Cooperative Extension Publications

By Christine R. Maher, Ph.D., Professor of Biology, University of Southern Maine
Britney Evangelista, B.S. Department of Biology, University of Southern Maine
Anne Lichtenwalner, DVM, Ph.D., University of Maine Cooperative Extension
Carly Sponarski, Ph.D., Assistant Professor of Human Dimensions of Wildlife and Fisheries Conservation, University of Maine

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Natural History

To manage woodchucks effectively on your property, it helps to understand some things about their biology and natural history. We’ll start with a question – what’s the difference between a woodchuck and a groundhog? Nothing! People use both names. Another name for them is “whistle pig”, which refers to their high-pitched alarm calls given when they detect a predator nearby.

The scientific name for woodchucks is Marmota monax, which tells you that they are marmots. More broadly, woodchucks are rodents, sharing the order with beavers and mice. They also are squirrels, counting chipmunks and tree squirrels as kin. In fact, they are large ground squirrels and related to prairie dogs. They are one of 14 species of marmots that occur across the Northern Hemisphere, with woodchucks having the largest range of any marmot. They occur across the eastern third of the U.S., extending as far south as the Carolinas and northern Georgia and they occupy a swath across Canada all the way to Alaska.

Annual cycle

Although their annual cycle varies somewhat depending on latitude, woodchucks follow a similar schedule across their range. Collectively, marmots are the largest true hibernators. Woodchucks emerge from hibernation in late winter or early spring, often before the snow melts, which may involve tunneling up through deep snow to reach the surface. Adult males usually emerge first, and they roam the area, re-establishing territories and looking for females. If males encounter each other, they defend their territory, using threats, chases, or fights to repel the intruder. Adult females emerge next, and then mating season begins. Males court females using soft vocalizations, while females generally ignore, avoid, chase, and eventually mate with them. Females may mate with more than one male, and males mate with more than one female.

After a pregnancy that lasts for 30 days, pups are born in the female’s burrow. They develop quickly and first emerge above ground when they’re about 4 weeks old. They are weaned soon thereafter and can fend for themselves. Because they must prepare for hibernation in a few short months, females only have time to produce one litter each year, with an average of 4 pups per litter.

During the early part of the active season, woodchucks often continue to rely on fat stores because, in some areas, food won’t appear until after snow melts and plants start to grow again. Once mating season ends, adult males can focus on storing fat for the onset of another winter. Adult females, however, face the energetic demands of pregnancy and nursing, so they don’t start to store fat in earnest until early summer, after pups are weaned. Nonetheless, they quickly catch up to males. By the time woodchucks enter hibernation in late summer or early fall, they may double their weight from the spring. Juveniles get a later start on growth compared to adults, so they enter hibernation last. In the following spring, they emerge a few weeks after the adults did.

Diet

As gardeners know, woodchucks are vegetarians. They generally avoid grasses, which are tough, fibrous, and loaded with chemicals that plants use for protection against herbivores. Instead, woodchucks focus on forbs, i.e., nonwoody perennials. Among their favorites are dandelion and clover, especially the flowers. They also feed on young leaves of some shrubs, including blackberries and raspberries.

Predators

Woodchucks also have predators. Most commonly, they fall prey to canids – coyotes, red foxes, gray foxes, and domestic dogs. Juveniles also can be captured by raptors such as red-tailed hawks.

Habitat and burrows

Woodchucks usually are associated with edge habitat, living in areas that contain both forest and meadow. They often hibernate in the forest, where tree cover provides some protection from harsh winter climates. Come spring and summer, they venture out into the meadows, which are prime feeding areas, returning to the woods at the end of the season to hibernate again.

Woodchucks construct burrows that can extend 1 m (~39”) deep and 10 m (~50’) long. Most systems have multiple entrances, with a conspicuous main entrance that is often marked by a “porch,” a large pile of dirt that they excavated.

Hidden nearby are “plunge” or escape holes that lack the dirt pile. Within the burrow system, a woodchuck excavates a nest chamber, which it lines with dried grasses and leaves, and a separate latrine chamber. Although woodchucks typically occupy burrows in loam or sandy soil, they also climb trees – like a squirrel – although they are not nearly as graceful or daring as a gray squirrel or red squirrel clambering among tree branches.

Armed with this background about woodchuck biology, we now can talk about ways to manage them on your property.

Survey results

We surveyed Maine residents to learn more about the methods they use to manage woodchucks, both successfully and unsuccessfully. Most respondents lived in rural areas (77%) on more than one acre of land (77%). Furthermore, 25% maintained a vegetable garden, 14% had flower gardens, and 19% lived on a farm.

Techniques to Avoid

Trapping and relocating

Let’s start with what not to do! Many homeowners do not want to see animals hurt, and they do not want to shoot or trap and kill woodchucks. Instead, people use live traps and then transport and release the animal elsewhere, with humane intentions. Unfortunately, such practices are not humane for several reasons.

First, translocation involves releasing an animal far from its original home, into unknown areas. If the habitat is suitable for release, then other woodchucks already may live nearby. Woodchucks are territorial, and the territory owner is unlikely to tolerate an intruder. Thus, the new arrival must keep moving until it finds an unoccupied area. In the meantime, it lacks information about burrows and other safe refuges from predators. Furthermore, as it moves, it may encounter other hazards, including roads and vehicles, which lead to death.

