What are groundhogs, and what makes them a problem here?
The groundhog — woodchuck, Marmota monax — is the largest member of the squirrel family in Wisconsin and, pound for pound, the most consequential digger that gets under the state’s rural buildings. An adult runs sixteen to twenty-seven inches nose to tail and five to ten pounds, a stocky, low-slung, grizzled-brown rodent that most people picture standing up on a fence line surveying a hayfield. That posture is charming. What it does underground is not. A woodchuck is an earth-moving machine, and when it decides the sheltered ground under your deck, shed, stoop, or slab is the safest place to build its burrow, it will move a startling volume of soil out from under a structure that depends on that soil to stay level.
Woodchucks are perfectly matched to the landscape around Clintonville: old fields and fence lines, garden plots and crop edges, brushy woodlot margins, and the endless supply of decks, sheds, pole barns, and concrete slabs that give a burrow a solid roof and a hidden entrance. They’re vegetarians and daytime foragers, so unlike a skunk or a raccoon you often see the animal itself — grazing in the yard at mid-morning or late afternoon, then vanishing under the deck. The visible grazing is the nuisance most people notice first. The invisible tunneling under the footing is the problem that costs money.
Because BugBoss does both pest control and wildlife removal, we treat a woodchuck as a complete job — the animal, the burrow, and the buried barrier that keeps the next one from re-digging — rather than trapping the animal and walking away from an open tunnel system under your structure. With woodchucks that distinction is everything, because the burrow is the real damage, and an untended burrow becomes the next animal’s ready-made den.
Wisconsin biology and the burrow cycle
A woodchuck’s whole year is organized around hibernation, and understanding that clock explains the pattern of calls.
Woodchucks are true hibernators — one of the very few Wisconsin mammals that genuinely hibernate rather than just den up for the cold. They go down around October and stay under through March or April, dropping their body temperature and heart rate dramatically and living entirely off the fat they packed on through late summer. This is why late-summer feeding is so aggressive: the animal is eating to survive the winter, not just to get through the day. It emerges in early spring lean, hungry, and ready to breed.
Breeding follows immediately after emergence, in March and April. After about a month’s gestation the female produces one litter a year of two to six young. The young stay in the natal burrow into early summer and typically disperse around mid-July to dig burrows of their own. That mid-summer dispersal is why you’ll sometimes clear a woodchuck from under a deck only to have a young one show up a few weeks later — the juveniles are out looking for their own real estate, and an open, scented burrow under your structure is exactly what they’re shopping for.
The burrow itself is the reason woodchucks matter so much to a building. A single system can run up to five feet deep and sixty feet or more long, with multiple entrances: a main entrance marked by a conspicuous mound of excavated soil, and one or more secondary “spy holes” or plunge entrances dug from the inside as bolt exits, which have little or no soil around them and are easy to overlook. Inside are separate chambers — a nest, and often a dedicated toilet chamber. All of that dirt has to go somewhere, and when the burrow is under a deck footing, a shed skid, a stoop, or the edge of a concrete slab, the excavation removes the compacted soil those elements are bearing on. Over a season or two, that shows up as settling, cracking, tilting stairs, a sagging deck corner, or an eroded slab edge.
Woodchucks are strict herbivores and diurnal — active by day, especially morning and late afternoon. They eat a pound or more of green vegetation a day in season and go straight for garden crops: peas, beans, lettuce, broccoli, carrot tops, young corn, and melons, along with clover, alfalfa, and grasses in the field. They’ll gnaw the bark of fruit trees and ornamentals, and — a genuinely destructive habit on farms and rural properties — they’ll chew through underground power and irrigation lines and the rubber hoses and wiring of parked equipment. They’re also strong climbers and swimmers when they need to be, which surprises people who assume a fence alone will stop them.
When are groundhogs active in Northeast Wisconsin?
Early spring is the wake-up. As woodchucks come out of hibernation in March and April, they’re hungry and breeding, and this is when burrow activity and the first garden damage appear. A burrow that was quiet all winter under your deck suddenly has a fresh mound of dirt beside it.
