Brown rat: recognising the Norway rat and keeping it out
It lives beneath your feet, in cellars and sewers, and comes up wherever a gap is left open.
The short answer
The Norway rat (Rattus norvegicus) is the rat of French cities: a stocky rodent 20–28 cm long without the tail, mostly nocturnal, nesting at ground level and in drains. Its urine can transmit leptospirosis, a notifiable disease in France since August 2023. Getting rid of it for the long term means baiting with secured stations and closing the routes it uses.
Identity card
Scientific name: Rattus norvegicus
- Size
- 20–28 cm without the tail; tail slightly shorter than the body; 200–500 g as an adult
- Appearance
- Grey-brown above, pale grey below; blunt muzzle, short ears, stocky build
- Life expectancy
- One to two years in the wild; sexually mature at around 2–3 months
- Active period
- Mainly at night, all year round; seen by day when numbers are high
- Where it hides
- Sewers, cellars, crawl spaces, bin stores, courtyards, banks and gardens
How to spot brown rats
Tick off in your head what you have seen: the more the clues overlap, the surer the diagnosis.
- Spindle-shaped droppings 1–2 cm long, clustered along runs and near food.
- Dark, greasy smears low on walls, on pipes and around holes, where the fur rubs on every pass.
- Burrows at the foot of walls, under paving or in flower beds, with fresh soil spoil.
- Gnawed bags, skirting boards, ducts or door bottoms, and scurrying at night in ceilings or partition walls.
- A lingering smell of ammonia in a cellar or closed room.
Understanding how it behaves
A brown rat does not wander at random. Night after night it runs the same routes, hugging the walls, between its burrow, a water source and its food: bins, stores, pet bowls, seed dropped from a bird feeder. That routine is exactly what lets a technician read an infestation.
It is also wary of anything new (known as neophobia): a trap set right in its path can be ignored for days. Shop-bought baits scattered at random often fail for that reason, and because they leave the ways in wide open: unscreened cellar vents, loose manhole covers, cracked pipes.
Whether in a home or a business, the French departmental health regulations require owners and occupants to take the necessary steps against rodents. For a restaurant or food shop, pest control is also part of the hygiene rules set by EU Regulation (EC) No 852/2004.
Why it shouldn't be left
- Leptospirosis: the bacterium, shed in urine, survives in water and mud and enters through a cut or the mucous membranes.
- Food, packaging and surfaces soiled with urine, hair and droppings.
- Gnawed cables and conduits: breakdowns, short circuits, fire risk; damaged insulation and pipes.
- Numbers rise quickly: a gestation of about three weeks and several litters a year.
- For a food business: a failed hygiene inspection and a damaged reputation.
What the technician does: brown rats
01
Inspect
The technician follows the runways, looks for fresh droppings, burrows, manholes and pipe penetrations, then draws up a plan of entry points and high-risk areas.
02
Treat
Secured bait stations, closed and anchored, loaded with an approved rodenticide and placed on the rats' real routes; snap traps where bait is unsuitable, for example near food.
03
Sanitise
Holes packed with steel wool and mortar, mesh on cellar vents and air bricks, door sweeps, non-return valves on drains where needed; advice on storage and waste handling.
04
Follow up
Follow-up visit as set out in the protocol: bait uptake recorded, stations adjusted, bait removed at the end of treatment; photo report and active vigilance between visits.
Prevention, at home and at work
Simple habits that lower the risk of the intruder settling in or coming back.
- 01At home: use bins with lids and put bags out on collection day, not the night before.
- 02Don't leave pet food, leftovers or bird seed on the ground in the garden or courtyard.
- 03Fit fine mesh over cellar vents and air bricks, and fill the gaps around pipes.
- 04Clear out the cellar: boxes and clutter piled on the floor make perfect shelters.
- 05In a business or apartment building: keep the bin store clean and closed, log any signs you see and have the stations checked at regular intervals.
Your questions
How can I tell whether it's a rat or a mouse?
Compare the droppings: 1–2 cm for the brown rat, 3–6 mm for the mouse. The rat has a heavy body, small ears and a tail shorter than its body; the mouse is slight, with large ears and a tail as long as its body.
What can I do myself before the visit?
Cut off access to food (closed bins, food in containers), note where you find droppings or marks, and hold off on blocking holes that are still in use: the technician needs to see them to understand the routes. Never handle droppings or carcasses with bare hands.
When should I call a professional?
As soon as you see fresh droppings, a burrow or a rat in daylight: these point to an established population. The earlier the visit, the lighter the set-up needed.
Are my children or pets at risk from the bait?
Bait is held in stations that open only with a special key and are fixed to the floor or wall, designed so that a child or animal cannot reach it. If you think a pet has swallowed an anticoagulant, contact a vet straight away: vitamin K1 is the antidote.
Why do rats sometimes reappear after treatment?
A colony that has been removed leaves room that other rats from the network can take over if the entry points stay open. That is what the Sanitise step of the Sentinel Protocol is for: fill, screen, then check at the follow-up visit.
Brown rats at home or on your premises?
2-hour slot, 7 days a week from 8 am to 8 pm, price shown and paid online, photo report emailed on the day of the visit.
Related service: Rodent control: rats and mice