Releasing the animal onto someone else’s property often requires permission, and it simply transfers the “problem” to someone else. In addition, there is the remote possibility that a translocated woodchuck carries disease, which could be spread. For all these reasons, translocation is probably not a good idea.

Poisons

Few people are willing to use poisons to control woodchucks, with good reason. Poisons can be dangerous to handle, and they do not discriminate. Thus, poisons may kill non-target animals, including cats and dogs. They also can endanger children who accidentally encounter poisons in their yards or households.

Successful Techniques

Shooting

Not surprisingly, two successful methods for managing woodchucks were also lethal techniques: shooting and predators. In particular, rural residents were more likely (21%) to report successfully controlling woodchucks by shooting them. However, because of firearms restrictions and safety concerns, shooting is not a viable or desirable option for all people.

Predators

Some people rely on other animals to manage woodchucks, such as coyotes, foxes, and domestic dogs. However, predators were as likely to be successful (16%) as unsuccessful (14%). Predators can be quite effective at killing woodchucks, especially juveniles that are smaller and less experienced than are adults. However, woodchucks can escape in their burrows or take defensive measures such as using their formidable teeth and claws to deter a sensible dog that is not highly motivated to kill to gain a meal. Furthermore, predators are not always available; coyotes and foxes may not live nearby, and for many reasons, some people choose not to keep dogs as pets.

Repellants

Most survey respondents (22%) reported that applying repellants or using strong odors such as moth balls or ammonia did not deter woodchucks. However, research conducted elsewhere showed that repellants, particularly predator odors such as bobcat or coyote urine, can be effective against woodchucks. Furthermore, 10% of respondents claimed success with repellants.

One key to success is technique. Rain and time can diminish the strength of odors, so these substances must be reapplied regularly. Woodchucks also may habituate to predator odors, especially without any other cues about a predator’s presence, so it may be beneficial to apply the odors in different areas and at different times to “convince” the woodchuck that the predator remains in the area.

Fences

Another successful technique is fencing. People reported that electric fences, chicken wire, and hard wire fencing were most likely to keep woodchucks out of an area. On the contrary, other people reported less success with these types of fencing. Again, technique matters, and fences must be deployed properly to be effective.

Woodchucks quickly learn to test a fence. They can squeeze through gaps, and juveniles can fit through large mesh sizes. Woodchucks are burrowing animals, so digging is natural for them. They also can climb a sturdy structure to reach tempting foods on the other side. Thus, it is important to bury fences 12” below ground and use materials that are somewhat loose or flexible to prevent climbing. Some people use bird or deer netting at the top, which provides an unstable surface that woodchucks cannot grasp to climb over. It can be helpful to bend the bottom of the fencing at a 90° angle, extending away from the garden for 12” or more, which further deters digging. Indeed, people who used fences successfully reported that they buried fences or laid rocks along the base to prevent digging.

Landscape modification

Another approach that can be successful is to alter the environment, making it less appealing in some way. Some people found that blocking or filling in the woodchuck’s burrow worked (14%); however, more people reported that such practices did not work (21%). Again, woodchucks burrow, and their natural instinct is to dig. Thus, if they are living in a suitable area with plenty of food nearby, they may be motivated to return to an existing burrow. As we mentioned earlier, technique matters.

Filling a burrow with loose soil or sand may be too easy for a woodchuck to remove. Filling it with more solid, less moveable objects may be more effective. However, a determined animal may dig around large rocks. Furthermore, the woodchuck should not be present in the burrow at the time, because then it opens the hole to escape. Thus, people may need to monitor the hole and fill or block it after the animal has left.

Other methods that people reported as successful include providing an alternative food source nearby. For example, some people locate the compost pile at some distance from their garden, which may encourage a woodchuck to feed there, especially if the garden is fenced and thus more difficult to access than the compost pile. Other people plant extra, knowing the woodchuck will eat some plants.

Conclusions

Woodchucks can cause headaches for property owners when they invade a garden or burrow under a shed. However, woodchucks serve important ecological roles. They themselves are food for other animals, including foxes, hawks, and coyotes. Their burrows serve as homes to other animals such as skunks, mice, and chipmunks, and foxes or coyotes may take over abandoned burrows for their own dens. If a homeowner has a problem animal, then the best way to manage it is to encourage it to move elsewhere, by removing food sources through fencing or otherwise creating a less favorable environment in which to live.

Questions should be directed to Griffin Dill or your local Cooperative Extension county office.

References

Eaton, A.T. 2017. Dealing with Woodchuck Damage. University of New Hampshire Cooperative Extension.

Kwiecinski, G.G. 1998. Marmota monax. Mammalian Species 591:1-8.

Swihart, R.K., Mattina, M.J.I., & Pignatello, J.J. 1995. Repellency of predator urine to woodchucks and meadow voles. National Wildlife Research Center Repellents Conference. 35: 271-284.

Acknowledgments

Funding provided by the University of Southern Maine Undergraduate Research Opportunity Program.

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Information in this publication is provided purely for educational purposes. No responsibility is assumed for any problems associated with the use of products or services mentioned. No endorsement of products or companies is intended, nor is criticism of unnamed products or companies implied.

© 2020

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