Late spring and early summer hold the young. From the litter’s birth into early summer, a burrow under a structure may house a mother and several kits, so removal in this window has to account for dependent young rather than sealing them in.
Mid to late summer is dispersal and peak feeding. Juveniles strike out around mid-July to dig their own burrows — so this is when new burrows appear at fresh sites — and every woodchuck is feeding hard to build the fat it needs for hibernation. Garden damage peaks now, and so does the digging.
Fall is the run-up to hibernation: a last push of feeding, then the animals go down around October. A woodchuck that has spent the summer under your slab will hibernate right there, and an undisturbed winter burrow is the seed of next spring’s problem.
Winter is quiet — the animal is hibernating deep in the burrow — but the tunnel system under your structure is still doing its slow damage to the soil, and it’s still an open invitation to other ground-denning animals looking for winter shelter.
Around Clintonville and the surrounding towns, the vulnerability is the combination of gardens, field edges, and structures. Older village homes with decks and stoops, rural properties with sheds and pole barns on grade, and farms with slab floors, granaries, and machine sheds all offer the sheltered, solid-roofed burrow site a woodchuck prefers, and the region’s gardens and crop edges supply the food.
Local den sites
Woodchucks dig where they have a solid roof over the burrow and a hidden entrance, and on properties here the same spots recur. The crawl space under a deck, porch, or stoop is a favorite — the deck is the roof, and the skirt hides the entrance. Sheds and outbuildings on skids, blocks, or slabs are next, with the burrow running under and undermining the floor. On farms, the pole barn, machine shed, granary, corn crib, and old foundation all get burrowed under, sometimes threatening slab floors and footings. Concrete slabs, patios, driveways, and sidewalks get tunneled beneath, which is how you end up with a settling, cracking pad. And out in the yard, brush piles, rock piles, old stone walls, woodpiles, and manure or compost piles serve as natural burrow sites, as do the banks along field edges, ditches, and fence lines.
The giveaway is the entrance with its mound of fanned-out excavated soil, usually six to twelve inches across, at the base of the structure or the edge of the cover — plus, once you look, the mound-less spy holes nearby.
Signs of a groundhog
The signs are big and hard to miss once you know them. The burrow entrance with a mound of excavated dirt is the primary one — a clean, six-to-twelve-inch hole with a fan of soil beside it, at the edge of a deck, shed, slab, brush pile, or field. Look also for the secondary spy holes with little or no soil around them, dug from below as escape exits; finding these is how you learn the burrow is bigger than the one hole suggested.
In the garden and yard, look for whole rows sheared off at ground level, chewed bark on fruit trees and ornamentals (usually low, within the animal’s reach), and worn feeding paths through the vegetation. You’ll often see the animal itself — woodchucks are diurnal, so a stocky brown rodent grazing in the yard mid-morning or late afternoon, or sitting up on its haunches near the burrow, is a common sighting. Fresh soil at an entrance, packed-down runways between the burrow and the feeding area, and, near buildings, settling or cracking in a slab, stoop, or deck footing round out the picture. On a still day you may hear the sharp whistle — the “whistle pig” alarm call — that gives the animal one of its nicknames.
Structural and property risk
The woodchuck’s damage is almost entirely mechanical, and it comes in two forms: what it does to your buildings and what it does to your growing things.
Undermining structures is the serious one. A burrow five feet deep and dozens of feet long, dug under a deck footing, shed skid, stoop, or slab, removes the compacted soil those elements bear on. The result over a season or two is settling, cracking, tilting, and eroded edges — a deck corner that sags, stairs that pull away, a slab that cracks, a shed floor that dips. Burrows dug against a foundation channel surface water down alongside the footing, feeding moisture problems in a basement or crawl space. On farms, burrows under slab floors, feed floors, and granaries threaten the footing and create holes that are a genuine injury hazard to livestock and horses — a leg in a woodchuck hole is a broken leg. And woodchucks gnaw underground utility lines and equipment, chewing power cables, irrigation lines, and the wiring and hoses of parked machinery, which turns a burrow into an electrical or repair problem.
