Norway Rats
The rat behind most New York rat calls: big, wary, and living closer to your building than you think.
Where they come from
Not Norway. They come from the steppes of northern China and Mongolia, rode ships into Europe, and reached New York around the time of the Revolution.
Where they thrive
Burrows in soil, tree pits, under slabs and sidewalks. Sewers, subway tracks, basements, trash rooms and anywhere food waste sits overnight.
How they behave
Colony animals that stay within about 150 feet of the burrow and run the same routes every night. Need water daily. Very wary of new objects, so a new station can be ignored for days.
What they eat
Anything people eat, with a taste for protein and grease. A rat eats about an ounce of food a day.
How fast they breed
Mature at about 3 months. A female can have 4 to 7 litters a year of 6 to 12 pups.
Health risk
Leptospirosis from urine, Salmonella, rat bite fever. NYC reported a record number of human leptospirosis cases in 2023.
In New York City
Estimates run up to 3 million. The city hired its first rat czar in 2023 and now requires businesses to put trash in lidded containers.
Did you know?
Their front teeth grow about 5 inches a year, which is why they gnaw through wood, plastic, lead pipe and even soft concrete.
How to tell
| Norway rat | House mouse | |
|---|---|---|
| Body size | 7 to 10 in, plus a tail just as long | 2.5 to 3.5 in, plus a thin tail |
| Droppings | 1/2 to 3/4 in, capsule shaped | 1/8 to 1/4 in, like a grain of rice |
| Fits through | A hole the size of a quarter | A gap the width of a pencil |
| Home range | About 150 ft from the burrow | 10 to 30 ft from the nest |
| Nests in | Ground burrows, sewers, basements | Walls, ceilings, cabinets, boxes |
| New objects | Avoids them for days | Investigates right away |
Rats in New York
- 1700sNorway rats arrive by ship and quickly push out the black rats already here.
- 1860sKit Burns runs rat-baiting fights at Sportsman's Hall on Water Street.
- 2015Pizza Rat drags a slice down subway stairs and becomes the city's mascot.
- 2023NYC names its first rat czar and starts mandatory trash containers for businesses.
5 habits that keep rodents out
- Trash in lidded bins, never bags on the floor overnight
- Doors closed, with sweeps that touch the threshold
- Food and dry goods sealed and 6 inches off the floor
- Clean under and behind equipment every night
- Report droppings or gnaw marks the same day
Related pests
House Mice
Small enough to fit through a pencil-width gap and curious enough to find every crumb in your kitchen.
Read more →German Cockroaches
The roach that lives indoors, breeds fastest, and causes most commercial kitchen infestations.
Read more →American Roaches
The big reddish roach New Yorkers call a palmetto bug, coming up from drains and basements on hot nights.
Read more →Think you have Norway Rats?
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