Signs You Have Mice in Your Ottawa Home This Winter

Ottawa winters push rodents indoors earlier than most homeowners expect. As temperatures drop below freezing in Barrhaven, Kanata, Orléans, and every other Ottawa neighbourhood, mice look for the warmest, driest place available — and that is usually your basement, attic, or wall cavities. By the time you hear scratching at night, mice have often been active in your home for weeks already. Catching the early signs saves you money and stops a small problem from becoming a full infestation before spring.

Ottawa's older housing stock is particularly vulnerable. Century homes in Centretown and Westboro, older bungalows in Alta Vista and Nepean, and even newer builds in Barrhaven and Stittsville all share the same weakness — gaps around foundations, utility lines, and window wells that mice exploit as the weather turns. A gap the width of a pencil is all a mouse needs to get inside.

1. Droppings Near Food Storage

Small, dark, rice-sized droppings near pantries, under sinks, or along baseboards are usually the first sign Ottawa homeowners notice. Fresh droppings are moist and dark; older ones dry out and turn grey within a few days. If you are finding droppings in more than one room, the infestation is likely more established than it first appears — mice tend to travel along consistent routes between their nest and food sources.

2. Scratching Sounds at Night

Mice are most active between dusk and dawn. Scratching or scurrying sounds inside walls, ceilings, or under floors — especially in older Centretown, Westboro, or Rockcliffe Park homes with wood-frame construction — is a strong indicator of nesting activity nearby. Ottawa homeowners often mistake this for squirrels in the attic, but the sound pattern is different: mice movements are quicker and more continuous, while squirrels tend to move in short bursts during daylight hours.

3. Gnaw Marks on Wires and Wood

Mice need to gnaw constantly to keep their front teeth from overgrowing. Chewed wire insulation, gnawed corners on cardboard boxes, or fresh wood shavings near baseboards are signs of an active presence in your Ottawa home — and a genuine fire hazard if electrical wiring is involved. This is one of the more expensive consequences of a mouse infestation left untreated over an Ottawa winter, since damaged wiring is not always visible until it causes a problem.

4. A Strong, Persistent Ammonia Smell

Mouse urine has a distinct, strong ammonia odour that becomes more noticeable in enclosed spaces like closets, cabinets, or crawl spaces. If you notice this smell in a specific area of your Ottawa home and it does not go away with normal cleaning, there is likely an active nest nearby. This is especially common in homes with unfinished basements, a very typical feature across older Ottawa neighbourhoods.

Why Ottawa Winters Make This Worse

Unlike milder climates, Ottawa's extended freezing season means mice have nowhere else to go once the temperature drops. Outdoor food sources disappear, and the warmth of a heated home becomes the single most attractive shelter option for miles. This is why rodent calls in Ottawa peak sharply from October through March — and why waiting until spring to deal with a suspected mouse problem almost always means dealing with a much larger colony by the time you call.

What To Do Next

If you notice any of these signs in your Ottawa home, act quickly. A single female mouse can produce dozens of offspring in a single season, and populations grow exponentially once established indoors. Store-bought traps can catch individual mice, but they rarely solve the underlying access problem — new mice will continue finding the same entry points all winter long.

A proper rodent control service starts with a full inspection to identify every entry point around your home's foundation, utility lines, and roofline, followed by trapping the existing population and permanently sealing the gaps mice used to get in. This combination — removal plus exclusion — is the only approach that actually stops the problem rather than just delaying it until the following winter.