Garden and crop loss is the damage people notice first. A resident woodchuck eating a pound-plus of vegetation a day will strip a home garden fast, and on a larger property it works the crop edges and gnaws fruit trees and ornamentals.
There’s also a downstream risk that’s easy to miss: an abandoned or partly used woodchuck burrow is prime real estate for other animals. Skunks, foxes, opossums, and even raccoons will move into a ready-made burrow rather than dig their own — so a woodchuck problem left alone under your deck frequently becomes a skunk-under-the-deck problem next season. Closing the burrow isn’t just about the woodchuck; it’s about not leaving an open den for whatever comes next.
Woodchucks are a relatively low disease risk to people compared with raccoons or skunks — they’re not a significant rabies vector — but their burrow debris and the parasites (fleas, ticks) they carry are still reasons to keep pets out of an active burrow and to handle cleanup with sense.
Why doesn’t DIY work on groundhogs?
Homeowners try the same short list of woodchuck fixes, and they fail for reasons that trace straight back to how the burrow works.
Filling in the hole is the classic, and it never works on its own. The burrow is a system with multiple entrances, deep tunnels, and a resident animal whose entire skill set is digging — it re-opens a filled hole in a single night, or just switches to a spy hole you didn’t know about. Filling one entrance while the woodchuck lives underneath is, from the animal’s point of view, a minor chore. You have to remove the animal first, then backfill the whole system and block re-excavation with a barrier it can’t dig around.
Repellents and harassment — predator-urine granules, castor-oil products, ultrasonic stakes, blinking lights — wear off, and none of them address the burrow or the food. They might nudge an animal for a day; they don’t move a resident woodchuck out of a good den.
Gas cartridges, smoke bombs, and flooding are the dangerous end of DIY. Gas cartridges and smoke bombs are a real fire hazard used under a deck or against a structure, and they can leave a dead woodchuck decomposing in an inaccessible tunnel under your slab. Flooding a burrow rarely works — the tunnels drain, branch, and rise, and the animal simply retreats to a dry chamber or bolts out a spy hole. All of these also do nothing to keep the next woodchuck from re-digging the same system.
Fencing alone underperforms because woodchucks dig under it and climb over it. An ordinary garden fence set on the surface is something a woodchuck goes beneath in minutes; only a fence buried below grade with an outward lip, and tall enough with a loose or outward-leaning top, actually holds them.
And trapping alone — even done well — leaves the burrow open and the food in place, so you clear one animal and inherit the next disperser in July. There are also handling and relocation rules to follow; woodchucks lost protected status in Wisconsin, so a landowner can remove one on their own property, but how it’s trapped, handled, and released still has to be done correctly.
The BugBoss removal and exclusion process
We handle woodchucks as one complete job, in a deliberate order.
Inspect and map the burrow. We confirm it’s a woodchuck, find the main entrance and every secondary spy hole, and map how far the system runs under the structure — because a job that closes one hole and misses two is no job at all. In late spring and early summer we determine whether young are present, since that changes the timing.
Remove humanely and legally. We remove the animal — and any young — in line with Wisconsin’s nuisance-wildlife rules. Woodchucks aren’t protected, so a landowner has latitude here, but the trapping, handling, and disposition still have to be done correctly, and we do it the way the state requires.
Backfill the burrow. This is the step DIY skips and the reason DIY fails. We collapse and backfill the tunnel system so it can’t simply be re-occupied, restoring support under the footing, skid, or slab that the digging removed.
Seal the void — dig-proof. We close the crawl space or skirt with a buried, L-shaped barrier of heavy galvanized hardware cloth, trenched ten to twelve inches down and bent outward, around the deck, shed, stoop, or slab. A digging animal that tries to re-open the den hits steel below grade and gives up. A lattice panel or surface-laid wire won’t do it; the barrier has to go into the ground.
