MSGID: 1:317/3 647035f5   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    Arctic ground squirrels changing hibernation patterns    
    Unique long-term study helps us understand biological responses to   
   climate shifts    
      
     Date:   
         May 25, 2023   
     Source:   
         Colorado State University   
     Summary:   
         New research analyzes more than 25 years of climate and biological   
         data.   
      
         The findings include shorter hibernation periods in arctic   
         ground squirrels, as well as differences between male and female   
         hibernation periods.   
      
      
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   FULL STORY   
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   Arctic ground squirrels are unique among mammals. Their ability to   
   keep from freezing even when body temperatures dip below that mark on   
   the thermometer enables them to survive extreme winter climates. New   
   research published in Science analyzes more than 25 years of climate and   
   biological data. The findings include shorter hibernation periods and   
   differences between male and female hibernation periods. Spoiler alert   
   -- the girls "rise and shine" a little earlier in response to warming,   
   which could have both positive and negative ripple effects throughout   
   the food web in these ecosystems.   
      
   Senior author Cory Williams, assistant professor in the Department of   
   Biology at Colorado State University, began studying arctic ground   
   squirrels while at the University of Alaska Fairbanks more than 15   
   years ago. "I think the thing that makes our study unique is that we are   
   looking at a long enough dataset to show the impacts of climate change   
   on a mammal in the Arctic," said Williams, who joined the CSU faculty in   
   2021. "We can show a direct link between changes in temperature and the   
   physiology and ecology of these animals."  Helen Chmura, lead author for   
   this latest research, started the analysis while a postdoctoral fellow   
   at the University of Alaska Fairbanks in 2018 and now works as a USDA   
   Forest Service researcher with the Rocky Mountain Research Station. "Our   
   data show that the active layer, the soil layer above the permafrost,   
   freezes later in the fall, doesn't get as cold in the middle of winter,   
   and thaws slightly earlier in the spring." She added, "These changes,   
   amounting to about a 10-day reduction of the time soil is frozen at a   
   meter deep, have occurred over just 25 years, which is fairly rapid."   
   Arctic ground squirrels survive harsh Alaska winters by hibernating   
   for over half the year, drastically slowing their lungs, heart, brain,   
   and body functions. They still must spend energy to generate enough   
   heat from stored fat to keep tissues from freezing. They resurface from   
   their burrows more than 3 feet below the ground each spring, famished   
   and eager to mate.   
      
   Chmura and Williams, along with co-authors, analyzed long-term air and   
   soil temperature data at two sites in Arctic Alaska in conjunction with   
   data collected using biologgers. They measured abdominal and/or skin   
   temperature of 199 free-living individual ground squirrels over the   
   same 25-year period. They found that females are changing when they end   
   hibernation, emerging earlier every year, but males are not. Changes in   
   females match earlier spring thaw.   
      
   The advantage of this phenomenon is that they do not need to use as much   
   stored fat during hibernation and can begin foraging for roots and shoots,   
   berries and seeds sooner in the spring. Scientists think this could lead   
   to healthier litters and higher survival rates.   
      
   The downside is that if the males also do not shift hibernation patterns,   
   there eventually could be a mismatch in available "date nights" for   
   the males and females. Ground squirrels are also an important source of   
   food for many predators, such as foxes, wolves, and eagles. An indirect   
   consequence of being active above ground longer is greater exposure and   
   risk of being eaten.   
      
   What will happen to the population is a big unknown - there are not   
   clear winners or losers. While hibernation requires less energy, which   
   could help overwinter survival, ground squirrel numbers also depend on   
   how predators respond to climate shifts. For now, Williams concludes,   
   "Our paper shows the importance of long-term datasets in understanding   
   how ecosystems are responding to climate change." Chmura agreed, adding,   
   "It takes a great team to continue a dataset like this for 25 years,   
   especially in the Arctic."  Other contributing authors include Brian   
   Barnes, University of Alaska Fairbanks, and Loren Buck from Northern   
   Arizona University, who both began this study in the 1990s to learn how   
   Arctic ground squirrels survive such long, cold, dark, winters and just   
   how cold their hibernation spots were. These questions prompted them to   
   install the first soil temperature monitors, and as technology improved,   
   they were able to measure those temperatures all winter long. Cassandra   
   Duncan and Grace Burrell assisted with the research while students at   
   the University of Alaska Fairbanks.   
      
       * RELATED_TOPICS   
             o Plants_&_Animals   
                   # Soil_Types # Biology # Nature # Organic   
             o Earth_&_Climate   
                   # Global_Warming # Climate # Tundra # Weather   
       * RELATED_TERMS   
             o Mesozoic o Weather o Mule o Arctic_fox o   
             Ice_age o Endospore o Organic_farming_methods o   
             Temperature_record_of_the_past_1000_years   
      
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   Story Source: Materials provided by Colorado_State_University. Note:   
   Content may be edited for style and length.   
      
      
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   Journal Reference:   
      1. Helen E. Chmura, Cassandra Duncan, Grace Burrell, Brian M. Barnes,   
      C.   
      
         Loren Buck, Cory T. Williams. Climate change is altering the   
         physiology and phenology of an arctic hibernator. Science, 2023;   
         380 (6647): 846 DOI: 10.1126/science.adf5341   
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   Link to news story:   
   https://www.sciencedaily.com/releases/2023/05/230525141359.htm   
      
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