What is the difference between a rat and a mouse?

Only three species of rats and mice are some of the most common and essential pests in homes and businesses worldwide because of their ability to adapt very well to the human environment.

These include the brown rat (“Rattus norvegicus”, also known as the common rat or Norwegian rat), the house rat (“Rattus rattus”, also called the black rat, ship’s rat or roof rat) and the house mouse (“Mus domesticus”).

The house mouse has several subspecies, which frequently occur in various world areas and are now increasingly understood as an independent species. Still, in principle, they are all the same and can hardly be distinguished from one another.

All pests share the common feature of the two incisors in the upper jaw. In addition, they tend to have short legs and long tails. Still, a closer look at the characteristics of their bodies and behaviours reveals that there are easily distinguishable features that you can use to identify the pest invading your property.

What do mice look like?


The most accessible feature of a house mouse to recognise is its small size, 3-10 cm in length. However, a mouse can easily be mistaken for a young rat.

  • An adult mouse can distinguish a young rat by its more oversized ears and a longer tail than body length.
  • A young rat also has noticeably larger paws and a giant head compared to the body of a mouse.
  • Mice are usually light grey or brown, with more golden colour on the abdomen.

What do rats look like?

Brown Rat (Rattus norvegicus)

brown rat

  • thicker body
  • the tail is shorter than the head, + body combined
  • pale colour under the tail
  • small, hairy ears
  • blunt nose

Black rat (Rattus rattus)

black rat

  • slim body
  • big thin ears
  • pointy nose
  • the tail is longer than the head, and the body

Eating habits of rats and mice

Both rats and mice are omnivores, but the brown rat and house mouse prefer grains, and the house rat prefers fruits and foods with high moisture content.

House mice

  • prefer grain
  • when eating, they “grind” the grain by removing the outer skin of the grain and eating the endosperm in it
  • always look for food in the same place
  • do not need to drink water, but drink around 3ml when available

Brown rats

  • prefer grain
  • bite through grain as you eat it, making it look like it has been chopped up
  • always look for food in the same place, which makes it easier to use bait
  • drink about 60ml of water a day

House rats

  • prefer moist fruits
  • bite through grain as it eats, making it look like it has been chopped up
  • tend not to look for food in the same place – making them harder to catch and requiring lots of minor bait points with wet food that only stays edible for a few days before needing to be replaced
  • drink about 30ml of water a day

Where do rats and mice live?

Where do house mice live?

House mice usually live on the ground, as well as in nests in burrows. However, you are very flexible and can climb too. In severe infestation, the body fat combined with dirt and urine can form small columns. These sometimes survive prolonged periods and are therefore not necessarily an indication of a current infestation. A mouse naturally leaves smaller footprints than a rat.

Where do brown rats live?

Brown rats usually live on the ground and in holes in the background. They are spotted indoors, in the sewer system, and outdoors. The holes in the environment can cause substantial damage to the sewage system. The brown rat walks on the cushions of its paws, and the surface it walks over shows smear marks from its oily fur.

Where do house rats live?

House rats prefer to live in buildings at the harbour and on ships in temperate climates (hence the name “ship rat”). They are agile climbers and build their nests high up under the roofs. In warmer countries, house rats build their nests in trees, especially in forests and orchards. House rats tend to walk on tiptoe. The surfaces on which they show different traces of smear.

Identify faeces

The droppings of the three animals differ in size and shape, according to their body size. As a result, rat droppings are often confused with mouse or cockroach droppings.

House mouse droppings

The droppings of house mice are about 3-8mm long and are often found everywhere by chance during the infestation. The droppings are granular in shape, black, and can be located near the nest areas.

Brown rat droppings

The droppings of brown rats are wide and dark brown. It is usually conical to spindle-shaped – something like a large grain of rice.

House rat droppings

The droppings of house rats are long and thin, and it is also smaller than that of brown rats. In addition, House rat droppings are more evenly shaped – like a banana with pointed ends.


Mice reach sexual maturity earlier than rats and have larger litters and at shorter intervals. All newborns of the three rodents mentioned are blind, hairless and entirely dependent on the feeding and protection of their mother.

House mice

  • Litter size: 4-16
  • Litters per year: 7-8
  • Sexual maturity: 8-12 weeks

Brown rats

  • Litter size: 7-8
  • Litters per year: 3-6
  • Sexual maturity: after 10-12 weeks

House rats

  • Litter size: 5-10
  • Litters per year: 3-6
  • Sexual maturity: after 7-8 weeks

Are you infected with rodents such as mice or rats and need help combating them? Call us free of charge for a no-obligation consultation: Tel. +330 723-2515.