What's the difference between rats and mice?

Rats and mice are both a part of the rodent family and, on the surface, they have similarities in appearance. However, there are certainly not the same. The differences between rats and mice mean different treatments for each. It’s important for you to know which rodent you have infesting your home or property.

There are just two species of rats and one species of mice that have become the most common pests in homes and businesses, and this is due to their ability to adapt to the human environment. These are:

• The brown rat (Rattus norvegicus, also called the common or Norway rat)
• The black rat (Rattus rattus, also called the roof rat)
• The house mouse (Mus domesticus)

The house mouse has several subspecies that are common in different parts of the world and are increasingly being recognised as separate species, but these are all virtually indistinguishable from each other.

All rodents have the common identifying feature of a pair of incisor teeth in the upper jaw. They tend to have short legs and a long tail, but a closer look at their body characteristics and habits show that they have easily distinguishable features that you can use to identify their differences.

The easiest distinguishing feature is the small size of the house mouse at 3-10 cm long.

However, a mouse can be confused with a young rat.

• A mature mouse can be distinguished from a young rat by its larger ears and longer tail compared to its body length than the rat
• A young rat also has distinctly larger feet and head compared to the body than a mouse
• Mice are usually light grey or brown in colour with a lighter shade on their bellies

The brown rat is larger than the black rat and they have the following differing body features:

• Thicker body
• Tail shorter than length of head & body
• Paler colour underneath the tail
• Small hairy ears
• Blunt nose

Physical appearance of black rats:

• Slender body
• Large thin ears
• Pointed nose
• Tail longer than head & body

Both rats and mice are omnivorous but the brown rat and house mouse prefer cereals, while black rats prefer fruit and foods with a high moisture content.

• Prefers cereals
• Cuts grain when eating, giving the appearance that is has been chopped
• Tends to seek food in the same places, making baiting easier
• Drinks about 60ml water a day

• Prefers moist fruit and vegetables
• Cuts grain when eating, giving the appearance that is has been chopped
• Tends not to eat at the same location on consecutive nights. This makes them more difficult to control, requiring many small baiting points using moist food, which only remains edible for a few days before needing replacing
• Drinks about 30ml water a day

• Prefers cereals and flour and wheat based foods, such as bread
• When eating it ‘kibbles’ the grain by removing the outer husk to eat the white endosperm inside
• Tends to seek food in the same places
• Doesn’t need to drink water but will drink about 3ml if available

Rats and mice live in a variety of areas, they can survive well in the inside and an outside environment.

• Usually lives on the ground and burrows. It occurs throughout buildings, in sewer systems and outdoors
• Their burrowing can cause extensive damage to the sewers
• Brown rat tends to walk on the pads of their feet and the surfaces that it travels along show continuous smudges from their oily fur

• Black rats are mainly restricted to buildings
• They are agile and a good climbers, nesting high up under roofs
• In warmer countries, where they originate, black rats will nest in trees, especially in woodland and orchards
• Black rats tend to walk on their toes and the surfaces that the ship rat travels along show separated smudges

• Usually lives on the ground and nests in burrows, but is agile and can climb
• In heavy infestations, grease from the body combined with dirt and urine can build into small pillars
• A mouse has smaller footprint than a rat

The droppings of the three animals differ in size and shape, according to the body size. Rat droppings can often been mistaken for mouse droppings and those from a cockroach.

Brown rat droppings are wide and are dark brown colour. They are typically found in a tapered, spindle shape – resembling a large grain of rice.

Black rat droppings are long and thin, and are smaller than brown rat droppings. Black rat droppings are more regular in form with a banana like curve and pointed ends.

Mouse droppings are approximately 3-8mm in length, and are often found scattered randomly during a infestation. Mouse droppings are granular in shape and black in colour and can be found near nesting areas.

Mice reach sexual maturity earlier and produce larger litters at a more frequent rate than rats. The new borne of all three rodents are blind, hairless and completely dependent on the mother for feeding and protection.

• Litter size: 7-8
• Number of litters per year: 3-6
• Time to maturity: 10-12 weeks

• Litter size: 5-10
• Number of litters per year: 3-6
• Time to maturity: 7-8 weeks

• Litter size: 4-16
• Number of litters per year: 7-8
• Maturity: 8-12 weeks

If you think that you have mice or rats in your home or business, contact the experts in rodent control and prevention available at Rentokil.