Why sound identification matters before you do anything else
The most expensive mistake you can make in wildlife control is treating the wrong animal. A one-way door sized for a squirrel won't stop a raccoon. A bat exclusion done outside the August 15 to October 31 window BC regulations require is both illegal and ineffective. Rodent bait left in an attic occupied by a denning family of raccoons is a welfare problem and a liability. You need to know what you have.
Sound is your first and best clue. After fifteen years of attic inspections across Metro Vancouver, from the split-levels of Burnaby to the heritage wood frames of Strathcona, I've learned that most homeowners can identify the species from sound alone if they know what they're listening for. This guide is what I tell every caller before we book.
Start with time of day
Time of day filters out most species immediately. Norway rats (Rattus norvegicus) and roof rats (Rattus rattus) are primarily nocturnal, most active between 9 pm and 3 am. Squirrels are strictly diurnal — if the sound stops before 7 pm and doesn't resume until after sunrise, you almost certainly have a squirrel, not a rat. Raccoons are crepuscular, heaviest between 11 pm and 5 am. Bats are creatures of the very first darkness, most active in the 20-minute window after civil twilight. Birds are daytime only. If you're hearing sounds in the middle of the night that pattern like running water or distant rolling, that's the scenario most people misread as plumbing.
| Species | Active hours | Sound character | Movement pattern | Volume |
|---|---|---|---|---|
| Norway rat (Rattus norvegicus) | 9 pm – 3 am | Rapid scratching, gnawing on wood | Fixed routes along joists | Low to moderate |
| Roof rat (Rattus rattus) | 9 pm – 2 am | Light scurrying, softer scratch | Along top plates and rafters | Low |
| House mouse (Mus musculus) | 10 pm – 4 am | Very faint scratching, almost inaudible | Erratic, short bursts | Very low |
| Eastern grey squirrel (Sciurus carolinensis) | 6 am – 6 pm | Rolling, bounding, loud thumps | Energetic, unpredictable | Moderate to loud |
| Raccoon (Procyon lotor) | 11 pm – 5 am | Heavy dragging, vocalisation if kits present | Slow, deliberate, shuffling | Loud |
| Little brown bat (Myotis lucifugus) | Dusk, 20-min window | Dry chittering, papery scratch in wall cavities | Clustered at roost site | Very low |
| Starling / House sparrow | 6 am – 7 pm | Shuffling, chirping, bill-tapping | Fixed nest site, infrequent movement | Low to moderate |
| Paper wasp colony in soffit | Daytime only | Constant low buzz or hum, no impact sounds | No physical movement sounds | Very low hum |
Rats: the fixed-route scratchers
Norway rats and roof rats are the most common attic occupants in Metro Vancouver, and both have a behavioural tell that's hard to miss once you know it: they run fixed routes. A rat that's been in your attic for more than two weeks will have worn a path through the insulation. You'll hear the same scratching sound in the same location at roughly the same time each night. It's rhythmic and repetitive in a way that feels almost mechanical.
Norway rats, being larger and heavier at 200 to 500 grams, produce a deeper, dragging scratch — sometimes you'll hear them chewing on wood or pipe insulation, a gnawing sound that's slower and more deliberate than the running. Roof rats are lighter (150 to 250 grams) and tend to travel higher in the structure, along top plates, rafters, and inside soffit cavities. Their sound is airier, a soft patter more than a scrape. If the sound seems to come from high in the wall or from the soffit line, suspect roof rats first.
Squirrels: the morning thumpers
Eastern grey squirrels (Sciurus carolinensis) are the second most common attic wildlife call in Vancouver, particularly in the mature tree canopy neighbourhoods of Kitsilano, Point Grey, Dunbar, and South Granville. The identifying characteristic is timing and energy. Squirrels don't creep. They bound, roll, and thump with a physical enthusiasm that sounds almost comical from below. You'll hear what sounds like a small animal doing gymnastics at 6:30 in the morning, which is exactly what's happening.
A squirrel in your attic is almost always nesting, and if you're hearing the sound in winter or early spring, there's a reasonable chance there's a litter involved. Squirrels in BC typically have two litters per year, roughly February to March and again in July to August. A nesting female will be quieter than usual for the first two to three weeks after giving birth, then dramatically louder as the kits become mobile. If the sound disappears for two weeks and then comes back with multiplied energy, the litter has arrived.
Raccoons: the shufflers in the dark
Raccoons (Procyon lotor) are the one attic species that genuinely scares people when they first hear it, and with some reason. A large adult raccoon weighs between 5 and 10 kilograms. When one moves across your attic in the middle of the night, the sound is not subtle. Think heavy footsteps, slow and deliberate, combined with shuffling or rearranging, as though someone is moving furniture above your head. If there are kits present, from late April onward in Metro Vancouver, you may hear a distinctive churring or mewling sound that new homeowners sometimes mistake for a malfunctioning HVAC unit.
Raccoons in attics are legally the most complex animal to deal with in BC. The Wildlife Act (RSBC 1996, c. 488) protects raccoons from lethal control in most circumstances, and females with kits cannot be removed without relocating the family unit together. DIY eviction of a denning raccoon risks creating a welfare situation where kits are separated from their mother and die in the structure. Call a licensed wildlife company for any raccoon in an attic, and call them immediately if you suspect a spring litter.
Bats: the dusk scratchers in the wall
Little brown bats (Myotis lucifugus) and big brown bats (Eptesicus fuscus) are both resident in Metro Vancouver, and both roost in the narrow cavities between wall plates, behind soffit boards, and inside attic spaces. The sound signature is unlike any other attic species: a dry, papery scratching or chittering that begins almost exactly at civil twilight and lasts for 15 to 30 minutes as the colony emerges to feed. If you sit outside your house in August at 9 pm and watch the roofline, you may see them exit one by one from a gap in the soffit or fascia.
The critical regulatory fact: bat exclusion in BC is governed by the Wildlife Act and by Bat Conservation Canada guidelines, and it is seasonal. Exclusion work must not occur between May 1 and August 15, when maternity colonies with flightless young are present, or between November 1 and March 31, when hibernating bats cannot be evicted without dying. The legal exclusion window is August 16 to October 31. Any company that offers bat removal outside this window should be disqualified immediately.
Birds and wasps: the edge cases
European starlings (Sturnus vulgaris) and house sparrows (Passer domesticus) nest in soffit gaps and attic vents, particularly in the 1950s to 1970s bungalow stock common in Burnaby, Coquitlam, and South Surrey. The sound is a constant shuffling and chirping during daylight hours, heavier in spring. Paper wasps (Polistes dominula) and yellow jackets (Vespula spp.) in a soffit or wall cavity don't produce impact sounds at all. What homeowners hear is a faint, constant hum that intensifies during warm afternoons. If you're not hearing anything that sounds like a physical animal moving, press your ear to the drywall in the area of concern. A wasp colony in a wall void will transmit through to the interior surface.
What to do with the information
Once you've narrowed the species, the response changes significantly. For rodents, get a professional exclusion inspection booked within a week — every day of active rodent occupation increases insulation damage, wiring risk, and the chance of a secondary infestation through the same entry points. For squirrels, the same urgency applies but the season matters: if it's between February and September, assume nesting until proven otherwise. For raccoons, call immediately and do nothing to the entry point in the meantime. For bats, note the date and check against the BC exclusion window before booking any work.