Why Woodchuck’s Whistle

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Waking up at sunrise, a long stretch, and a vigorous cheek rub in the dirt and on nearby shrubs are all part of the typical woodchuck (Marmota monax) morning routine.  While the face rub in the dirt may seem strange, it is a critical part of a woodchuck’s world.  Woodchucks are one species in the marmot genus and like most marmot species woodchucks are territorial, but unlike other marmots woodchucks are solitary.  The oral scent glands located on the sides of their face are used to mark territorial boundaries and identify offspring and other kin when woodchucks encounter each other.  A single woodchuck adult will defend a territory, although females will often live with their female offspring from the year before.  The males aren’t tolerated and are promptly sent off to find their own place once they grow out of needing their mother’s care.  Male territories will often overlap with several females, but the territories and burrows are still separate and encounters outside of the mating season can be hostile.

Most other marmot species live in loose colonies that defend a common territory, share some resources, and sometimes colony members will even hibernate in the same burrow.   These species, like yellow-bellied marmots (Marmota flaviventris), also use alarm calls to alert the colony of predators in the area.  A golden eagle or even a hiker will cause a marmot to let out a piercing whistle which is quickly passed down the hillside from marmot to marmot.  Scientists think that this is an adaptation to colonial living, where more eyes equals more safety from predators.  Researchers have even investigated whether there the animal that sounded the alarm was more likely to be eaten, but it turns out the alarmer is in no more danger than the alarmee.

Woodchucks also use a whistle call to sound the alarm when a predator or other threat is spotted, which throws some cold water on the social living theory.  They don’t alarm nearly as much as other marmots, but they use their whistle enough to have earned the nickname “whistle pig” (although the yellow-bellied marmot shares this nickname in the west).  Why do woodchucks sound the alarm even when they live alone?  One reason may be that woodchucks usually live close to other woodchucks, and even though they are competing for resources it is still advantageous to all be on the lookout for predators.  There is also fascinating evidence that woodchucks listen closely for alarm calls from other small mammals, especially eastern chipmunks (Tamias striatus), and that chipmunks may also use woodchuck alarm calls as an alert system.

So the next time you see woodchucks “kissing” you can dispel that myth and explain why woodchuck’s oral scent glands are important, and if a woodchuck whistles at you don’t take offense.  He just thinks that you want to eat him.

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Sources

Aschemeier, L. M., and C. R. Maher. 2011. Eavesdropping of woodchucks (Marmota monax) and eastern chipmunks (Tamias striatus) on heterospecific alarm calls. Journal of Mammalogy 92:493–499.

Blumstein, D. T., and K. B. Armitage. 1997. Does Sociality Drive the Evolution of Communicative Complexity? A Comparative Test with Ground‐Dwelling Sciurid Alarm Calls. The American Naturalist 150:179–200.

Daniel, J. C., and D. T. Blumstein. 1998. A test of the acoustic adaptation hypothesis in four species of marmots. Animal Behaviour 56:1517–1528.

Ferron, J., and J. P. Ouellet. 1989. Temporal and intersexual variations in the use of space with regard to social organization in the woodchuck (Marmota monax). Canadian Journal of Zoology 67:1642–1649.

Meier, P. T. 1992. Social organization of woodchucks (Marmota monax). Behavioral Ecology and Sociobiology 31:393–400.

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