikimedia Commons

CATEGORIZED UNDER: Environment, Living World
  • Brian Schmidt

    If they like warmer weather, then I guess the thing that keeps them from moving downhill is the lack of rocky terrain/cover from predators.

    And while they might like the moderate warming that’s occurred so far, future warming might be too much. The disappearing bluebells could be an indication.

  • Dennis R. Cooper

    The average temperature of Shelby, Montana has been falling since 1940 according to recorded temps. See: and type in average temp Shelby, Montana and click current week and select all. It is one of the towns that have not moved their therometer to a roof or paved parking lot. (-0.046 deg F/yr average drop)

  • Dennis

    Hey, nice marmot!

  • Nick

    Hey, I saw that Marmot last week when I went up to Mt. Evans in CO!

    On a different note: This may help explain why our polar bear count is on the rise.

  • Chris the Canadian

    Looks like a Groundhog to me. Cute lil bugger. Just a question: are dieticians going to start griping that the Marmot population is overweight or obese?

  • m

    yes…a cute little groundhog that….BANG!

    heh! got him!!! Sandwiches anyone?

    As for the polar bears…amen to that. I’ve never seen so many. Then again…this is the 4th cooldest summer in a row here in beautiful NWT.

    but hey…lets not overshadow “global warming nazis” with…you know…facts.

  • SpenceGrant

    He looks comfortable sunbathing.


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