Rat Burrow by the Slab or Seawall? How to Tell Norway Rats From Roof Rats

A round hole about 3 inches across, with freshly dug dirt fanned out in front of it and a worn path leading in, is the classic sign of a Norway rat burrow. When you find one tucked against a patio slab, along a foundation wall, in the soil behind a seawall or canal bank, or under stored lumber near the garbage area, it points more toward a Norway rat than a roof rat. Norway rats live and nest at ground level, while roof rats usually nest up high.

The clue is a strong one, but it isn’t certain. Roof rats sometimes dig when they can’t find a good high nesting spot, and several other South Florida animals make holes in yards. Leave the hole as it is for now. Don’t reach in, fill it, or put smoke or gas into it. Note where it is, then check the other clues below.

What does a Norway rat burrow look like?

Norway rats dig for shelter and nesting. They favor soil banks, the edges of walls and slabs, and the ground under piles of rubbish, wood or other stored material. A typical burrow has:

• an opening around 3 inches wide
• loose, freshly dug dirt scattered in front of it
• a path 2 to 3 inches wide leading to the opening, often smooth and packed down under plants or along a wall
• sometimes a second or third opening nearby, since a burrow system usually has an escape hole as well as a main entrance

Burrows usually run about 18 inches deep, so what you see at the surface is a small part of the system. A slick, hard-packed path suggests rats have been using the spot for a while. Fresh dirt that keeps reappearing after you’ve noted it means the burrow is in use.

In Florida, roof rats are the more common rat across most of the state, and Norway rats are less widespread. Where Norway rats do show up, they tend to be near the coast, along canals and around garbage that isn’t stored tightly. They are also strong swimmers, so a burrow in the bank behind a seawall or along a canal edge fits that pattern better than one in the middle of a dry inland lawn.

A burrow right against a building is worth watching, because over time digging can undermine slabs, foundations and soil banks.

Norway rat or roof rat: the clues at ground level

You may never get a good look at the animal. Both rats are mostly active at night, and a quick glimpse rarely shows the ears or tail clearly. Where you find the evidence, and what the droppings look like, often tell you more.

Clue by clue, the two compare like this:

• Where it’s most active
  • Norway rat: ground level, such as slabs, foundations, banks and garages
  • Roof rat: up high, such as trees, palms, rooflines and attics
• Nesting
  • Norway rat: burrows in soil, under slabs and under stored material
  • Roof rat: nests above ground and digs only now and then
• Body and face
  • Norway rat: heavy-set, gray to reddish-brown, with a blunt muzzle
  • Roof rat: slender, with sleek dark fur and a pointed face
• Ears
  • Norway rat: small, and don’t reach the eyes when folded forward
  • Roof rat: large, and reach the eyes when folded forward
• Tail
  • Norway rat: shorter than, or about equal to, the head and body
  • Roof rat: longer than the head and body
• Droppings
  • Norway rat: about 3/4 inch, capsule-shaped with blunt ends
  • Roof rat: up to about 1/2 inch, pointed at the ends
• Inside the home
  • Norway rat: garage, ground floor and lower walls
  • Roof rat: attic, upper walls and ceilings

If most of what you’re finding is overhead, such as scratching above the ceiling or droppings in the attic, roof rats are the likelier match, and our guide to roof rat signs covers that side. A single burrow or a few droppings are rarely enough to be sure either way. Several clues pointing the same way are more reliable.

Could another animal have dug the hole?

Before deciding it’s a rat, rule out the common lookalikes.

• Land crabs live in low-lying coastal areas, rarely more than about 5 miles from the shore. Their burrows are about 3 to 5 inches wide and can go down several feet, deep enough to reach water.
• Holes smaller than about 3 inches can be made by insects, moles, rodents or snakes. Don’t put a hand or foot into any hole when you can’t see the bottom.
• Holes 6 to 12 inches wide at the base of a tree, log or wall usually belong to a larger animal such as an armadillo, fox, skunk or coyote.
• A gopher tortoise burrow is wide and flat along the bottom, shaped a bit like the tortoise’s shell, often with a mound of sand at the mouth. Gopher tortoises and their burrows are protected under Florida law, so leave them alone.

To check for rat traffic without disturbing anything, dust a thin layer of talcum powder on the path just outside the opening, not into the hole, and look the next morning. Rat tracks show 5 toes on the hind feet and 4 on the front, and you may see a line where the tail dragged.

What to do after you find a burrow

1. Leave it undisturbed and keep children and pets away. Photograph it with something in the frame for scale, and note where it sits in relation to the slab, wall, seawall or bins.
2. Check the nearest part of the building. Look at the bottom of the garage door, the joint where the slab meets the wall, and the places where pipes and utility lines go in. A rat can get under a door with a gap of about 1/2 inch.
3. Take away food and cover. Keep garbage in containers with tight lids and don’t leave bags out overnight. Bring pet food in at night, pick up fallen fruit, and clear piles of wood, debris and deep mulch near the house.
4. Check again in a day or two. Fresh dirt, a new opening or tracks in the powder mean the burrow is active.

Two common reactions can make things worse. Smoke and gas cartridges aren’t recommended near homes, because a burrow can run under the house with several openings, fumes can get inside, and there’s a fire risk. Loose rat poison is toxic to pets, children and wildlife, and a poisoned rat can crawl into the house and die where you can’t reach it.

If you find droppings in the garage or a shed, don’t sweep or vacuum them. Put on rubber or plastic gloves, spray the droppings with a disinfectant until they’re very wet, wait about 5 minutes, then wipe them up with paper towels.

When a burrow needs a professional look

It makes sense to have the burrow inspected when:

• it sits against the slab, foundation, patio or a bank you need to stay stable
• fresh dirt keeps coming back, or new openings appear
• you find droppings, gnawing or rub marks (dark, greasy smudges along a wall) in the garage or on the ground floor
• you see rats in daylight, which can point to a larger population
• there are burrows under a shed, deck or stored material close to the house

A useful inspection follows the burrows to where they lead and checks where the building could let rats in. Before you approve any work, it’s fair to ask:

• Which kind of rat do the signs point to, and why?
• Where are the active burrows, and are any close to the slab or foundation?
• Which openings in the building need closing, and when does that happen relative to trapping or baiting? Our article on what rodent exclusion usually includes explains what that sealing work tends to cover.
• How will any bait or traps be kept away from pets and children?
• What follow-up is planned, and what should you watch for in between?

Getting a burrow checked

Pest Busterzz rodent control starts with an inspection of entry points, nesting areas and signs of activity around the property. If you’ve found a burrow by your slab, seawall or garbage area, you can request an inspection and mention where the burrow is and how long you’ve been seeing fresh dirt. If you took photos, have them handy.