Start with the droppings
Small, narrow pellets roughly the size of a grain of rice suggest mice. Adult brown-rat droppings are usually noticeably larger and thicker. Shape and size vary, so compare several clues rather than naming the animal from one dropping. Our droppings guide gives typical measurements and explains what to look for next.
Follow the damage
Check food packets, pet-food sacks, woodwork and the edges of stored boxes. Dark rub marks beside an opening can reveal a well-used route. Photograph what you find and note the location. A kitchen cupboard and a hole beside a shed may be parts of different problems, so avoid assuming every sign has the same cause.
If you see the animal
House mice have a pointed face and ears that look large for their head. Brown rats look heavier, with a blunter face and relatively smaller ears. A young rat can be mistaken for a mouse, so body size alone is not enough. A clear sighting or photo can help confirm the other evidence.
Let the location guide the next step
In a house, start around food cupboards and service pipes. In a garage or shed, inspect stored feed, wall edges and door gaps. Scratching in a loft needs a closer identification: squirrels, birds and bats can also use roof spaces. Sound alone is not a reason to put down rodent poison.
Expect different behaviour around new objects
Mice are often quick to investigate, while rats may avoid a new trap or bait station for several days. This wariness is called neophobia. Be patient with a well-placed rat setup and keep checking it. If signs appear in several places, plan several control points rather than expecting one trap to cover the whole problem.
Choose equipment for the animal you have confirmed
For rats, look at our Rat Box; for mice, compare the Compact and Double Mouse Boxes. Then choose compatible traps or suitable amateur bait using the location guides. Traps need accessible positions for daily checks. Alongside control, remove easy food and plan the repairs that will help stop the next visit.