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Arb Notes: Mammal Hibernation in the Arboretum

On February 2,  Punxsutawney Phil emerged from his burrow in a sunny Pennsylvania town. His prediction: six more weeks of cold fronts and snow flurries. Three weeks later and a thousand miles from Pennsylvania, groundhogs in the arboretum are at the tail end of a long winter spent below ground. 

Groundhogs (Marmota monax, also called woodchucks)  are true hibernators. At the dawn of winter in mid-October, the grizzled rodents nestle into extensive underground burrows that measure two-to six-feet deep and up to 40 feet long. In the following months, their body temperature drops to as low as 35 degrees Fahrenheit, their heart rate falls to a mere 4 to 10 beats per minute and their breathing rate slows to one breath every six minutes. When they emerge from their burrows in early spring, groundhogs have lost nearly half of their body weight. 

Other hibernating mammals find winter homes in the arboretum.  Named for their delicate patterning of light and dark brown stripes, thirteen-lined ground squirrels (Spermophilus tridecemlineatus)  hibernate from October to March. Unlike woodchucks⁠—which prefer wooded areas⁠—thirteen-lined ground squirrels burrow in open prairies and residential areas. Eastern chipmunks (Tamias striatus) are restless winter residents, waking from periods of deep sleep every few days to scamper above-ground and feed on stored caches of seeds and nuts. 

As Northfield emerges from another week of winter storms, a host of small mammals eagerly await warmer temperatures and the flurry of mating season from the comfort of their winter homes.

Sydney Marie Jones ‘22 for the Cole Student Naturalists

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