Rodents near you

Rodents are mostly active at night, so the evidence usually shows up before the animals do. These are the signs Health Canada and exterminators look for.

Traps and bait only deal with the rodents already inside; exclusion stops the next ones. Health Canada notes that a mouse can squeeze through a crack the size of a dime and a rat through a hole the size of a quarter, so a proper inspection covers the whole building envelope, from the foundation to the roofline. Foam and caulk on their own don't hold, because rodents chew through them; the Public Health Agency of Canada recommends wire screening, steel wool, metal flashing or cement instead.

Once entry points are sealed, the rodents still inside have to be removed. Health Canada describes several kinds of trap: snap and electronic traps generally kill instantly, live traps close a door when the animal walks in, and glue traps can be used with or without bait. Each option has trade-offs for a household.

Rodenticides are poisons designed to kill mammals, which is exactly why they are risky for children, dogs, cats and wildlife that eat poisoned rodents. Health Canada says poisoned baits must be used in a tamper-proof bait station wherever children and pets can reach them, and warns that anticoagulant products are usually highly toxic.

The rules for products sold to consumers are stricter than many people realize. Health Canada prohibits domestic class products containing the second-generation anticoagulants brodifacoum, bromadiolone and difethialone, requires domestic products to be sold packaged with a bait station, and allows only block or solid baits: loose pellets, meal, liquids and concentrates meant to be diluted are prohibited. More potent commercial products are applied by licensed exterminators.

If a child or pet may have eaten bait, call a poison centre or a veterinarian right away and keep the package on hand.

Health Canada names the deer mouse as the most common carrier of hantavirus, which spreads mainly when people breathe in particles from the droppings, urine or saliva of infected rodents. That is why the most important rule is never to sweep or vacuum dry droppings. The Public Health Agency of Canada sets out the steps below for a small cleanup; heavy contamination in an attic, crawl space or cottage is a job for a professional.

The City of Toronto says property owners and businesses are responsible for managing rats on their property, while the City maintains public property and enforces bylaws on waste and property standards. It asks residents to store garbage in animal-resistant containers with tight-fitting lids, keep the green bin locked, keep the area around bird feeders and bird baths clean, and seal cracks and small holes around the house, garage and shed. Tenants should go to the landlord or property manager first, then call 311 if nothing is done.

The City of Montréal explains that rats often surface when sewers and drains are damaged or during excavation work, and that meal scraps flushed down the toilet or put in a garbage disposal can draw them in. A tenant who sees rats in a dwelling must notify the landlord right away, and the owner must call a certified exterminator and make the necessary repairs; rats in parks, alleys and other public spaces are reported to 311. In Ontario, the Landlord and Tenant Board also names mice among the pests a landlord must take steps to control.

As temperatures drop, mice look for warm, sheltered spots near food, and a house with a gap at the foundation is an easy choice. Health Canada notes that deer mice may invade buildings near fields and woodlands in the fall. Late summer and early fall are the best time to have entry points sealed, before the first cold nights, and to tidy the yard: firewood stacked away from the house, spilled bird seed cleaned up, plants trimmed back from the walls and garbage secured.

Cottages and seasonal homes deserve extra care. Closed up for months, they give mice undisturbed nesting space, so the first visit in spring should start with airing out and the safe cleanup steps above, never a quick sweep.