Squirrels in the Attic: Ontario's Fall Nesting Season and Why Trapping Isn't the Answer

Quick answer: Squirrels move into Ontario attics from late August through October, when the year’s second litter is weaning and adults start scouting a warm place to overwinter. Trapping and relocating almost never solves it, because Ontario law requires captured wildlife to be released within 1 kilometre of where it was caught — the same squirrel simply walks back to the same hole. The fix that lasts is exclusion: get the animals out, then permanently seal the roofline entry point they were using. Call (705) 302-1887 or take the free quote quiz.

Why fall is when squirrels come indoors in Ontario

Grey squirrels in southern Ontario raise two litters a year — one in late winter, one in mid-summer. By late August that second litter is weaned and the young are looking for territory of their own, at exactly the moment the adults start thinking about where they will spend a Simcoe County or Muskoka winter.

Squirrels do not truly hibernate. They stay active all winter, living off cached food and relying on a sheltered, insulated den to get through the cold snaps. A tree cavity works. A soffit corner over a heated house works considerably better — it is dry, it is warm from below, and it already comes lined with fibreglass batting that shreds into perfect nesting material.

That is the whole story of the fall attic problem. Nothing has gone wrong with your house. Your house is simply the best den site on the block, and September is when the shopping happens.

Two things make this a Sani IQ region problem in particular. Mature tree canopy — the kind you get in older Richmond Hill neighbourhoods, established Innisfil subdivisions and almost every lakeside lot in Muskoka — puts branches within jumping distance of a roofline. And seasonal properties give squirrels something they rarely get: months of undisturbed quiet to chew, nest and breed inside a structure nobody is checking.

Is it squirrels, or is it mice?

This is the single most useful diagnostic a homeowner can run, because it decides who you call and what actually gets done.

Time of day is the giveaway. Squirrels are diurnal. You will hear them at first light and again in the hour before dusk, and they go quiet overnight. Mice are nocturnal — they get loud after you turn the lights off and settle down by morning. If the noise wakes you at 2 a.m., you are almost certainly dealing with rodents rather than wildlife, and mice are a different job with a different fix.

Weight and direction tell you the rest. Squirrels sound like something rolling or dragging — nuts moved across a ceiling, a body-sized thump, running that has clear direction and stops abruptly. Mice sound like fingernails: fast, light, scratchy, staying inside a wall cavity rather than crossing open space above your ceiling.

Look outside, not just up. Squirrel entry points are visible from the ground with a pair of binoculars. Check the roofline junction where two rooflines meet, the soffit returns at the corners, gable and roof vents, the fascia board edge, and any spot where a chewed hole has left a bright, pale ring of fresh wood around a dark opening. Mice do not leave marks you can see from the driveway.

If you want a plain-language reference on the animals themselves, our wildlife removal page covers the species we deal with across Ontario, and the Sani IQ pest library is the identification reference for everything else that shows up this time of year.

Why trapping and relocating almost always fails

This is where most homeowners lose a season and a few hundred dollars.

Ontario’s rules for a property owner dealing with a wild animal damaging their property are specific. If you capture the animal alive, you must release it within 1 kilometre of where it was captured, within 24 hours. There is no legal option to drive a squirrel out to the country and let it go.

A squirrel’s home range is comfortably larger than 1 kilometre. Released at the edge of that circle, an adult grey squirrel is back at your soffit the same day — and the hole is still open, because trapping does nothing to the hole. This is why people describe catching “six squirrels” over a fall. Often they caught the same two several times.

Then there is the part that turns a nuisance into a real bill. If you trap a nursing female in September and remove her, you have not removed the litter. Young squirrels left in a wall void die there, and the resulting odour problem requires opening the ceiling to resolve. Timing and technique are not optional details here; they are the whole job.

The professional approach inverts the order. You confirm the active entry point, you install a one-way door that lets the animals leave and prevents re-entry, you verify the space is empty, and only then do you seal — permanently, in materials a rodent cannot chew through, which means heavy-gauge steel mesh and hardware, not spray foam and not a piece of screen stapled over the gap.

The damage nobody sees until later

Squirrels are rodents, and rodent incisors grow continuously. Chewing is not aggression; it is dental maintenance. In an attic, the available surfaces to chew are roof sheathing, plumbing vent stacks, and wiring.

