"It starts around half past midnight, always in the same spot: above the headboard. It sounds like someone rolling a marble across the floorboards. My husband says it's the roof timbers shifting. Except the timbers don't stop when we bang on the ceiling." This resident of Saint-Maur-des-Fossés took six weeks to accept the obvious: what she was hearing was an animal, and it had a route.
Night noise is almost always the first sign of an infestation in a house — long before the droppings, long before the damage. It is also the most poorly used sign: people listen to it with anxiety, not with method. Yet the time it appears, the height of the sound, its rhythm and its duration are enough to steer a diagnosis with surprising reliability. That is exactly what a technician does during the first five minutes of a visit: he asks questions about the sound before climbing into the loft.
This blog has already covered locating the nest within the structure, reading droppings and the noises made by larger mammals in the loft. This article covers the step before that: how to listen, take notes and interpret a night noise so you know what is living in your home — and where to go and check first thing the next morning.
Why at night, and why in November
Commensal rodents (house mouse, brown rat, wood mouse, black rat) are mostly nocturnal, with two activity peaks: one at dusk, roughly 30 to 60 minutes after nightfall, and a second before dawn. This is anti-predator behaviour, not coincidence: daytime human activity and visual predators push them into darkness.
In November, two factors combine in the Val-de-Marne:
- Night falls around 5:15 p.m. The first activity peak therefore shifts right into the window when people are at home, which mechanically increases the number of reports. A noise heard at 6 p.m. in November is the same noise as at 10 p.m. in July.
- The heating is on. Partition walls, conduits and lofts warm up, the building becomes attractive, and the silence of the house at night is more complete than in summer with the windows open.
The result: November to February accounts for the bulk of "I can hear something" calls from houses, including from populations that had already been present since autumn without being detected.
The listening method: four pieces of information to record
Before calling anyone, keep a log over three consecutive nights. A simple sheet of paper by the bed is enough. Four columns:
- The exact time (start and end of each sequence).
- The location: which room, and above all the height — ceiling, mid-wall, skirting board, under the floor.
- The nature of the sound: scratching, rubbing, rolling, running, squeaking, gnawing, dull thud.
- The duration: a few seconds, or several minutes at a stretch.
For location, a field tip: record it. A phone placed on the floor in the hallway, set to voice-recorder mode, all night long, gives you a usable timeline that memory simply cannot reproduce. Owners who want to go further install a small night-vision security camera in the attic or facing a suspect skirting board: by far the fastest way to find out whether you are dealing with a mouse or an animal the size of a stone marten.
A noise that stops dead when you bang on the ceiling, then starts again three to five minutes later, is an animal noise. Shifting timber and an expanding pipe do not react to your footsteps.
Matching chart: which noise, which animal
This is the heart of the diagnosis. The sounds below are those most often found in the 1950s–1980s houses of the Champigny – Nogent – Créteil area.
| What you hear | Height / area | Most likely explanation |
|---|---|---|
| Small, quick, light scratching in short 2–5 s bursts | Skirting boards, bottom of walls, behind appliances | House mouse |
| A distinct rolling sound, like a marble or a nut rolling | Loft floorboards, suspended ceiling | Wood mouse or a mouse carrying a seed / hazelnut |
| Heavy running, you can "feel" the weight, irregular rhythm | Loft floorboards, under the ground-floor flooring | Brown rat (sewer rat) |
| Steady, slow, almost mechanical gnawing | Partition wall, roller-shutter box, roof timbers | A rodent gnawing wood or conduit |
| Very brief high-pitched squeaks, sometimes in series | Partition wall, behind a low unit | Squabbling or a mouse litter nearby |
| Rustling material, a papery sound | Loft insulation, storage boxes | Nest building |
| Movement only between 5 p.m. and 8 p.m., then silence | Roof, under the tiles | Bird or bat (protected) |
| Infrequent heavy noise, sometimes a mewing or hoarse cry | Loft, roof timbers | Stone marten or other mammal: do not intervene yourself |
Two classic traps are worth flagging.
The roller-shutter box. In many houses this is a hollow box connected to the outside, poorly insulated and accessible from the facade. Mice get in, nest there, and the noise is carried through the whole room by the sounding box. Owners search the walls for weeks while the nest sits 20 cm from the window.
The electrical conduit. A mouse moving along a conduit set into the wall produces a strangely "linear" noise that seems to travel right through the wall. That is usually exactly what is happening, and it is the scenario that should make you move fast: damage to cable insulation is the leading cause of rodent-related electrical incidents. We covered this aspect in the article on rodent damage and home insurance.
Telling an animal noise from a building noise
Every house makes noise at night, and panic leads to over-interpretation. Three simple tests rule out false positives.
1. The thermal correlation test
Expansion noises (roof timbers, floors, heating pipes, ducts) follow temperature cycles: they appear when the heating starts up or shuts down, and when the night cools down around 4–5 a.m. They are sharp, isolated, not repetitive: a single "clack", not a sequence. If your noises coincide with the boiler timer, look at the building first.
2. The paper test
Lay a strip of thin white paper — or sprinkle a fine layer of flour over 40 cm — on the floor where you suspect a route: along a skirting board, at the garage threshold, in front of the loft hatch. The next morning, footprints, tail drag marks or soiling confirm the passage in a single night. It is free, non-toxic, and far more informative than an hour of listening.
3. The smell test after ten days
An established population leaves a characteristic ammonia smell, recognisable in a confined space: loft hatch, under-stairs cupboard, crawl space. If the noise has lasted two weeks and the smell is there, the diagnosis is made.
