Match the sound to the species
| Sound | Time | Location | Likely species |
|---|---|---|---|
| Light scratching, soft scurrying | 9pm-3am | Inside wall cavity, behind baseboards | House mouse |
| Heavier scratching, thumping, dragging | 10pm-4am | Floor level, basement, crawlspace | Norway rat |
| Scratching at ceiling, running overhead | 10pm-4am | Attic, ceiling, upper walls | Roof rat |
| Loud scratching, midday and dusk | Daylight + dusk | Attic, soffit | Grey squirrel |
| Squeaking, faint chirping | Variable | Wall cavity, attic | Bat (May-Sep) or juvenile rodents |
| Slow scraping, occasional | Any time | Inside wall | Carpenter ants or insect activity |
Why the time of night matters
Rodents are crepuscular and nocturnal — most active during the first three hours after sunset and the last two hours before dawn. If you hear activity at midnight, that's textbook rodent behaviour. Daytime activity, by contrast, points away from rats and toward squirrels (which are diurnal) or, in extreme stress conditions, a heavily population-pressured rodent infestation pushing into daylight foraging.
Why the height matters more than the time
If the sound is at ceiling level — directly above your bed, in the upper wall, or in the attic — suspect roof rats first. This is especially true in older Vancouver west-side homes (Kitsilano, Dunbar, Kerrisdale), Burnaby Heights, North Van, and any home with mature tree canopy contacting the roof. Roof rats access the attic via tree branches, then run along ceiling joists. Ground-level sounds — basement, crawlspace, behind a kitchen toe-kick — point to Norway rats or house mice.
What you can do tonight to confirm
- Sit quietly in the room where you hear the sound, lights off, between 10pm and midnight. Note the exact wall or ceiling location each time you hear it. Activity at the same spot two nights in a row indicates a runway, not a passing visitor.
- Tape a piece of paper across a suspected entry point inside the home (under a sink, behind a stove). If it's torn, chewed, or moved within 24 hours, you have rodents.
- Check the attic with a flashlight at dusk — droppings on insulation, runway smudges along beams, gnaw marks on wood are all confirming.
- Sniff for ammonia in the suspected area. Concentrated rodent urine has a distinctive smell that becomes obvious when you know what you're checking for.
- Check for greasy 'rub marks' on baseboards, behind appliances, and along studs visible in unfinished basement spaces — rats follow consistent runways and leave fur-grease residue.
Frequently asked questions
Can it be the house settling?+
Could it be plumbing?+
I only hear it in winter — does that mean they go away in summer?+
Should I knock on the wall to scare them out?+
Next steps once you've identified the species
Knowing the species from sound is a starting diagnostic — it tells you which specialist inspection to request and where to look first. Roof rats overhead in a North Vancouver home with mature Douglas fir canopy: inspect the soffit-fascia junction and trim any branches within 1 m of the roof. Norway rats at floor level in a Richmond property adjacent to the dyke system: focus the inspection on crawlspace vents, foundation perimeter, and the deck-house junction. House mice in an East Vancouver basement: utility penetrations, dryer vent, door bottoms, and crawlspace vents. Read our detailed entry-point map at [The 24 Most Common Rodent Entry Points](/guide/rodent-entry-points).
When the sound doesn't fit any species
Occasionally homeowners describe sounds that genuinely don't fit the rodent pattern — slow rhythmic tapping, a single scraping event that doesn't repeat, clicking sounds. These can be carpenter ants (especially in the late spring wet season in Metro Van), plumbing thermal expansion, or wildlife entering a crawlspace that isn't a rodent. Bats are worth noting: they produce a soft chirping and wing-flutter sound in wall voids from May through September — entirely different from the mechanical scratch-and-run of a rat or the light scatter of a mouse. If you hear high-pitched intermittent chirping in summer months, suspect bats before rodents. Bat exclusion in BC follows different regulations and a different season window.
Attic sounds vs wall cavity sounds: the structural difference
Attic sounds are overhead and travel laterally — the running sound follows a path, often predictably, because roof rats follow joist lines. Wall cavity sounds are more local and vertical — mice and Norway rats often move up and down pipe chases and wall cavities between floors. If you hear a consistent running path that goes from one side of the ceiling to another, it's almost certainly a roof rat on a ceiling joist runway. A scratching that starts and stops without moving suggests a mouse or juvenile rat in a cavity nest. Knowing which helps your tech prioritize during inspection — attic-first vs wall-cavity-first changes what equipment they bring.
Why Metro Vancouver homes are noisier than Calgary homes
Calgary's −20°C winters cull juvenile rodents and reduce overwintering populations. Metro Vancouver rarely freezes. A rodent colony established in October doesn't face the January population pressure that forces activity outdoors or kills juveniles. The colony continues breeding indoors, growing through winter, which is why Metro Vancouver homeowners hear more activity — particularly in January and February — than they would in colder Canadian cities. The City of Vancouver's mild-winter baseline also means that exterior food sources (bird feeders, compost, fruit trees) remain available longer, reducing pressure to enter structures until late November rather than September. When pressure does build, it builds fast.