Does Anyone Love the Woodchuck?

A little woodchuck natural history, plus hints on how to garden with woodchucks

04-01-1997 // Les Line

What good is a woodchuck? You might have heard that kind of question asked about any wild animal in less ecologically enlightened times. But the reporter from a Michigan newspaper who phoned PurdueUniversity ecologist Robert Swihart last summer was dead serious.

Local gardeners, he said, were suffering a plague of woodchucks, and he wanted to know if there was anything positive to be said about gluttonous rodents that weigh as much as 14 pounds and can devastate a carefully tended vegetable garden in a matter of minutes.

Swihart was the right scientist to call. His woodchuck work includes discovering a nonlethal way to keep the animals from being a real problem for fruit growers.

I told the writer that the woodchuck's life history and ecology are fascinating, and that all the holes they dig provide homes for a lot of other animals like foxes, raccoons, opossums and cottontails," says Swihart, who conducted his studies of woodchucks while a researcher at the Connecticut Agricultural Experiment Station. "I grew to admire them. Well, change that to grudging admiration," he adds. "At least when they stick to their natural habitats."

If that seems like a lukewarm endorsement, the truth is that the woodchuck, or groundhog as it is also known, may be North America least-loved native mammal. It waddles across most of the eastern United States and southern Canada. Farmers consider it a nuisance. Exurbanites who build their dream houses in woodchuck land call the exterminator when the animals tunnel under the carport. The striped skunk gets more respect, especially from motorists who, judging from the carnage along rural routes, rarely brake for woodchucks licking salt or munching newly mowed grass on the roadside. And Purdue University, though not Swihart himself, provides Internet surfers with three pages of tips for eliminating the rodents.

Even on Groundhog Day, its annual moment in the limelight, the dumpy woodchuck is mainly the butt of bad jokes by television weatherpersons, or silly articles written by newbie journalists who get the assignments no one else wants. Last year, a woodchuck known as Wiarton Willie, Ontario answer to Pennsylvania Punxsutawney Phil, was in the headlines later than usual because of a death threat. Willie, unlike Phil, did not see his shadow on February 2, and according to folklore that augurs an early spring. But Willie's "prediction " didn't come true, and that angered a Canadian who was weary of a lingering winter. His anonymous letter was pasted together from clippings, just like in the movies, and police took it seriously. The woodchuck was put in protective custody.

At least that's what the papers said on what must have been a slow news day. Woodchucks, of course, can't foretell weather because of the presence or absence of a shadow. And why would a sunny day rather than a cloudy one mean six more weeks of winter? Go figure.

In fact, most woodchucks, except those living in the southeastern part of their range where the hibernation period is brief, are sound asleep on Groundhog Day--unless they've been dragged from their zoo beds for a photo op. "A hibernating woodchuck won't come out of its den in midwinter even if the temperature hits 60 degrees," says Larry Van Druff, a wildlife professor at the State University of New York in Syracuse. While the process is not fully understood, the animal's internal clock--which is controlled by hormones and synchronized to daily changes in the length of daylight and darkness--sends a call to wake up and breed at the appropriate time. That time comes in late February or early March in northern areas. Even then, VanDruff adds, the woodchuck may find its burrow plugged with snow and have to live off leftover body fat for a week or two.

For the next seven or eight months, until the days grow shorter and its winter den beckons, a woodchuck will eat anything that grows near its burrow, consuming a pound or more of food a day. And when several woodchucks inhabit an alfalfa or grain field, they can cause considerable crop loss.

However, the woodchuck-in-the-orchard problem that Swihart tackled had nothing to do with pilfered apples (a groundhog can climb a tree almost as easily as its squirrel cousins). Rather, the big rodents gnaw on the trunks during scent-marking rounds, leaving their territories ringed with dying apple trees. Swihart found that spraying the bark with predator odor--specifically, bobcat urine--reduced the gnawing behavior by 98 percent.

A rope fence strung at woodchuck nose level and hung at three-foot intervals with strips of cloth soaked in bobcat urine will do the same trick for a garden, and if you don't have a pet bobcat, trapping-supply houses sell the repellent.

VanDruff, on the other hand, had no magic answer when the National Park Service asked him to come up with a plan to cope with "an unnaturally high woodchuck density" at Antietam National Battlefield. The Civil War's bloodiest one-day battle was fought over the fields near Sharpsburg, Maryland on September 17, 1862; 23,000 soldiers died or were wounded there. For years, the park staff has waged its own battle against woodchucks there. "Farm dogs are the woodchuck's main enemy, but they're missing from our landscape," explains Ed Wenschhof Jr., the park's natural resources chief. VanDruff's three-year study suggests a number of steps that--if followed rigorously--could ease the national battlefield's woodchuck woes. They include sealing holes in critical areas with concrete or squares of welded wire. However, considering the burrowing habits of both groundhogs and bureaucracies, the probable outcome is a stalemate.

Both Swihart and VanDruff stress that it is shortsighted to view the woodchuck as a pest that should be exterminated wherever possible. Beyond their important role in the natural community, the big rodents are helping to save human lives. Wild woodchucks often are infected with a virus very similar to hepatitis B, which can hasten death from liver cancer and cirrhosis. "Humans don't get hepatitis from woodchucks," says Dr. Bud Tennant at the Cornell University College of Veterinary Medicine, which raises disease-free woodchucks for medical research. "However, the woodchuck virus and its effect on their liver is similar enough to make it the best animal we have for studying viral hepatitis in humans."

The key difference, Dr. Tennant explains, is that time is compressed. "Disease processes that take 30 to 40 years in humans occur in 3 to 4 years in woodchucks. Until the woodchuck came along, research on hepatitis B was difficult." That fact alone ought to be worth a few rows of carrots and cabbages.

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