Thursday, August 9, 2012

Climate Change and the Columbian Ground Squirrel

The Columbian ground squirrel is found in high meadows and grasslands of eastern British Columbia and western Alberta in Canada, and parts of Oregon, Washington, Idaho, and Montana in the United States. These ground squirrels live in colonies, spending four to five months of the year eating grasses, leaves, bulbs, fruits and seeds, and raising their litters of three to five young.

The other seven or eight months they spend hibernating. Each squirrel's burrow has a hibernation chamber. Columbian ground squirrels may begin hibernation in some areas as early as July. During the warm months, each squirrel puts on sufficient fat to survive the winter, and gathers seeds and bulbs in its burrow to eat when it wakes up. When hibernation begins the squirrel will seal the chamber with a plug of dirt. It will not emerge until the following spring.

Is it spring yet?

Now research is suggesting that global climate change is altering the hibernation patterns of the Columbian ground squirrel, with troubling implications. A team of scientists followed a group of female squirrels in Alberta over a period of twenty years. They have found that by 2011, the squirrels were emerging from hibernation an average of ten days later than at the beginning of the study.

The researches believe that the reason for the later emergence is a trend toward wetter, snowier winters in the region. They believe that the squirrels can detect the presence of snow cover from inside their hibernation chambers. Global warming is creating favorable conditions for later snowfall, and as a result the squirrels hibernate longer and emerge later.

The troubling aspect of this research is that with the longer hibernation, fewer of the ground squirrels are surviving the winter sleep. At the beginning of the project, twenty years ago, 87 percent of the female squirrels survived the winter hibernation. By 2011, only 67 percent of the females that entered hibernation emerged the following spring. The scientists aren't sure of the reason, but speculate that the shorter period above ground means that there is less time for the squirrels to put on the body fat required to survive the winter.

Whatever the reason, the fact is that fewer of these ground squirrels are surviving their winter hibernation, and this trend is not likely to reverse any time soon. It is one more piece of evidence of the damage that human-created climate change is doing to our planet.

Addition: Here is another, more detailed article about the Columbian ground squirrel study. It gives more information on the relationship between emerging later from hibernation and the increased failure of the squirrels to survive. It also gives a more complete explanation of the relationship between climate change (global warming) and increased late-winter and early-spring snowfall.

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