Holes Under the Fence: What's Digging In (or Out)?

A hole under a fence is usually a travel gap scraped out by rabbits, skunks, or a neighborhood dog — or the edge of a real burrow if a groundhog has moved in along the fence line. The key distinction is pass-through versus home: a shallow trench under the boards means something is commuting through your yard, while a deep hole with a big dirt pile means something is living there.

Most likely causes

  • Rabbits — smooth 4-inch gaps under the boards with tufts of fur snagged on the wood
  • Groundhogs — a 10-inch burrow entrance with a large dirt mound, often right along the fence
  • Skunks — shallow 4- to 6-inch scrapes, low body clearance, and a faint musky odor
  • Dogs — messy, wide excavations with claw marks and scattered soil on one side
  • Rats — small 2-inch holes at fence posts near sheds, compost, or garbage

Compare the possible causes

Possible cause Key signs When it happens How likely
Rabbits A smooth, worn depression about 4 inches wide under the fence, often with fur caught on the bottom edge and pea-size round droppings nearby Year-round; traffic picks up in spring and summer when gardens are worth visiting Very common
Groundhogs (woodchucks) A burrow entrance 8 to 12 inches across with a substantial mound of excavated dirt, tucked against the fence, a shed, or brush Digging peaks in spring and again in late summer as they fatten for hibernation Common
Skunks A shallow scrape 4 to 6 inches wide and only a few inches deep, sometimes with a lingering musky smell and small cone-shaped holes in the lawn beyond Most active at night, spring through fall; den-seeking intensifies in fall Common
Dogs A wide, messy excavation with obvious claw furrows, soil thrown out in a heap on the digging side, and re-digging in the same spot Any time; often when a dog is left alone, or when something interesting lives on the other side Common
Rats A tight 2-inch hole hugging a fence post or the fence's junction with a shed, with smooth edges and small droppings along the base boards Year-round, concentrated wherever garbage, compost, birdseed, or pet food is nearby Less common

Visual clues to check

  • Measure the gap: 2 inches suggests rats; 4 inches, rabbits or skunks; 8 inches or more with a dirt mound, groundhog; wide and chaotic, dog
  • Check where the dirt went: spread thin means a pass-through; heaped in a fan means a resident burrow; flung in a heap means a dog
  • Look for fur or hair snagged on the fence bottom — rabbit fur is soft and cottony, dog hair is coarser
  • Smell the spot: even a faint skunky odor at the gap is a reliable calling card
  • Scatter flour or smooth the soil at dusk, then read tracks in the morning: paired hopping prints (rabbit), five-toed prints with claw marks (skunk), large canine prints (dog)
  • Follow the hole's direction: a tunnel angling down and away is a burrow; daylight visible straight through is a travel gap

The causes in detail

Rabbits

Cottontails don't dig dens under fences — they scrape just enough clearance to slip beneath and then reuse the same gap nightly, polishing it smooth. The passage is shallow, the soil is spread thin rather than piled, and clipped-off plants at 45-degree angles inside the yard tell you why they keep coming. Block one gap and a rabbit will often test the fence line for another, so check the whole run.

Groundhogs (woodchucks)

A fence line offers cover and an edge to dig along, which makes it prime groundhog real estate. Unlike a pass-through gap, a groundhog hole is a front door: wide, deep, with a fan of subsoil outside and usually a hidden second entrance nearby. Burrow systems run 20 to 40 feet and can undermine fence posts, slabs, and shed foundations, so an established burrow deserves action rather than tolerance.

Skunks

Skunks are surprisingly poor climbers and consummate diggers, so they go under fences rather than over. A skunk pass-under is low and shallow — they have short legs and don't need much clearance. If the digging continues into your lawn as scattered little cone-shaped grubbing holes, the fence gap is just the entry point for a nightly grub buffet. Skunks may also den under sheds and decks on the other side of that fence.

Dogs

Whether it's your dog going out or a neighbor's dog coming in, canine digging is the least subtle option: big paw-fuls of soil flung backward, bite marks on the bottom of wooden boards, and rapid re-excavation after you fill it. The dirt heap sits on whichever side the digger started from, which tells you whose dog to talk about. Escaping dogs are a safety problem worth solving the same week.

Rats

Rats travel fence lines the way we use sidewalks, and a post or rail junction gives their burrow structure and cover. The hole is much smaller than any of the mammals above and shows heavy wear rather than fresh sprawling excavation. Rat sign along a fence usually means a food source within 100 feet or so — find and fix that, and involve a professional if droppings and burrows multiply.

