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Warmer Winters Threaten Hibernating & Torpid Mammals

12-6-13 eastern chipmunk IMG_2845Winter air temperatures have increased in the Northeast during the past 100 years. A study by Craig Frank of Fordham University has found that as winter temperatures heat up because of global warming, chipmunks in areas that have experienced warmer winters become less likely to hibernate in the coldest months. The research indicates that chipmunks that follow normal hibernation procedures enjoy a survival rate through winter of about 87 percent, while those that remain active because of warm winter weather are almost certain to die by spring (due to higher metabolism requiring more food). This finding could mean dire consequences for all mammals that hibernate or become dormant during winter months, as exceptionally high winter temperatures correlate positively with reduced hibernation, resulting in a lower winter survival rate for these animals.

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13 responses

  1. Hm, I find this strange, because eastern chipmunks range into the southeast, where they probably remain active for all or most of winter, and can make it because energy requirements are less during warmer southern winter. If winter weather is warmer up here, they should not need as much food. I guess what that research says is that though winter weather may be warmer now, there is still not enough available food to get these animals through winter.

    December 6, 2013 at 2:35 pm

    • I’m not sure if I understand exactly what you’re saying, Janet, but chipmunks become torpid in the northeast in winter, lowering their metabolism greatly, and thus reducing their fuel requirements. A rise in temperature would bring them out of torpor, raise their metabolism and require them to eat more than they would if they were only waking up every couple of weeks to eat.

      December 6, 2013 at 5:57 pm

      • No, I meant that energy requirements of an awake animal in a warmer winter would be less than energy requirements of an awake animal in a colder winter. So my question was, since we know chipmunks can survive southern winters while staying mostly active, why can’t they survive staying mostly active in north during a warmer winter.

        Then I tried to answer my own question by positing that perhaps there is just not enough food in the north for them to endure a winter. There probably are more acorns, nuts, etc. in southern forests.

        December 7, 2013 at 1:49 pm

      • Exactly, Janet!

        December 7, 2013 at 2:14 pm

      • Alonso Abugattas

        It sounds like you’re suggesting that there would not be enough winter food for chipmunks in their more northern parts of their range, less mast crops like acorns and hickories? Not sure I have heard that difference in nut production before. It also seems that there is sufficient food for much larger mammals that also eat these foods as a main food source (even with the more northern populations having much larger individuals than their southern relatives, Bergman’s rule I believe) like deer and bear. There maybe a lot of factors involved, but I’m not sure food is a primary factor in winter, especially from a hoarder like chipmunks that seem to do alright in their southern portions of their range. Of course I could be wrong and their could be so many other factors involved as well. I thoroughly enjoy the postings and was only wondering myself.

        December 8, 2013 at 5:58 am

      • Hi Alonso,
        The research I am familiar with did not go into the specific reasons for the potentially decreased survival rate in the north, should global warming continue its trend. I appreciate hearing your thoughts! Mary

        December 8, 2013 at 1:54 pm

  2. Alonso Abugattas

    I agree that although some individuals may be affected, the population has a much broader range that extends into the South and therefore can inherently deal with these conditions. Not sure how this would affect the whole population rather than just a few individuals. Would be curious to see what other factors are at stake or are not being considered.

    December 6, 2013 at 3:33 pm

    • Yes, this is exactly what I was trying to say in my comment above.

      December 7, 2013 at 1:50 pm

  3. Excellent photo and discussion. Very timely information, as I have been observing erratic/delayed torpor in chipmunks and wondering about the significance of this behavior. I would weigh in with another thought, that of increased vulnerability to predation when active at this time of year.

    December 6, 2013 at 3:37 pm

  4. Reblogged this on Nick's Nature Pics.

    December 6, 2013 at 3:38 pm

  5. Kathy Swift

    I would like to contribute to Naturally Curious, but dont want to use my credit card on line. Is there somewhere I could send a check? made out to whom? Kathy Swift

    December 6, 2013 at 5:30 pm

    • I’ll send you my mailing address via email, Kathy. Thanks so much.

      December 6, 2013 at 5:53 pm

  6. Margaret Watkins

    Thank you so much for raising this issue of impacts to NH’s native wildlife from climate change. It is so important that people begin to understand connections like the one you observed in this post in order to appreciate the enormity of the changes to come if we continue on our current energy path.
    I love your blog.
    Margaret Watkins

    December 7, 2013 at 1:03 pm

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