Address the draws. We advise on and, where it’s our work, handle the food and habitat side — fencing the garden the same dig-proof way, clearing the brush and rock piles that make natural dens, and closing the other open crawl spaces on the property so you’re not just moving the animal next door.
This is core wildlife removal work for us, and because we’re full-service we can address the skunks or raccoons that have moved into an old woodchuck burrow, or the residential pest issues the disturbance kicked up, in the same visit.
The reason we insist on all these steps comes down to how woodchuck problems recur. Trap the animal but leave the open burrow, and a July disperser — or a skunk — moves into the ready-made den within weeks. Fill the hole but skip the removal, and the resident just re-digs it. Remove the animal and backfill but leave the garden unfenced, and you’ve solved the burrow while leaving the buffet that drew the woodchuck there. A woodchuck job that actually holds is the one where the animal is out, the burrow is backfilled, the void is sealed with buried steel, and the food and habitat draws are addressed. Skip any of those and you tend to pay twice.
How do you keep groundhogs out?
Keeping woodchucks out is a two-front job: close the burrow sites and protect the food.
Structures first. Skirt every deck, porch, shed, stoop, and slab with a buried, dig-proof barrier — hardware cloth trenched ten to twelve inches down and bent outward — so the sheltered, solid-roofed den site a woodchuck wants isn’t available. Close gaps at the sill of sheds, pole barns, and outbuildings, and don’t leave the crawl space under any structure open at grade. Fill and screen the eroded edges of slabs, patios, and stoops where a burrow can start.
Habitat next. Woodchucks den in cover, so clear the brush piles, rock piles, old stone walls, woodpiles, and junk-equipment piles that make natural burrow sites near the house, and keep the vegetation down along the immediate perimeter so the animal has no staging cover.
Then the garden. A vegetable garden is a magnet, so protect it with a real fence: buried at least ten to twelve inches with an outward lip, at least three to four feet tall above ground, and either loose or leaning outward at the top so the woodchuck can’t climb over. An electric strand near the top edge helps on persistent properties. None of this evicts a woodchuck already denning under a structure — exclusion is a post-removal and preventive step, not a way to get a resident animal out.
The same buried-barrier work that woodchuck-proofs a deck also shuts out denning skunks and raccoons, so it tends to close the whole ground-level wildlife problem at once. If bats are part of the same project, remember they’re protected in Wisconsin and can’t be excluded during the summer maternity season; we sequence the work so nothing gets sealed at the wrong time.
When should you call BugBoss about groundhogs?
Call as soon as you see the signs — a burrow entrance with a mound of fresh dirt at the edge of a deck, shed, or slab; garden rows sheared off overnight; a stocky brown rodent grazing in the yard by day; or early signs of settling or cracking in a stoop, slab, or deck footing. The sooner a woodchuck is removed and its burrow backfilled, the less soil comes out from under your structure and the less chance a second animal moves into an established den.
In the meantime, don’t try to gas, smoke, or flood the burrow — those methods are ineffective at best and a fire or decomposition hazard at worst — and don’t just fill the hole and hope, because a resident woodchuck re-digs it overnight. Keep pets out of an active burrow. The fastest path to a solved problem is an inspection that maps the whole burrow system and checks for young, followed by removal, a proper backfill, and a dig-proof seal in the right order.
Most pest-only companies serving this area won’t touch wildlife, and most trappers won’t do the backfilling and buried-barrier exclusion that actually keeps woodchucks from re-digging. BugBoss does both, from our base right in Clintonville at 600 S. Main St., so you get removal, a proper backfill, and a dig-proof seal handled together by people you can reach directly. Call 866-BUGBOSS, or request a quote. No long-term contract, no cancellation fee, and you work with Brian, not a call center. We cover the full service area, from Clintonville and Marion to Waupaca, Shawano, and the surrounding rural towns and farms.