You can usually tell mice from rats by the size and shape of their droppings. Mouse droppings are small, with a spindle or uneven shape. Rat droppings are much bigger, and their shape tells you which rat it is. The Victorian Department of Health rodent technical note says the brown rat leaves banana or sausage shaped droppings, while the roof rat leaves oval or spindle shaped ones.
The three pest rodents in Australian homes
Australia has more than 60 native rodent species, but only three introduced pest species, brought here from overseas, move into houses:
- House mouse. A small, slender animal with a pointed nose and large ears.
- Brown rat. Also called the Norway rat or sewer rat. It is the larger of the two pest rats, with a heavy body and a blunt nose.
- Black rat. Also called the roof rat or ship rat. It is slimmer, with a pointed nose and a very long tail.
How to read the droppings
Size. Mouse droppings are tiny. Rat droppings are clearly larger, so big droppings almost always mean rats.
Shape. The Victorian technical note gives these shapes:
- House mouse: small, spindle or uneven shaped droppings.
- Roof rat: oval or spindle shaped droppings.
- Brown rat: banana or sausage shaped droppings.
Freshness. The ACT Government rats and mice guide says to look for black, moist, thin droppings. Fresh droppings mean the animals are active now. Dry, crumbly droppings are usually older.
Take a photo of the droppings next to a coin. The coin shows their real size.
Other clues: body, tail, ears and snout
If you see the animal, check these features:
- Weight. The ACT Government lists a house mouse at about 15 g, a black rat at about 260 g, and a brown rat at about 450 g.
- Tail. A house mouse is about 7.5 cm long with a tail of about 8 cm. A black rat's tail is usually longer than its head and body together. A brown rat's tail is usually shorter than its head and body.
- Snout and ears. Mice and black rats have pointed noses and large ears. Brown rats have a blunt nose and small ears.
The Victorian note also says mice nibble the outside of grains and leave the core, while rats leave crumbs or small pieces. Mice gnaw holes up to 20 mm wide. Rat holes are larger, about 80 mm wide, and can lead to a nest.
Where you find droppings, and what it tells you
In the kitchen and pantry. House mice tend to live inside buildings. The ACT Government says rodents shelter behind or under fridges, dishwashers and cupboards. Many tiny droppings in a pantry, cutlery drawer or under the sink usually point to mice. Campsie has a busy food strip along Beamish Street, with homes on the streets around it, so if you keep finding small droppings in a kitchen there, book rodent control in Campsie and show the technician where they appear.
In the roof or ceiling. Roof rats are good climbers and nest in roof voids, the empty space above the ceiling. Night-time scratching in the ceiling, plus larger spindle shaped droppings near the manhole, usually means roof rats. East Hills sits on the Georges River, and tall trees with branches over the roof can give rats a path up, so if those night sounds start in an East Hills home, arrange quick rodent control in East Hills before they settle in.
In the garage, shed or yard. Brown rats dig well. The ACT Government lists burrow holes around buildings, fences and concrete slabs as a sign of rodents, along with worn paths and greasy marks along walls. Greenacre sits beside the Chullora industrial area, and a Greenacre garage with thick, sausage shaped droppings and a hole beside the slab needs urgent rodent control in Greenacre to deal with brown rats.
The ACT Government notes that seeing a rodent in the daytime often means there are many of them, or a good food supply nearby.
Clean up droppings safely
The NSW Health mouse plague fact sheet says the bacteria behind leptospirosis, an infection that can cause fever and headache, can be found in mouse and rat urine. These infections are rare. Wear gloves, then mop floors and clean benches with a disinfectant or bleach solution, as NSW Health suggests. Wash bedding or clothes that touched droppings in hot water.
Rat or possum in the roof?
Roof noises are not always rats. Brush-tailed possums also like roof cavities, and the key difference is size. The NSW Environment guide to possums in your roof says possums are about the size of a cat. A rat is far smaller and has a long, thin tail, while a possum has a thick, bushy tail.
NSW Environment suggests two simple checks:
- Watch the roof line at dusk, when a possum leaves to find food.
- Sprinkle flour near the spot where you think the animal gets in, then check the footprints the next morning.
Possums are protected in NSW under the Biodiversity Conservation Act 2016. It is illegal to kill or relocate a possum, or to trap one without a licence. So it matters to know which animal you have first.
Picnic Point backs onto Georges River National Park, so bushland and its wildlife sit close to many homes there. If the flour shows small rat prints rather than cat-sized ones, book rodent control in Picnic Point and mention the noises you heard.
What to note before you book
Write down:
- Where you found the droppings, and whether they were fresh or dry.
- Their size and shape, with a photo next to a coin.
- Any noises, and what time of night you heard them.
- Chew marks or holes, and roughly how wide they are.
- Whether there are children or pets in the home.
Send these notes when you contact our team for professional pest control in Bankstown, and you will get clear next steps.