Prognosticating Mammals

One of my favorite facts about that most famous of prognosticating mammals, Punxsutawney Phil, is that he’s wrong in predicting the spring weather more 61% of the time!! That’s a pretty terrible track record. Perhaps his handlers just don’t speak marmot as well as they think they do. Well, here in Burlington, we’ve got our own prognosticator, the Wiley Whistlepig, Burly Burnard himself. I set a camera up on his doorstep a few weeks ago (with his permission of course), and was surprised to see that even in cold weather (14 degrees cold), this woodchuck was out collecting materials to spruce up his den.

I’m not convinced that animals have any particularly keen sense of what the weather will be like more than a day or two in advance. Claims that dogs in San Francisco (source) or ants in the Mojave Desert (source) can predict earthquakes hours to days in advance have been debunked. And the thought that a woodchuck can predict the length of spring is beyond credible. The emergence (and subsequent disappearance) of woodchucks in late winter is less about prognosticating spring weather, that it is about a more scintillating future event.

Woodchucks (aka whistle pigs, ground hogs, and Marmota monax) are our largest ground squirrel here in New England (quiz: how many different species of squirrels are there in Vermont?). On the spectrum of active every day to dead to the world, woodchucks in winter are mostly dead to the world. They lower their body temperatures (to 40 degrees), heart rate (to <10bpm), breathing rates, and metabolic rate. While not good at predicting the future, animals are exceptionally adept at knowing when breeding season is. And indeed, woodchucks are roused from deep winter hibernation to fulfill that all important rite of spring. They unplug the entrance to their burrows and begin to emerge from their dens in February and March as an internal fire stokes their desire to find a mate.

Shortly after waking, they begin cleaning out their dens, spilling out loads of fresh earth around the entrance (this makes finding their winter dens rather easy at this time of year). They also collect and bring in fresh leaves to freshen up their beds (see video above). Though very little is in the literature about scent marking, males chew the bases of trees and young saplings to mark territory and cheek rub. Males typically emerge before females and their testes, which are internal for most of the year, expand significantly in preparation for the breeding season (March to April). Courtship involves scent marking, chasing, and boxing (yup, boxing). While gray squirrels bite the ears of females (often tearing the ears), woodchucks are a bit gentler and bite the fur on the females back during copulation. The pair stays together during gestation, but the female will kick the male out of the den just before the young are born (about a month after copulation).

I was surprised to see that the woodchuck was bunking up with another species. But then I found an advertisement Burly Burnard had posted looking for someone to share his bachelor pad with (see above). Looks like he found a roommate! Woodchuck burrows can be extensive and have multiple branches. The soils in Centennial Woods are mostly soft sands deposited by the Winooski River delta when it dumped into the Champlain Sea 10,000 years ago, a woodchuck’s dream when it comes to digging. There are 3 openings within 50′ of each other and I wonder if these 3 entrances all connect to the same tunnel system. Either way, given how extensive a woodchuck’s burrow can be, it’s unlikely that the skunk and woodchuck are cuddling together in the same chamber, but one can hope.

Sources

• Whitaker, John. Mammals of the Eastern United States.
• Ouellet, Jean-Pierre and Jean Ferron. Scent marking behavior by woodchucks (Marmota monax). Journal of Mammalogy. Vol. 69, No. 2 (1988), pp. 365-368
• Woodchuck scent marking by Janet Pesaturo (includes video)