The Quick Answer
The sounds, smell, digging, and droppings under your deck or shed tell you who moved in before you ever see it: scratching-plus-thumping usually means armadillo; a strong musky smell and grease marks mean skunk or raccoon; a clean, hidden hole with tunnels means gopher or pocket gopher; and flattened grass with tunnels along the base means groundhog, rat, or rabbit. Here's how to tell each apart and get them to leave safely.
First 10 Steps Before You Commit to Removal
Whatever is under there, do not reach in, shine a light in a tunnel mouth while your hand is near it, or seal the opening without confirming it's empty. A mother and young being trapped inside creates a much bigger emergency. Start with these basics:
- Note active times: daytime means groundhog, gopher, rabbit, or squirrel; dusk/night means armadillo, skunk, raccoon, or opossum.
- Release a little flour at the opening and check for fresh tracks the next morning.
- Set a camera or check for fresh digging, smell, and droppings daily for two or three days before acting.
1. Armadillo — Digging a Burrow Under the Deck
Armadillos dig 6- to 8-inch-wide tunnels that go back several feet, often following the edge of a deck or shed slab. The entrance is a round, clean hole with freshly pushed dirt.
Signs: The classic cone-shaped diggings in the lawn nearby (it feeds within a few yards and then retreats under the deck), fresh soil mound at the den mouth, and activity just after dusk and before dawn.
Behavior: A single armadillo typically uses several resting burrows and may only be denning under your deck during rough weather. They bolt fast when startled.
What to do: Remove the grubs it feeds on and dry out the soil; cap the burrow only after confirming it's empty by plugging the mouth with soil and watching for re-excavation. Under-deck gaps can be fenced with a few inches of buried lattice or hardwire cloth.
2. Skunk — The Musky Odor Tell
A faint skunk musk that gets much stronger around dusk is the clearest sign. Skunks dig a shallow burrow, often reusing an armadillo hole, and leave 1- to 1.5-inch diggings in the lawn.
Signs: Strong odor near the opening, small lawn pits, five-toed tracks with long front claws, and activity at night.
What to do: Skunks are placid unless cornered, but a startled one sprays — so never block a skunk hole from the outside during the day when it's denned inside. Do exclusion only after confirming it has left at night. If you smell spray, you're too close; back off and get a pro.
3. Raccoon — A Latrine and Grease Marks
Raccoons under a deck often make a latrine (a pile of scat in one corner), and the wood around the access shows dark grease from their fur squeezing through.
Signs: Chittering and heavy thumping at night, a smelly scat latrine, grease smears on supports, and an entry gap at least 3–4 inches.
What to do: Raccoons are strong and persistent. Clear the entry only after confirming no kits are present (listen for whining at night), then seal with hardware cloth. Do this at dusk when the adult is out foraging, and watch for a return attempt.
4. Opossum — Low-Risk Transient
Opossums rarely dig; they use existing openings. They leave no musky smell, no latrine piles, and no noise, but you may find scattered pointed scat and a slightly musty den.
Signs: Five-toed tracks with the inward-pointing "thumb," pointed grey scat in the corners, and an animal that plays dead when startled.
What to do: The lowest-stakes resident. Remove food and water sources, and block the opening at night after it leaves. It won't fight you structurally the way a raccoon will.
5. Groundhog (Woodchuck) / Pocket Gopher — Tunnels and Mounds
Two digging types dominate under sheds and along foundations and both are diurnal (daytime).
Groundhog: A more prominent entrance mound, often at the very base of a shed, with a main tunnel going deep and two or more exit holes. Droppings are oval and blunt. Activity is in the morning and late afternoon.
Pocket gopher: A fan-shaped soil mound with no visible opening (gophers plug their tunnel mouths) and ridged tunnels just under the sod. The "pocket" is the cheek pouches. They push soil in characteristic crescent fans.
What to do: Both undermine foundations and slabs, so don't ignore them. Confirm the tunnels are empty before sealing, because a gopher will dig around most simple plugs. A pro under-slab exclusion is often the only permanent fix for a groundhog under a foundation line.
6. Rats — The Hidden, Persistent Resident
A rat under a shed is the one you may never see during the day. You'll notice grease rubs along the edges, small pointed droppings (roof rat) or larger (Norway rat), tunnels along the baseboard or foundation, and gnawed wood.
What to do: Rats need exclusion at every gap larger than 1/4 inch, plus food removal. This is a multi-night project: seal gaps, set traps far from entrances, and monitor. Rats are the highest reproduction risk of the group — a pair can multiply quickly under a shed — so act on the first evidence.
Comparison Table
| Animal | Active Time | Opening Size | Smell | Droppings | Main Tell |
|---|---|---|---|---|---|
| Armadillo | Dusk/Dawn | 6–8 in round | None | None at den | Fresh soil mound + lawn coning |
| Skunk | Night | 4–6 in | Musky | Small, blunt | Odor picked up at dusk |
| Raccoon | Night | 3–4+ in gap | Strong if latrine | Tubular latrine pile | Grease marks + thumping |
| Opossum | Night | 3+ in gap | Mildly musty | Pointed, grey | Splayed "thumb" track |
| Groundhog | Day | Entrance mound at base | None | Oval, blunt | Crescent soil mound, 2+ exits |
| Pocket gopher | Day | Plugged, fan mound | None | Underground | Crescent fan, no visible hole |
| Rat | Night | >1/4 in gap | Dank | Pointed pellets along walls | Grease rubs + gnawed wood |
How to Remove Safely — The Correct Sequence
Confirm empty. Plug the opening loosely with crumpled newspaper or soil. If it stays plugged 48–72 hours, the den is empty enough to seal. If it's disturbed, an animal is inside — back off.
Remove food. Clear pet food, garbage, compost, and fallen fruit. Most of these animals stay because of food, not shelter.
Seal at the right time. Exclude nocturnal animals at dusk when they leave; exclude diurnal (groundhog, gopher) during midday when they're out. Seal with buried hardware cloth or a solid frame — never with a light wire they can push.
Watch for reentry. Leave a camera or a soil-flour patch for a few nights after sealing.
An animal is already denning under your deck or shed and has young you can't confirm are out? Don't seal it blind. A licensed pro can safely exclude without trapping a family inside. Compare free quotes near you.
Frequently Asked Questions
How do I know if a burrow under my shed is empty?
Loosely plug the entrance with crumpled newspaper or soil and wait 48–72 hours. If it stays undisturbed, it's safe to seal. If it's moved, an animal is inside — wait and recheck, or call a pro.
Is it a groundhog or a gopher under my shed?
Groundhogs leave a visible crater-mound entrance with two or more exit holes and are active during the day. Pocket gophers push crescent fan-shaped mounds with no visible opening because they plug their tunnel mouths.
What smells like skunk under my deck but I can't see it?
That's almost certainly a striped skunk denning during the day. The odor is strongest at dusk. Never block a skunk hole during the day when it's inside — wait until it leaves at night.