When to worry

  • A 10-inch entrance with a big mound within a few feet of a shed, deck, or slab — groundhog burrows undermine footings
  • Fence posts loosening or leaning near the digging, a sign soil is being hollowed out below the set line
  • A skunk denning (not just passing through) where a dog can corner it — spray is the good outcome; bites need medical attention
  • Rat-size holes multiplying along the fence toward the house, garage, or coop
  • Your own dog getting out — retrieval luck runs out eventually, and traffic doesn't negotiate

What to do now

  1. Identify pass-through versus burrow first: gaps get sealed, burrows need the occupant gone before you close anything
  2. Fill travel gaps and bury an L-shaped skirt of half-inch hardware cloth 6 to 12 inches deep along problem sections, bending the bottom outward
  3. Remove the attraction on your side — unprotected gardens for rabbits, grubs for skunks, garbage and birdseed for rats
  4. For a groundhog burrow, wait until you've confirmed it's unoccupied (loosely plug with newspaper and watch for 3 to 5 days out of hibernation season), then backfill and skirt the fence
  5. For a digging dog, add a dig guard or pour a mow strip along the fence bottom, and address the boredom driving the digging
  6. Call a licensed wildlife control operator for occupied groundhog or skunk burrows — many states restrict relocating both, and skunk eviction is not a DIY perfume risk worth taking

What not to do

  • Don't seal any hole until you're sure nothing is inside — entombing a groundhog or skunk creates a worse problem under your fence
  • Don't reach or shove tools blindly into a burrow; skunks spray and groundhogs bite when cornered
  • Don't use smoke bombs or gas cartridges near fences, sheds, or property lines
  • Don't stack rocks or boards over the gap as a fix — diggers go around or under loose cover in a night
  • Don't let a dog 'sort out' whatever is coming under the fence, especially at night when skunks are active

Think you know the suspect?

These animals commonly cause this clue — see their full sign profiles:

Frequently asked questions

How do I tell if the hole under the fence is a burrow or just a crawl-under?

Look at depth, direction, and dirt. A crawl-under is a shallow trench you can see daylight through, with soil spread thin. A burrow angles steeply downward, keeps going beyond arm's length, and has a distinct mound of excavated dirt outside the entrance. Burrows mean a resident; trenches mean a commuter.

What size hole does a groundhog make under a fence?

A groundhog's main entrance is typically 8 to 12 inches across — noticeably bigger than anything a rabbit, skunk, or rat leaves — with a large fan of dirt and packed-down soil from daily use. There's usually at least one plainer secondary hole within 25 feet or so that lacks the big mound.

Will filling the hole with dirt stop the animal?

Rarely by itself. A commuting rabbit or skunk re-scrapes a soft-filled gap in one night, and a resident groundhog digs out in hours. Fill works only when paired with a physical barrier — buried hardware cloth bent outward in an L — and, for burrows, only after the occupant has verifiably left.

How deep should I bury wire to stop digging under a fence?

Six to twelve inches down, with the bottom of the mesh bent 90 degrees outward (away from your yard) for another 6 to 12 inches. Diggers work at the fence face, hit wire, step back onto the buried flange, and give up. Half-inch or quarter-inch hardware cloth outlasts chicken wire by years.

Related yard clues

Yard Holes Large Holes in Yard: Groundhog, Fox, Skunk, or Armadillo? A hole 6 inches across or bigger is a den entrance, and in most American yards the owner is a groundhog — an 8- to 12-inch hole with a big dirt mound is their signature. Foxes, armadillos, and skunks dig or borrow similar burrows, especially under sheds, decks, and porches, so smell, mound size, and location are what separate them. Never fill a large hole until you know it's empty. Read the guide → Yard Holes Holes Near Your Foundation: Causes and When to Act Holes right along a foundation usually come from chipmunks, Norway rats, or voles, all of which like the shelter a house wall provides — but water pouring from downspouts and settling backfill soil carve foundation-line holes too. Sorting burrow from washout matters, because a rat burrow against the house is the one that needs fast professional attention. Read the guide → Yard Holes Two-Inch Holes in Yard: Chipmunk, Rat, or Something Else? A round hole about two inches across is classic burrow size, and the usual suspects are chipmunks, rats, and thirteen-lined ground squirrels. Chipmunk holes are clean with no soil pile, rat holes are worn and hug structures, and ground squirrel holes sit in open, sunny lawn — those three clues sort out most cases. Read the guide →

Still not sure? Compare with these clues

Tracks, Nests & Outdoor Clues Small Animal Tracks in Your Yard: How to Read Them Small animal tracks in your yard most often belong to rabbits, squirrels, raccoons, opossums, skunks, or a neighborhood cat or dog. Counting the toes, checking whether claw marks show, and looking at how the prints are grouped will identify the visitor faster than the shape of any single print. Read the guide → Animal Droppings Droppings Under Your Deck: What Animal Is Denning There? Droppings under a deck usually mean an animal is using the space as a den, not just passing through — most often a skunk, opossum, feral cat, or raccoon, and occasionally a groundhog. Skunk droppings are crumbly and full of shiny insect parts, opossum droppings are large and curved, cat droppings are often buried in loose soil, and a pile of tubular droppings in one corner is a raccoon latrine that needs professional-level caution. Timing matters: from spring into midsummer, most of these animals have babies down there. Read the guide → Yard Holes Holes in Flower Beds Overnight? Meet the Night Shift Flower beds dug up overnight are almost always animals hunting food, not making homes: skunks and raccoons dig for grubs and worms in the soft soil, squirrels bury and retrieve nuts, cats use loose beds as litter boxes, and across the South armadillos root through beds nose-first. Each leaves a different style of hole, so one careful morning inspection usually names your visitor. Read the guide →