Home » Animal Behavior » Wily Hole Digger

Wily Hole Digger

Forget Groundhog Day! It’s a scam. Around here most woodchucks don’t appear until March, although we have recorded them as early as February 25. But March is the official wakeup month for most Pennsylvania woodchucks and when they emerge they are interested in sex, not in predicting the weather.

First the males appear and wander from den to den in search of receptive females. Then, a couple weeks later the females unplug their den holes so the males can consort with them. After mating with one female, a male moves on to another. If a mating is successful, thirty-two days later a female gives birth to between two and nine naked, blind youngsters no bigger than an adult red-backed vole.

The young are born in their mother’s nest chamber, a part of her larger burrow system which can be as long as 50 feet and as deep as 12 and which also contains separate hibernating and latrine chambers. Both the hibernating and nest chambers are lined with dead leaves and grass.

Back on April 12, 1993 I watched a female woodchuck gather a mouthful of leaves and grass and carry it down into her burrow. Five days later I put my head down at the burrow entrance and listened. A continual series of piercing, high-pitched cries emanated from the burrow, a signal that the young had been born.

Trying to observe woodchuck burrow life has been difficult for biologists. Consequently, not much is known about their underground life. Mostly they live alone, hence their scientific name Marmota monax which means “solitary marmot.” The female raises her young by herself, a process that takes two months. At four weeks of age they open their eyes and are able to forage near the burrow entrance. At five to six weeks they are weaned and two weeks later they are on their own.

A popular woodchuck burrow at our Far Field thicket has been inhabited most years by a female woodchuck. On May 25, 1990 I watched two young woodchucks foraging in the weeds less than 15 feet from where I stood. They never did see me and for the first time I actually had a look at juvenile woodchucks.

Like all youngsters, they had cute faces, but they already possessed an adult’s alertness, several times leaping on to fallen trees to look for enemies in between shoving green stuff into their mouths with their dexterous front paws just as adults do. Finally the one closest to me turned around and trundled back toward the other young chuck who was foraging much nearer to the den entrance. It rushed toward its sibling and chased it down into the burrow. Then it took over and fed in the spot vacated by its less aggressive sibling.

At that same den, two years later on June 6, I surprised two young woodchucks and their mother foraging outside. She seemed unable to figure out where or what I was, but she lived up to her nickname “whistle-pig.” Sitting on her back haunches, she emitted a high-pitched whistle followed by a rapid, nine-syllable, lower trill described by William J. Hamilton, Jr. and John O. Whitaker, Jr. in Mammals of the Eastern United States as “softer chuckling notes.”

Her young immediately went down into the burrow, but she remained outside. Even as I eased myself from a kneeling to a sitting position, brought out and peered through my binoculars, and wrote notes, she continued her “whistling” call several dozen times with about seven seconds between whistles. Finally she retreated halfway down her burrow, still whistling until I left the area.

Whistling by woodchucks has been well documented. So has the growling and teeth chattering I’ve heard when woodchucks fight. But last March I heard an entirely new sound. I had surprised a woodchuck in the middle of First Field and it had run down into its burrow. Then, as I walked toward it, the woodchuck popped its head out to look around and I froze in place. Even though woodchucks are supposed to have excellent vision, I have learned that if I stand still and the wind is right, woodchucks will not see me no matter how close they are.

Up and down like a periscope its head went as it slowly peered in every direction for many long minutes while I watched from 25 feet away. Then the wind picked up, clouds totally blanketed the formerly cloudless sky, and the thermometer dropped like a bomb. Still I watched as the woodchuck, after many more “up periscope” looks, eased most of its body out of its burrow. By then I was chilled to the bone so I walked deliberately toward the creature. It dove down into its burrow. As I reached the burrow entrance, I heard a loud noise coming from underground that sounded like a whinnying horse. None of the sources I later checked mentioned such a noise.

In fact, except for the volumes that have been written about Groundhog Day, woodchucks have not been a popular subject with nature writers, journalists, or biologists. I must admit that they have been my least-favorite wild creatures too, especially during the years when we had a large vegetable garden and no dog. No matter how deeply we buried our nine-foot-high garden fence and weighted it down with rocks, woodchucks always managed to dig under it. One spring a single woodchuck ate 50 broccoli and cauliflower plants in half an hour. Another summer our son David tried to defend his garden by shooting every woodchuck he caught inside the fence. After 25 deaths, he gave up.

