Bat work is the one job on this site where doing it at the wrong time is genuinely worse than not doing it at all. Worse for the building, worse for the animals, and unlawful besides.
So if you have found bats in July and somebody has offered to sort it out this week, this page is the reason to say no, and the reason waiting until late August is not us being unhelpful.
The legal position
Several of Ontario’s bat species have suffered catastrophic population declines from white-nose syndrome. The little brown myotis, once the commonest bat in this province, is among them. These species are protected under Ontario’s Endangered Species Act.
That has one practical consequence that governs everything else: there is no legitimate extermination approach to a bat colony.
Anyone offering to poison, fumigate or spray bats is offering something that is unlawful and does not work. A dead colony inside a roof is a decomposition problem, a mite problem (the parasites leave the carcasses and move into the building) and an odour problem, on top of the bats you started with.
The correct method is exclusion, and it is the only method we use for bat removal in Collingwood. You let the bats leave and prevent their return. That is the whole method, and the only variable is when.
The maternity window
Bats in this region form maternity colonies in early summer. Between roughly early June and late August, that colony contains pups that cannot yet fly.
Exclude the adults during that period and the mothers are locked outside. The pups starve inside your roof.
That outcome is inhumane, it is contrary to the species protections, and it leaves you with carcasses in the insulation and the odour and insect problems that follow. It is also entirely avoidable by waiting a few weeks.
So the windows are:
| Period | Exclusion? |
|---|---|
| Spring, before the pups arrive | Yes |
| Roughly early June to late August | No. Containment only. |
| Late August, once young are flying, through autumn | Yes, the best window |
| Winter | Generally not. Colonies may be torpid; work is unreliable and the roof is unsafe. |
Late August through September is the ideal window. The young are flying, the colony is still active and predictable, and the weather is workable.
What to do if you have bats now and it is July
This is the common call, and the answer is not “nothing.”
Contain rather than exclude. The goal is to separate the roost from your living space, not to seal the building. That means closing the routes a bat could use to get from the attic or wall cavity into a bedroom or hallway: gaps around light fixtures, attic hatches, service penetrations, and the tops of interior wall cavities.
That solves the part you actually cannot live with, and it leaves the colony’s exterior exits open so the adults can continue feeding the pups.
Then book the exclusion for late August. Our note on booking a bat exclusion in Collingwood for August covers why those weeks are the best of the year. We will tell you this rather than take the work now, and it is worth knowing that a company willing to do a full exclusion in July is telling you something about how it operates.
What a proper exclusion involves
| Stage | What happens | Why |
|---|---|---|
| Dusk emergence survey | Watch the building at dusk and record where bats actually leave | They use gaps you will not find from a ladder in daylight |
| Secondary sealing | Close every gap a bat could fit through except the confirmed exits | Otherwise they simply move a short way along the roofline |
| One-way devices | Fit to the confirmed exits | Bats leave, cannot re-enter |
| Settling period | Devices left several days to a week | Ensures the building is empty |
| Final seal | Remove devices, close the exits permanently | The permanent fix |
| Remediation | Guano removal, insulation assessment | Health and building fabric |
The emergence survey is the step that separates a job that works from one that does not, and it is the step most often skipped. Sealing the gaps somebody guessed at, while leaving the real exit open, produces a building that still has bats in it and an invoice that says otherwise.
Why this region gets it more than most
The Niagara Escarpment runs through the middle of The Blue Mountains and South Georgian Bay. Its crevices, caves and rock faces are natural bat habitat, and the townships behind it hold a great deal of century barn and outbuilding. Our page on pest control in The Blue Mountains covers the township itself.
Add chalets with complex multi-level rooflines through the Blue Mountains, older village housing in Thornbury and Clarksburg, and properties that stand empty for most of the week, and you have an unusually high concentration of buildings offering exactly what a maternity colony wants, with nobody in them to notice.
Guano
An established roost leaves accumulated droppings, and this is not simply mess.
Disturbing dry accumulated guano raises dust that can carry Histoplasma spores. It degrades insulation, and in quantity it loads a ceiling. Remediation is quoted separately from the exclusion, and on a colony that has been in place for years it can be the larger of the two numbers.
If a bat is in your living space
Stop and read this part specifically.
Do not release it. Contain it if you can do so safely (a container over it against a wall, then card slid underneath) and contact your local public health unit.
A bat found in a room with a sleeping person, a young child, or a pet is treated as a potential rabies exposure even when there is no visible bite, because bat teeth are fine enough that a bite may not be noticed. Post-exposure decisions depend on being able to test the animal, and once it is released outside that option is gone.
This is the one part of this page where the advice is time-critical and not ours to give beyond telling you who to call.