How do I know if it's rats or mice in my NYC apartment?

Size is the giveaway. Rat droppings are large (about 1/2 to 3/4 inch) with blunt, capsule-like ends, while mouse droppings are tiny (under 1/4 inch) with pointed ends, like dark grains of rice. Rats also leave greasy rub marks and finger-width gnaw holes; mice leave smaller, cleaner damage. If you're unsure, our guide to getting rid of mice in a NYC apartment covers the mouse side in detail.

What do rat droppings look like?

NYC's Norway rat leaves dark brown to black droppings roughly 1/2 to 3/4 inch long, shaped like a fat capsule or a tiny banana with blunt, rounded ends. They're often scattered along walls, under sinks, behind appliances and in cabinets rather than piled in one spot. Fresh droppings are dark, soft and shiny; old ones turn gray, dry and crumbly.

Why do I hear scratching in my walls at night but never see a rat?

Rats are nocturnal and most active from about an hour after dusk until just before dawn, so you'll hear scratching, gnawing and scurrying in walls, ceilings and airshafts at night while the rat itself stays hidden. In NYC buildings they travel inside wall voids, between joists and up plumbing chases, which is why the noise moves around. Hearing it is a reliable sign of activity even without a sighting.

Are rat droppings in my apartment dangerous?

Yes — treat them as a health hazard. Rats and their urine can spread leptospirosis, which the NYC Health Department links almost entirely to rat exposure; the city recorded 24 human cases in 2023, its highest on record. Don't sweep or vacuum dry droppings, which can aerosolize germs. Ventilate, wear gloves, dampen the area with disinfectant, wipe up, and bag the waste.

What does a rat burrow look like, and where are they in NYC?

A Norway rat burrow is a smooth, clean hole about 2 to 4 inches across, often with loose dirt fanned out at the entrance and a second 'bolt hole' exit nearby. In NYC you'll find them against building foundations, under sheds and decks, in tree pits and planters, along basement walls, and next to trash storage and dumpster areas. Active burrows are free of cobwebs and debris.

How many rats are in my building if I see one?

One visible rat usually means more, because rats are nocturnal and hide — seeing one during the day often signals a larger colony being crowded out. NYC Norway rats live in colonies and rarely travel more than about 300 feet from their burrow, so a daytime sighting points to a nearby, established nest, frequently in a shared basement, airshaft or trash area serving the whole building.

Should I report rats in my NYC building?

Yes. You can report a rat problem to NYC 311, which routes it to the Health Department; the city receives roughly 40,000 rat complaints and runs over 150,000 inspections a year. If you rent, also notify your landlord in writing, since under NYC's Housing Maintenance Code the owner is generally responsible for keeping the unit free of rats. See our guide on landlord vs. tenant pest responsibility.

How fast can a few rats become an infestation?

Quickly. A single female Norway rat can produce multiple litters a year with several pups each, so a small problem in a food-rich NYC building can grow within weeks. That's why acting on the first signs — droppings, gnawing, rub marks — matters far more than waiting for a sighting. Sealing entry points and knocking down the population early is the cheapest way to stop it.

Signs of Rats in Your NYC Home: How to Tell If You Have a Rat Infestation

How to tell if you have rats

If you suspect rats in your NYC home, look for seven things: large capsule-shaped droppings, gnaw marks, greasy rub marks, scratching at night, burrows, a musky ammonia odor, and live sightings. In New York, the culprit is almost always the Norway rat (the brown rat) — a ground-dwelling, nocturnal animal that nests in burrows, basements and subterranean infrastructure and rarely strays more than about 300 feet from its nest (Wikipedia, Rats in New York City). Because they move at night and stay hidden, you’ll almost always find the evidence before you find the rat. Here’s exactly what to look for.

The NYC Health Department receives about 40,000 rat complaints through 311 each year and conducts over 150,000 rat inspections annually (NYC Environment & Health Data Portal) — so if you’re seeing signs, you are far from alone. Catching it early is the difference between a quick knockdown and a building-wide problem.

1. Droppings — the single most reliable sign

Droppings are the clearest evidence of an active rat problem. NYC’s Norway rat leaves droppings that are roughly 1/2 to 3/4 inch (12–18 mm) long, dark brown to black, with blunt, rounded, capsule-like ends — often described as looking like a fat grain of rice or a tiny banana (Orkin). This is the easiest way to separate rats from mice: mouse droppings are tiny (3–6 mm) with pointed, tapered ends, like dark specks of rice.

A few things to read from droppings:

Where they are. Rats scatter droppings along their travel routes — against baseboards, under kitchen sinks, behind the stove and fridge, inside lower cabinets and drawers, and in basements and utility closets.
How fresh. Fresh droppings are dark, soft and shiny; older ones fade to gray, dry out and crumble. Fresh droppings in multiple spots mean an active, current infestation.
How many. A single rat can leave dozens of droppings a night, so a heavy scatter points to either a long-running problem or several animals.

Do not sweep or vacuum dry droppings. This can stir up particles you don’t want to breathe (more on the health risks below). For the full cleanup-and-control sequence, see how to get rid of rats in NYC.

