Groundhog Day


February 1, 2008

By: Jason Maus, Gerry Wegner Ph.D.

The biology, behavior and control of America’s favorite weather-predicting pest.

The groundhog, Marmota monax (Rodentia: Sciuridae), is one of 14 species of large ground squirrels known as marmots. Adults range in length from 25 to 33 inches (body plus tail) and weigh 9 to 30 lbs. The breeding season extends from early March to late April, following hibernation. A mated pair shares the same den throughout the month-long gestation period, but the male leaves the den prior to the birth of the young in April or May.

One litter is produced annually, usually comprised of two to six young. Young groundhogs are weaned and ready to create their own dens at five to six weeks of age.

Groundhog burrows usually have two to five unsightly entrances, each well-marked by a heap of excavated soil. Burrows may be extensive, with up to 45 feet of tunnels that may reach to 5 feet underground. Groundhog excavations pose a serious threat to agricultural and residential settings – farm machinery that drive over them may be damaged and building foundations may be undermined by them. Furthermore, landscaping and gardens often are ravaged by the excavating and feeding activities of these large rodents.

Whatever your official state animal may be, you might be tempted to substitute it with the groundhog. Whether you call this amazingly cold-hardy wizard a woodchuck, groundhog or whistlepig, there is no denying its survival instincts, as evidenced by vast populations across North America (north of Mexico) in both rural and urban areas.

While many farmers (and homeowners) would rather just shoot these annoying critters than deal with their land damage, the ever-changing laws and regulations are making it increasingly difficult to do so. It seems that groundhogs are aware of this fact: They practically wave to you when you drive by them. It’s almost comical when you see them standing there on their hind legs, watching traffic pass by, all the while munching on clover and grasses.

This is where we, as an industry, come into play. We may not get much business from farmers, but in the suburbs, the game is on!

They’ll wish they saw their shadow…

Depending on the season, prevailing conditions will dictate what we must do to remove these destructive animals from the properties they inhabit. Also, keep in mind that different states have different laws for dealing with these animals.

Imagine how hungry these large rodents are when coming out of hibernation in the late winter or early spring. As a result, springtime is usually the easiest time of year to trap them. Running low on their fat supply, they quickly begin to seek food. Considering that not much of their natural food supply has grown at this point, you don’t have to be too picky about your bait/lure.

Many wildlife management professionals (WMPs) prefer to start off with a fruit like apple, strawberry or cantaloupe. If there is concern over the fruit drying up or spoiling quickly, or infestation by insects, simply soak and store the fruit in some brine (salt water) to help it stay fresh.

In early spring, lawns and fields tend to be wet and a little overgrown from not being mowed all winter. This condition enhances a WMP’s ability to see any travel paths created by resident groundhogs.

By nature, groundhogs will consistently follow the same path to and from its holes to a favorite watering or feeding spot. Within a short period of time, this creates a visible path in the grass or the weeds at the edge of a property line. These pathways make great sites in which to set traps (if you are not concerned with the visibility of a trapped animal).

The trap is set

Depending on their locale, some WMPs prefer to use 36- by 11- by 12-inch live cage traps constructed of 14-gauge wire mesh; these are easy to use and to transfer and combine captured groundhogs, especially the models having a rear panel that opens. Because of the open construction of the wire, the groundhog generally does not see the back of the trap until it runs into it.

One thing to keep in mind when setting traps for groundhogs, however, is to keep the trap level and stable. If the trap moves just a little bit, it will startle the groundhog and result in trap shyness.

The other obvious trap placement site for a groundhog is at its burrow entrance hole. While this may seem like common sense and the easiest way to catch one, there are times when it is not. The authors have personally walked up to a set trap — just in time to see the resident groundhog dive under the traps. Upon closer inspection, it became apparent that a new hole had been dug beneath the traps in order to avoid them.

In this situation, try using a specially designed cage trap that covers the entrance hole — thereby directing the groundhog through the door of the trap. Safeguard makes a good model for this called the Universal Trap. Its design allows you to use it in several different ways, including trapping of raccoons from chimney flues. Again, be sure the trap is level, secure and oriented in the direction of habitual egress.

In addition, consider leaving a couple of non-funneled traps along groundhog activity paths in case they are out foraging when you set the traps. If this doesn’t work, fill in the hole and anticipate its re-opening by positioning the freshly baited Universal Trap directly over it.

And what about just “shooting the varmints”? Well, firearms may be permissible in certain settings and seasons. In some states, WMPs are also permitted to use snares and body-grip traps for groundhogs. Just be sure to check on the legality of your proposed control measures where you operate.

Maus and Wegner are wildlife manager and co-owner, respectively, of Varment Guard Environmental Services, Columbus, Ohio. Contact them at


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