Norway rats in Austin, the rat that digs under your slab

What is a Norway rat, and how is it different from a roof rat?

A Norway rat is the heavier rat that digs, and the roof rat is the slimmer one that climbs better. UC IPM calls the Norway rat a burrowing rodent, usually bigger and stockier than the roof rat. The card below shows you the four spots to check.

Look-alikes

Norway rat or roof rat?

1 2 3 4

Norway ratAlso called the brown rat

vs

1 2 3 4

Roof ratAlso called the black rat

How to tell an adult Norway rat from an adult roof rat

Look at	Norway rat	Roof rat
1Nose	Blunt	Pointed
2Ears	Folded over, they don't reach the eyes	Long enough to reach the eyes when folded over
3Tail	Shorter than the body, dark on top and pale below. Pulled over the back, it reaches the middle of the skull	Longer than the body and dark all over. Pulled over the back, it reaches at least the snout
4Body	Large and robust, 7 to 18 ounces	Sleek, 5 to 10 ounces

Got a dead one? Pull the tail over its back. A roof rat's reaches at least the snout, a Norway rat's only the middle of the skull. Never on a live one. In a photo, compare the tail with the head and body.

The nest helps too. Up high, you've usually got a roof rat, Texas A&M says, and underground it's almost always a Norway rat.

Rather watch? A New Zealand wildlife biologist shows the tail and ear checks in under two minutes. There, the roof rat's a ship rat.

Not sure which rodent you've got?

Tell us what you found, and you'll get our best guess and whether it's worth a call.

Which one is it?

Which rodent is it?

Pick what you found for our best guess, and whether it's worth a call.

See every answer

Probably a Norway rat Worth a call

Texas A&M says a nest underground is almost always a Norway rat. Don't pour bait down the hole. Store-bought bait comes in stations, the EPA says. See rodent control

Maybe an old burrow Keep an eye on it

Active holes are clean and clear of debris, ICWDM says. One full of leaves may not be in use. Check back for fresh dirt.

Probably a roof rat Worth a call

Texas A&M says a nest up high is usually a roof rat, and roof rats seldom burrow. Norway rats can climb too, so check the tail and ears against the card above. Read the roof rat guide

Maybe a house mouse Seal and trap

Norway rat droppings can be up to 3/4 inch long, ICWDM says. If yours are a lot smaller, it may be a mouse. See how mice get in

Probably not a rat Check what's digging

A Norway rat burrow has an open main hole, about 2 to 4 inches across, Pests in the Home says. A closed mound doesn't match. See what makes dirt piles

What does a Norway rat burrow look like?

You're looking for a round hole about 2 to 4 inches across, worn smooth, often with fresh dirt fanned out in front. That's the main door, Pests in the Home says, though it can look different by region. There are usually 1 or 2 others you may not notice. And the site puts the tunnels no deeper than 18 inches.

Their burrows may turn up along foundations, under rubbish or woodpiles and around gardens, UC IPM says, and that digging can undermine foundations and slabs. Texas Tech's mammal guide adds burrows under sidewalks and outbuildings, like your shed.

To tell if a hole's in use, check for these:

• A clean hole. Active holes are clear of debris, with rat hairs around the entrance, ICWDM says.
• Worn paths. Rats use the same routes, so check along your walls, fences and under bushes.
• Greasy rub marks. You may see smudges on walls and pipes, from the oil and dirt on their fur.
• Blunt droppings. Up to 3/4 inch long with blunt ends, usually in small clumps.

Dirt mounds with no open hole are probably something else, and our dirt piles guide covers those.

Are there Norway rats in Austin?

Yes, but you'll probably run into roof rats more. Texas Tech says the Norway rat is widespread in Texas but less common than the roof rat in the state's southern half.

Our own count of Travis County iNaturalist photos agrees. In Travis County, people posted about 6 roof rats for every Norway rat, and Texas looks the same. Across the US, it flips: almost 2 Norway rats per roof rat.

Around Austin, most rats people photograph are roof rats

Our count of research-grade iNaturalist photos of the two rats: the share that are Norway rats (orange) and roof rats (gray).

• Norway rat
• Roof rat

It counts photos, not rats. You'll spot a roof rat on a fence a lot easier than a Norway rat in its burrow. And it's small: just 14 Norway rat photos here.

Texas A&M's pest course says wild Norway rats live near woods and streams and commonly follow creeks, ditches and sewers to new areas. Bird feeders, pet bowls, weeds and messy compost bins favor them too, it says.

Can Norway rats make you sick?

Rats can carry flea-borne typhus, but Austin's 2008 study tested too few rats to judge. The Texas health department says rats and their fleas are its natural reservoir. Opossums and pet cats may spread it too, and fleas are the usual carriers.

In Austin's 2008 outbreak, CDC and Texas researchers found antibodies in 12 of 17 opossums, 4 of 9 dogs and 3 of 17 cats near patients' homes. They say that suggests opossums and pets may be part of the cycle. The 4 rats tested were negative, too few to judge, the authors said. Our roof rat guide charts the local cases by year.

How do you get rid of Norway rats?

Seal them out at ground level, then trap or bait the rest. Texas A&M's rat guide calls rat-proofing the most permanent fix, if the cost is reasonable: metal over edges they could gnaw, concrete to stop burrowing under your foundation.

UC IPM says to seal every hole bigger than 1/4 inch, so you keep out mice too. Here's how mice get in. Then:

• Treat fleas first. Do it before rodent control, the Texas health department says, or the fleas leave the dead rats for new hosts, possibly you.
• Seal before you bait outside. That way poisoned rats don't come inside to die, UC IPM says.
• Put stations by the burrows. Or against walls and along their paths. Rats might take days to weeks to use them.

Can you handle Norway rats yourself?

Some of it, sure. Take in your feeders and pet bowls, clear the clutter, seal with metal or concrete, and set traps. Pros, the EPA says, have to keep bait in tamper-resistant stations anywhere kids under 6, pets or wildlife can reach.

That's how our rodent control works. Plans cover 40+ pests, rodents included, from $66 a month, with sealed, tamper-resistant stations checked every visit. That lowers the risk, but it doesn't remove it. An active infestation is a separate job from $449, and sealing's quoted on top once we see your house. See our services and cost guide.

Common questions