Rats and mice in Adelaide homes: three species, three different inspection approaches

Three rodent species share most of Greater Adelaide. The black rat (sometimes called the roof rat or ship rat) is the dominant species in suburban homes. It is an agile climber, a strong tree-line traveller, and almost always nests in roof voids, wall cavities, or above suspended ceilings. The Norway rat (sometimes called the brown rat or sewer rat) is heavier, less agile, and a committed burrower. It rarely climbs high and tends to live in subfloors, sewers, drains, and ground-level outbuildings. The house mouse is everywhere: pantries, wall cavities, drawers, under appliances, and inside stored goods.

Adelaide's rodent pressure follows three patterns. First, heritage suburbs with older construction (North Adelaide, Walkerville, Norwood, Burnside, Stirling) consistently flag higher activity due to more entry gaps in the building envelope. Second, autumn sees a clear migration indoors as outdoor weather cools, with peak inspection requests typically between March and June. Third, properties with attractants (poultry coops, compost bins, unsecured pet food, fruit trees, vegetable gardens) carry elevated pressure regardless of suburb.

A rodent inspection identifies the species first, because the species determines the search area. If the activity is in the roof void it is almost certainly black rats or house mice. If it is in the subfloor it is more likely Norway rats. Each species has different entry-point preferences, which the inspector documents for the sealing-and-exclusion work that follows trapping or baiting.

Black rats (roof rats): roof voids are the headline harbourage. Inspectors check above ceiling cavities, on top of insulation, around chimney penetrations, behind eave linings, inside wall cavities, and along plumbing chases. Black rats use overhead routes (tree branches, fences, power lines) to access the building, then enter through eaves, broken tile valleys, or fascia gaps.

Norway rats (sewer rats): subfloors, sewers, drains, and ground floors. Inspectors check subfloor crawl spaces, around foundation walls, under decking and timber outbuildings, in compost bins, near sewer access pits, and inside garden beds adjacent to the home. Norway rats burrow, so any soft soil mound or disturbed dirt against a foundation is a flag.

House mice: almost everywhere. Pantries, under and behind kitchen appliances, inside cabinetry voids, behind dishwashers, in laundries, inside garages with stored boxes, in roof voids, in wall cavities, and inside any rarely-disturbed storage. Mice need only a 6 mm gap to enter a building (the width of a standard pencil).

External attractants: the inspector also assesses what is drawing rodents to the property. Poultry coops, compost bins, fruit trees, open dog kennels, unsecured pet food, vegetable garden beds, and rubbish bin storage all increase pressure. Reducing attractants is a key part of the inspection report.

Night noise in the ceiling: scratching, scampering or running at night is the textbook first sign. Inspect within a week. The population grows fast and the wiring damage compounds.

Droppings in the pantry or laundry: visible droppings indicate indoor activity. The inspection identifies whether they are mice (almost certainly already inside the home) or rats (a more serious building-envelope issue).

Pet food disappearing: chewed packaging, missing dry food, and droppings near the bowl are classic signs of mouse or rat activity drawn to the attractant.

Pre-purchase: document existing rodent damage before contracts exchange. Insulation, wiring, plumbing and timber damage are all visible-on-inspection findings that can be negotiated on price.

Autumn migration: mid-March through June is the Adelaide peak for indoor rodent migration as outdoor weather cools. A proactive autumn inspection catches early activity before the colony establishes.

After garden or building works: any disturbance to soil, drains, foundations or roof can create new entry points. Inspect after the works to seal new gaps.