Chewed wiring in an attic is a genuine fire risk, and it is the reason a squirrel problem should not sit through a winter “until spring.” Beyond that, a season of occupancy typically means compressed and soiled insulation across the nesting area — which quietly raises heating costs — plus urine and droppings contamination and, in the older housing stock across Ajax and much of Durham, water damage where a chewed vent boot has been letting weather in.

The economics are worth being blunt about. A single squirrel season in an attic frequently costs more in insulation replacement, electrical inspection and drywall repair than a full year of protection on your home costs to prevent it.

What to do this month

Walk your roofline with binoculars. From the ground, on all four sides, in good light. You are looking for holes at soffit corners, damaged roof vents, gaps where the fascia meets the roof edge, and staining or rub marks on a favoured route.

Trim the runway. Squirrels can jump roughly two metres horizontally. Branches within that distance of your roof are a bridge; cutting them back removes the easiest route in. This is genuinely the highest-value hour of work a homeowner can do in September.

Cap the obvious openings. Uncapped chimneys and unscreened roof and gable vents are open invitations. Screen them with metal, not plastic.

Listen at 6 a.m. and 7 p.m. for a week and note where the sound is. Location and timing shorten a technician’s diagnostic considerably.

Do not seal a hole you have not verified is empty. Sealing an active entry point traps animals inside — the most expensive mistake in this entire article.

Getting it handled properly

Every Sani IQ job starts with a $95 professional inspection, credited in full when you book the treatment. For a suspected attic problem that inspection is the whole value: it confirms what species you have, whether the space is currently occupied, where the animals are getting in, and what the exclusion work actually requires — instead of guessing from the ground.

Here is the part worth thinking about carefully. Getting this year’s squirrels out is a one-time job. Keeping your home from being chosen again is not, because the conditions that made your roofline attractive — mature trees, aging soffit, a warm attic — are still true next September, and next September, and the one after.

That is what our annual plans are built for. Essentials at $1,195 puts your property on a scheduled year-round program with the perimeter maintained through every season, so the small openings that become big problems get found on a visit rather than by an animal. VIP from $1,395 extends that coverage further for properties with more exposure — bigger lots, older structures, cottage and lakeside properties that sit empty for stretches. If your main concern is the rodent side of the same roofline, Complete Mice Protection at $895/year is the targeted version.

The one-time visit solves this fall. The plan is what stops you from reading this article again next fall.

Sani IQ is owner-operated, licensed under the Ontario Pesticides Act and registered with the MECP, BBB Accredited, and carries $5 million in liability coverage. Our technicians are employed by us, licensed and background-checked — never subcontracted. We hold a 5.0 rating across 126 Google reviews, and one-time services carry a 60-day guarantee.

Call (705) 302-1887, or take the free quote quiz and we will come back to you with a plan for your specific property.

Frequently asked questions

How do I know if squirrels are in my attic or just on my roof? Roof traffic is intermittent and follows no pattern. Attic occupancy produces noise at consistent times — dawn and dusk — from the same area, day after day. Sustained early-morning activity in one spot means they are inside.

Can I get squirrels out of my attic myself? You can do the preventive half yourself: trim branches, cap vents, screen openings before anything moves in. Removing an active family is a different job, because Ontario’s 1 km release rule makes DIY trapping largely ineffective and mistimed removal in September risks leaving dependent young sealed in a wall void.

Is it legal to relocate a squirrel in Ontario? Live-captured wildlife must be released within 1 kilometre of the capture site and within 24 hours. Driving an animal out of the city and releasing it is not permitted, and at that distance it would return anyway.

What time of year do squirrels move into attics in Ontario? Late August through October is the main window, driven by the second litter dispersing and adults selecting an overwintering den. A second, smaller push follows in late winter with the first litter.

Will squirrels leave the attic on their own in spring? Some do. But they leave the entry hole behind, and an established den site tends to be reoccupied — often by the next generation. The hole is the problem, not the current tenant.

How much does it cost to get squirrels out of an attic? It depends entirely on the entry points, roof access and the extent of any damage, so it is quoted after inspection rather than off a list. The $95 inspection is credited in full when you book the work.

What is the noise difference between squirrels and mice? Squirrels: dawn and dusk, heavier, rolling or dragging sounds, movement across open ceiling space. Mice: after dark, light and scratchy, staying within wall cavities.