A groundhog under the deck doesn’t look like much at first: a hole by the footing and a pile of dirt nobody remembers putting there. A year later the patio slab has a crack running through it and the vegetable garden is gone. Groundhogs are one of the most destructive animals a New Jersey homeowner can have in the yard. Most of the damage happens underground, out of sight.
This guide covers how to identify a groundhog problem, the damage burrows cause, what to do in each season, and why “gopher” usually means groundhog in New Jersey.
Signs You Have a Groundhog
Groundhogs, also called woodchucks, are large burrowing rodents, usually somewhere around 5 to 12 pounds. They’re active during the day, mostly early morning and late afternoon, so you have a decent chance of actually seeing one. If you haven’t, these signs point to a groundhog:
- Burrow openings about 10 to 12 inches across, often with a fan-shaped mound of fresh dirt at the main entrance
- More than one hole. A burrow system usually has a main entrance plus one or more escape holes, which can be hidden in brush or under structures
- Holes under decks, sheds, porches, stoops, patio slabs and along fence lines, where the structure gives cover
- Garden damage: vegetables, flowers and young plants eaten down, especially beans, lettuce, squash and clover
- Gnawed wood on deck posts, fences or the base of trees
- Sunken or soft spots in the lawn above tunnels
Burrow systems can run long distances underground with several chambers, so the damage is often far bigger than the holes suggest.
Why Groundhog Burrows Are a Problem
Groundhogs aren’t aggressive toward people, and most of the time they’d rather run than fight. The problem is what they do underground:
- Undermining structures. Burrows under patio slabs, walkways, stoops, sheds and deck footings remove the soil supporting them. Slabs crack and settle, and footings shift.
- Foundation and drainage issues. A burrow along a foundation can channel water toward the basement wall.
- Tripping and mower hazards. Hidden holes and collapsing tunnels in the lawn can turn an ankle or damage equipment.
- Garden losses. A single groundhog can strip a vegetable garden.
- Squatters. Abandoned groundhog burrows get taken over by skunks, foxes and other animals.
Groundhogs can also carry rabies. Never handle one, and keep pets away from burrows.
What Groundhogs Do Through the Year
Timing matters with groundhogs more than with most wildlife, because they’re true hibernators.
| Season | What groundhogs are doing | What it means for you |
|---|---|---|
| Late winter to early spring | Waking up and breeding | Best window to remove a groundhog before babies arrive |
| Spring | Young are born and stay in the burrow | Removal has to account for the young |
| Summer | Feeding heavily, young spread out to dig new burrows | Garden damage peaks; new burrows appear |
| Fall | Fattening up, then going into hibernation as it gets cold | Find and map burrows now; plan exclusion |
| Winter | Hibernating underground | Little activity; the groundhog is still there |
If you find a burrow under the deck in late fall, the groundhog living there is probably settling in for the winter. That’s the time to get an inspection and plan exclusion for when it wakes up, before it has young in spring.
Groundhog or “Gopher”? What’s Really Digging in Your Yard
A lot of New Jersey homeowners call a groundhog a gopher, and that’s fair: both dig. But true pocket gophers don’t live in this part of the country. If you’ve got a large burrow with a mound of dirt at the entrance, especially under a deck, shed or porch slab, it’s almost always a groundhog.
Other diggers leave different signs:
- Moles push up raised ridges across the lawn and small volcano-shaped mounds, without an open hole. See mole control.
- Voles make narrow surface runways through the grass and small holes about the size of a quarter. See vole removal.
- Chipmunks leave small, clean holes about two inches across with no dirt pile.
- Skunks dig shallow, cone-shaped holes in the lawn while looking for grubs.
Not sure which you have? An inspection answers it quickly.
Managing Groundhogs Around Your Home
Make the yard less inviting
- Clear brush, tall grass and woodpiles near the house, which give groundhogs cover.
- Close off the space under decks, sheds and porches once you’re sure nothing is living there.
- Protect gardens with a sturdy fence that extends underground. Groundhogs dig under fences that stop at the surface.
- Don’t fill an active burrow. The groundhog will dig a new entrance, sometimes in a worse spot. Burrows get filled only after the animal is gone.
How professional groundhog control works
- Inspection to find every entrance, map the burrow system and confirm the animal is active
- Humane removal, timed around the season and whether young are present
- Exclusion: wire mesh barriers buried along the base of decks, sheds and slabs, bent outward so groundhogs can’t dig under them. See our repairs and exclusions service.
- Filling and restoring the burrows once the area is clear
New Jersey regulates trapping and relocating wildlife, which is one reason DIY trapping often ends with a groundhog in a cage and nowhere legal to take it. For service details, see groundhog control.
Groundhogs and Other Wildlife
Groundhogs rarely come alone. Raccoons and skunks take over old burrows, and wildlife under decks brings fleas and ticks closer to the house; our flea and tick control guide covers that side. If you’re also hearing something in the attic, read signs you need wildlife removal or our guide to raccoons in the attic.
Groundhog FAQ
Are groundhogs dangerous?
They’re not aggressive, but they can bite if cornered and can carry rabies. The bigger danger is to structures: burrows undermine slabs, steps, deck footings and foundations.
Do groundhogs hibernate in New Jersey?
Yes. They hibernate underground through the cold months, usually waking in late winter. A groundhog under your deck in fall will likely spend the winter there.
Should I fill in a groundhog hole?
Not while it’s active. The groundhog will dig a new exit. Fill burrows only after you’re sure the animal is gone.
How deep do groundhog burrows go?
Burrow systems can run several feet deep and long distances horizontally, with multiple chambers and exits.
What’s the difference between a groundhog and a gopher?
In New Jersey, there isn’t one in practice. Pocket gophers don’t live here, so a “gopher” digging under your shed is almost certainly a groundhog.
Found a groundhog burrow under your deck or shed? Call 201-932-2264 to book an inspection.