Now that we buy our vegetables at the local farmer’s market we are able to appreciate the horde of woodchucks who live everywhere on our mountain–in the deep woods of the hollow, the dry oak forests on both Sapsucker and Laurel ridges, the First and Far fields, and the several mountaintop thickets. Furthermore, at least five live in the vicinity of our house–under our front porch, below the back porch in the grape tangle, beside the garage, next to the road drain, and under the guesthouse.

I’ve found them outside our back door investigating the doormat, tearing across our veranda while I sat nearby, and parading over the tiny guesthouse front porch. They graze on our roughly shorn lawns and our flower beds and even eat the crownvetch we foolishly planted on the steep back slope shortly after we moved here. Like white-tailed deer, woodchucks eat a wide variety of both cultivated and wild plants, but they also occasionally relish grasshoppers, snails, June beetles and other invertebrates.

Before Europeans settled America, a much sparser population of woodchucks lived in the woods. Not only was it harder for them to make a living in such a habitat, it was difficult to escape their major predators–black bears, mountain lions, wolves, and fishers. Then settlers cut down the forests, eliminated the large predators, and planted succulent crops of alfalfa, clover and other woodchuck-friendly foods. The living was (and is) easy except for the occasional woodchuck hunter, car, or smaller predators such as dogs, foxes, minks, weasels, large hawks and owls. However, woodchucks fight so fiercely when they are cornered that such predators often retreat.

Researcher Robert Snyder has also discovered that woodchucks are susceptible to many of the same diseases as humans are–hepatitis, liver cancer, arteriosclerosis, heart attacks, strokes, even high blood pressure, so they have become popular drug-testing laboratory animals. Nevertheless, there is still one woodchuck for every five to ten acres in the Northeast and the all-time woodchuck population explosion occurred at Letterkenny Ordnance Depot near Chambersburg back in the 1950s when Snyder and others estimated that 9,000 woodchucks lived on 10,000 acres.

The woodchuck population density on our homegrounds is even higher. We’re talking five dens on less than an acre. So we occasionally witness what we assume are turf battles in late spring and early summer when youngsters are looking for new homes.

On June 11, 1991 at 2:25 p.m. I watched from the upstairs bathroom window as a large woodchuck chased a smaller one up the driveway, grabbed it briefly, and tried to tussle before it broke away and tore across the lawn toward the grape tangle. The larger woodchuck pursued it halfway across the lawn and then reared up on its haunches to look around before lowering itself and trotting back up the driveway headed for the garage.

The following May, as I sat on the veranda in mid-afternoon quietly writing, I was suddenly interrupted by the fighting of two adult woodchucks six feet away in the grass off the end of the veranda. It looked as if the front porch woodchuck was defending its territory from the grape tangle woodchuck.

When I jumped up, the woodchucks growled loudly at each other before separating. One ran under the front porch while the other dashed the length of the veranda and around the back of the house to the grape tangle. Once again the grape tangle woodchuck had gotten the worst of the fight, although I had no way of knowing whether it was the previous year’s grape tangle woodchuck or a new resident.

Last May, our son David heard growling under the guesthouse in mid-morning and went outside to investigate. One large and one smaller woodchuck emerged from beneath the house fighting and ended up in the stream. As David watched, the larger one beat up the smaller one and then headed back toward the house. When it saw David it took off down the road, water streaming from its coat. In July he witnessed another fight near the guesthouse. That time the vanquished chuck climbed a tree.

That July fight was the latest one we have watched. By mid-summer woodchucks are more interested in eating than fighting. Then they seem like gluttons as they shove food into their mouths with jerky movements that remind me of a Charlie Chaplin movie. By late September our woodchucks look like obese shag rugs. Such eating is necessary, though, because they must increase their weight at least 30% before they move into their dens, plug all the entrances with dirt, curl up into a ball in their hibernaculum, and sleep for four or more months.

Although the latest date I have recorded a woodchuck abroad is November 13, most are hibernating by late October. Along with bats and jumping mice, woodchucks are true hibernators. Their body temperatures drop to 40 degrees Fahrenheit, their breathing slows way down and their hearts beat only four times a minute. Because of the earthen plugs, their dens remain a snug 56 degrees no matter what the temperature is outside.

It’s ironic that woodchucks are the center of attention on Groundhog Day when most are still deep in hibernation. On the other hand, their ability to hibernate is their most interesting behavior characteristic. Instead of celebrating the fairy tale belief in their ability to predict the weather, we should celebrate their true ability to sleep away the winter.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s