The Difference Between Rats and Mice and Why It Matters

A rat in a house

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If you have mice or rats, the methods to control them are not the same, especially roof rats that tend to live higher up. Your efforts to get rid of each of these house pests will be most successful when you understand their behavior, food preferences, and habitats. Read on to determine how to eliminate your rodent problem.


9 Key Differences Between Rats and Mice

Mouse vs. Rat Behavior

One of the most important differences in behavior between mice and rats is that mice are curious and rats are cautious.

  • Cautious rats: Rats are very careful and will choose to avoid new things in their path until they have had time to get used to them being there. Because of this, you need to place unset traps in the rat's path before putting set rat traps there.
  • Curious mice: Mice are very curious and will investigate anything new. So you have to do just the opposite for them: set the trap and put it right in its path. In fact, if you do not catch a mouse in the first few days, the trap is probably in the wrong place and should be moved.

Physical Characteristics

There are over 70 species of mice and rats widely distributed across North America. The house mouse (Mus musculus), Norway rat (Rattus norvegicus) and roof rat (Rattus rattus) species are in the Muridae family, which is the largest family of rodents and mammals in the world.

  • House mouse: Small head, small feet, pointed snout, large ears with some hair. These mice have a light brown body with some gray shading and a dark tail. Adults weigh 0.5 ounces (15 grams). The mice droppings are shaped like rods.
  • Norway rat: Heavy and thick body, blunt snout, and short ears with dark hair. These rats have a brown body with black shading and a shaggy coat. Their tails are dark on top and pale underneath. Adults weigh 11 ounces (300 grams). Their droppings are shaped like capsules.
  • Roof rat: Light and slender body, pointed snout, large ears with no hair. These rats have a gray body with black shading and a smooth coat and a dark tail. Adults weigh 7 ounces (200 grams). Their droppings are shaped like spindles.
Differences Between Rats and Mice

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Mice Habitat and Breeding

Mice prefer to eat cereal grains and plants, but they will feed on almost anything. A mouse will build its nest in a hidden area near a food source. It will use just about any soft material or finely shredded paper to build its nest.

In one year, one female mouse can breed up to eight litters of five to six babies, and these offspring can begin to reproduce in as little as six weeks. Mice usually live for about 12-18 months.

Mice Movement

Mice can stand up on their hind legs when supported by their tails. They do this to eat, fight, or figure out where they are. Mice are excellent jumpers, swimmers, and climbers. They can even climb up rough, vertical surfaces. They can jump 13 inches high and run along wires, cables, and ropes. Mice are fast runners. Moving on all four legs, they hold their tail up straight for balance. But if they are frightened, they will just run straight out.

Mice are nocturnal and most active from dusk until dawn. They do not like bright lights but will sometimes come out during the day looking for food or if their nest is disturbed. A mouse can slip through 1/4-inch holes and gaps.

Mice Facts

  • Mice are afraid of rats, because rats will kill and eat mice. Rat odor can be a strong deterrent to mice and affect their behavior.
  • Mice have a musky odor.
  • Mice are color blind, but their other senses — hearing, smell, taste, and touch — are sharp.
  • Mice can be found indoors and outdoors including cities and rural areas.
  • Signs of mice presence include droppings, gnawing marks, and tracks.

Rat Habitats and Breeding

Rats will eat nearly anything, but they prefer fresh grain and meat. Rats need 1/2 to one ounce of fluid each day. If rats do not get this in the food they eat, they have to find water. Unlike mice, which rarely burrow, rats will dig under buildings, along fences, and under plants and debris. The Norway rat lives mostly in burrows while the roof rat nests in walls, attics, and trees.

Per year, a female Norway rat can have seven litters of up to 12 young. These rats can start to breed by the time they are three months old. Rats breed primarily in the spring. Rats live for about two years in the wild. The roof rat has smaller litters of up to eight young and can have six litters per year.

Rat Movement

Rats can enter a building through a hole as small as 1/2 inch in diameter. They are strong swimmers, so, rats will live in sewers and can enter buildings through broken drains or toilets. A rat will climb to get to the food, water, or shelter. Rats follow regular routines and paths each day. If new objects are set in its path, it will do whatever it can to avoid it. Rats usually stay within 300 feet of their nest or burrow.

Rat Facts

  • Signs of a rat's presence are droppings, gnawing marks, tracks, runways, and burrows.
  • Like mice, rats are nocturnal and have very poor eyesight but have very strong senses of smell, taste, and hearing.
  • Compared to mice, rats are much larger, have coarser fur, and have proportionately larger heads and feet.
  • The most common rat species in the U.S. are the Norway rat and the roof rat. These two do not get along and will fight each other to the death. The larger Norway rat usually wins.
  • Norway rats tend to live in lower floors of buildings and roof rats will live on the upper floors, so they can both infest the same building at one time.
  • When are mice and rats most active?

    Both mice and rats are nocturnal creatures and are most active at nighttime.

  • How long do mice and rats live?

    Rats live longer than mice having an average lifespan of two years, while mice live about 12 to 18 months.

  • Should you have a professional exterminator get rid of mice and rats?

    There are some things you can do to get rid of a mice or rat infestation, but if you're not comfortable doing it, or if the infestation is out of control, let the professionals step in.