Brown rat: spotting the Norway rat and its runs
It lives below street level, keeps to the same routes and distrusts anything new.
Guide 01
Rattus norvegicus
Key points
The brown rat (Rattus norvegicus), also called the Norway rat, is 20 to 28 cm long without its tail. It lives at ground level and below: cellars, courtyards, sewers, crawl spaces. Its urine can spread leptospirosis and it gnaws through cables. We control it with tamper-resistant bait stations, then seal the gaps it uses.
The brown rat is a network animal. It climbs up from the sewers through pipes, comes out of a poorly covered vent or duct, and digs burrows in courtyards and green spaces. A hole the size of a coin is enough to let it in.
Wary of new objects, it often ignores a trap or bait for the first few days. So before placing anything, we map its regular runs, water points and food sources: that is where the treatment has to go.
Spotting signs of brown rats
- 1Spindle-shaped droppings, 1–2 cm long, often in groups along a wall.
- 2A dark, greasy band at the foot of walls and on corners, where the fur rubs on every pass.
- 3Burrow openings at the base of walls, under paving or in flower beds, with freshly dug soil.
- 4Gnawed bags, doors or ducts; scurrying at night inside wall linings or false ceilings.
Nuisance level
An indicative guide from our technicians, from 1 (moderate) to 5 (high).
- Health
- 5/5
- Damage
- 5/5
- Breeding
- 4/5
Why act
- Leptospirosis: the bacterium is shed in urine and survives in water and damp soil. Cases have been notifiable in France since 2023.
- Food and surfaces soiled by urine and droppings.
- Gnawed cables and ducts: breakdowns, short circuits, fire risk.
- Fast breeding: a female can have several litters a year from just a few months old.
Our treatment, in four stages
- 01
Locate
Locate: survey of droppings, smears and burrows, inspection of drains and ducts, plan of entry points and runs.
- 02
Treat
Treat: rodent control with tamper-resistant bait stations, secured and numbered, loaded with an approved rodenticide; mechanical traps where bait has no place.
- 03
Check
Check: follow-up visit built into the protocol, bait uptake read station by station, stations moved or added if activity continues, bait removed at the end.
- 04
Prevent
Prevent: holes sealed (steel wool and mortar), grilles on vents, door sweeps, photo report and advice for staying actively vigilant.
Good everyday habits
What you can do to lower the risk of a new infestation.
- Use lidded bins and never leave a bag on the ground.
- Avoid feeding pigeons or stray cats in the courtyard.
- Fit vents and air bricks with fine mesh (under 1 cm).
- Clear out cellars and plant rooms: less clutter means fewer hiding places.
Your questions
How can I tell a rat from a mouse?
Droppings usually settle it: 1–2 cm for a rat, a few millimetres for a mouse. The brown rat has a heavy head and short ears; the mouse is slight, with large ears and a tail as long as its body.
Is my dog or cat at risk?
Bait is placed in closed, secured stations designed so that children and pets cannot reach it. If you still suspect your pet has eaten rodenticide, call a vet straight away: an antidote exists.
Why do rats sometimes come back after treatment?
Usually because a gap was left open and other rats from the network moved in. That is why the Repère Protocol ends by sealing the entry points identified at the start.
Brown rats in your home or your business?
Flat, house, restaurant, shop or office: price including VAT shown before you book, 2-hour window, same-day photo report and advice to lower the risk of a return.