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The Difference Between Rats and Mice


The Difference Between Rats and Mice

Mice and rats are the animals most commonly used in lab tests.


Besides the differences in their physical characteristics, rats and mice are significantly different in many other ways. Because rodent control efforts will be most successful when based on an understanding of the pest itself, it is important to know the differences between these two rodents.

For example, one of the most critical differences in behavior between mice and rats are that of curiosity vs. caution.

The rat is very cautious and will not readily approach new items in its path until it has had time to get used to its presence. Thus, prior to setting rat traps, unset traps should be placed in the rat's path.

Mice, on the other hand, are very curious and will investigate new things. Thus, if mice are not caught within the first days of trap placement (using set traps), the trap is likely in the wrong place and should be moved.

Other differences include:


Living and Breeding

  • Mice prefer cereal grains and plants, but will feed on almost anything.
  • Although they rarely burrow, they will nest in hidden areas near a food source.
  • A mouse will build its nest from about any soft material or finely shredded paper.
  • In a single year, one female mouse can breed up to 10 litters of 5 to 6 young.
  • These 60 offspring can begin to reproduce themselves in as little as six weeks.
  • Mice have an average lifespan of 9 to 12 months.


  • When eating, fighting, or orienting itself, the mouse will stand up on its hind legs, supported by its tail.
  • As excellent jumpers, swimmers, and climbers, mice can ascend even rough, vertical surfaces.
  • They are fast runners, moving on all fours and holding the tail straight upright for balance -- unless frightened.
  • A nocturnal creature, the mouse is most active from dusk up 'til morning light. Mice are generally averse to bright lights, but one may sometimes be seen during the day, particularly if its nest has been disturbed or it is seeking food.
  • A mouse can slip through 1/4-inch holes and gaps - much smaller than appears possible.
  • It can jump 13 inches high from a floor or other surface, and can run along wires, cables, and ropes.

Mouse Facts

  • The House Mouse has been designated as one of the top 100 "World's Worst" Invaders.
  • Mice are afraid of rats, which often kill and eat mice. For this reason rat odor is stressful to mice and will affect their behavior and reproduction.
  • Mice, themselves, have an inherent musky odor.
  • Though color blind, mice have very keen sense of hearing, smell, taste, and touch
  • They can be found indoors and outdoors, in urban and rural areas.
  • Droppings, gnawing and tracks are signs of a mouse infestation.


Living and Breeding

  • Rats will eat nearly anything, but they prefer fresh grain and meat.
  • Rats require at least 1/2 to 1 ounce of fluid each day. If this is not attained through
  • moisture in foods that it eats, the rat must have water to drink.
  • Rats will burrow under buildings, along fences and railroad tracks, and under vegetation and debris.
  • A female rat can have six litters of up to 12 young per year. These more than 70 rats can begin breeding themselves within three months of birth.
  • Spring is the most active season for rat breeding.
  • Rats can live up to a year and a half.


  • Rats can enter a building through a gap as small as 1/2 inch in diameter.
  • Strong swimmers, rats will live in sewers and can enter buildings through broken drains or toilets.
  • It will climb in order to access food, water, or shelter.
  • Rats will set and follow standard routines and pathways. If new objects are set in a path, they will painstakingly avoid it.
  • Rats tend to stay within 300 feet of their nest or burrow.

Rat Facts

  • Signs of rat presence include droppings, gnawing, tracks, runways and burrows.
  • Being nocturnal, rats have very poor eyesight, rats have a very strong sense of small, taste and hearing.
  • Rats can be distinguished from mice by physical characteristics, primarily their larger size and, coarse fur, and proportionately larger head and feet.
  • The two dominant rat species in the U.S. are the Norway and the roof rat. The two breeds do not get along, and will fight each other to the death - with the Norway generally overpowering the roof rat.
  • However, because the Norway rat tends to reside in lower floors of buildings and roof rats in the upper floors, they can both infest the same building at one time.

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