2. Gnaw marks on wood, wiring and packaging

Rats’ incisors never stop growing, so they gnaw constantly to wear them down. In a NYC apartment or brownstone, look for:

Fresh, light-colored gnaw marks on baseboards, door corners, cabinet edges and wooden trim (fresh chewing is pale; old marks darken with grime).
Coin-sized or larger holes chewed through drywall, around pipe penetrations, or at the base of doors. Rats can enlarge a gap the size of a quarter into a doorway.
Chewed food packaging in pantries and cabinets — torn bags of rice, flour, pet food and cereal.
Gnawed electrical wiring, a genuine fire hazard and a classic reason rats turn up in DOH and electrical inspections.

Rat gnaw marks are noticeably larger and rougher than the fine, clean nibbling of mice.

3. Greasy rub marks and runways

This is the sign most people miss — and it’s one of the most telling. Rats have poor eyesight, so they navigate by touch along walls and fixed surfaces, running the same routes over and over. The oil and dirt in their fur leaves a dark, greasy smudge — a “rub mark” or “smear” — along baseboards, around pipe and beam corners, along the edges of stairs, and at the lip of holes they squeeze through (Western Exterminator).

In NYC homes, check:

The base of walls in basements, cellars and utility rooms.
Pipe risers and plumbing chases where rats climb between floors.
The edges of airshaft and vent openings, and gaps around radiator pipes.
Along runways — narrow, worn, debris-free paths through dust, soil or cluttered storage where rats travel repeatedly.

Greasy rub marks at the corner of a hole are near-proof that rats — not mice — are using it.

4. Scratching and scurrying at night

Norway rats are nocturnal, most active from about an hour after dusk until just before dawn (Anderson Pest Solutions). That’s why so many New Yorkers report the same thing: noise in the walls at night, but never a rat in sight.

Listen for scratching, gnawing, squeaking and scurrying inside walls, ceilings, airshafts and above drop ceilings after the apartment goes quiet. In NYC’s attached buildings, rats travel through shared wall voids, between floor joists and up plumbing chases, so the sound seems to move around. Hearing this consistently at night is a reliable indicator of activity even with zero sightings.

5. Burrows — outside and in the basement

Norway rats are burrowers. A burrow entrance is a smooth, clean hole about 2 to 4 inches in diameter, often with loose excavated dirt fanned out at the mouth and one or more nearby “bolt holes” (escape exits). An active burrow is free of leaves, cobwebs and debris; an abandoned one fills in.

In NYC, the prime burrow spots are:

Against building foundations, basement walls and below-grade entries.
Under stoops, decks, sheds and ground-floor extensions.
In tree pits, planters, garden beds and overgrown yards.
Right next to trash storage, dumpster corrals and bagged-garbage piles — the single biggest rat magnet in the city.

Burrows clustered near your trash area or foundation mean the colony is established close to the building. NYC’s sewers, subway tunnels and connected basements give rats enormous additional harborage (Wikipedia, Rats in New York City), which is why a yard or basement burrow problem so often becomes an indoor one.

6. A musky, ammonia-like odor

A heavy infestation produces a persistent musky, ammonia-like smell from rat urine and from grease and droppings building up in nesting areas — wall voids, behind appliances, in cluttered basements and storage. A sudden foul, decaying odor inside a wall or ceiling can also mean a rat has died in an inaccessible space. If a room smells musky with no obvious source, it’s worth investigating for the other signs above.

7. Live sightings — and what they really mean

Because rats are nocturnal and shy, seeing one in daylight often signals a larger colony — competition is pushing some animals out into the open to find food. A live rat in your apartment, hallway, basement or yard, especially during the day, points to an established nest nearby. Since NYC Norway rats rarely range more than ~300 feet from their burrow, a daytime sighting usually means the nest is close — frequently in a shared basement, airshaft or trash area serving the whole building.

Why rat signs are a health issue, not just a nuisance

Rat evidence isn’t only unpleasant — it carries real health risk. Rats and their urine can transmit leptospirosis, a bacterial infection the NYC Health Department links almost entirely to rat exposure. The city recorded 24 human leptospirosis cases in 2023 — its highest in a single year — up sharply from an average of about 3 cases a year in the early 2000s (NYC Health). Rats can also contaminate food and surfaces and trigger asthma and allergy reactions. This is why you should never dry-sweep or vacuum droppings: dampen the area, wear gloves, disinfect, wipe and bag.

What to do once you’ve confirmed the signs

Spotting the signs early is the win. In NYC, the lasting fix is always the same two-part approach: exclusion plus knockdown. Seal every entry point larger than a quarter — around pipes, foundation cracks, vents and door sweeps — then remove the active population with trapping and tamper-resistant baiting. Killing rats without sealing how they get in just invites the next wave, because the city’s connected basements, sewers and trash supply never stop feeding them.

If you rent, report the problem to your landlord in writing and to NYC 311 — under the NYC Housing Maintenance Code the building owner is generally responsible for keeping your unit free of rats (see landlord vs. tenant pest responsibility in NYC). For multi-unit buildings, evidence in several apartments means the source is shared and needs a building-wide response.

When droppings show up in more than one room, you hear consistent night activity, or you find burrows near the foundation, the source is usually beyond a single unit. Our rat & mouse control service inspects the whole building envelope, finds and seals the entry points DIY misses, and knocks the population down across the building and the block — not just the one apartment. If you want to budget first, see what a rat exterminator costs in NYC, or go straight to a building-aware fix with our rodent control program.