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Mouse or Rat? What's the Difference Anyway?

Unless you keep them as pets, the sight of a mouse or rat in your home is probably very unexpected. And while we may lump mice and rats together as nuisance animals, they are different. Plus not all mice and rats are nuisance animals that invade our homes.

A mouse (left) and a rat. (Photos via Shutterstock)

The mice and rats many people are most familiar with because they do sometimes make their way inside our homes are house mice and Norway rats, or brown rats. These species were introduced from Europe and are not native to the United States. Illinois is also home to other mice and rat species that are native to the area, including the deer mouse, white-footed mouse, eastern woodrat and a few others that are less common.

The eastern woodrat is state endangered and only found in seven counties in the southern part of Illinois. The deer mouse and white-footed mouse are common across the state. Because they are native, all three are beneficial to the ecosystem. In addition, they all serve as an important food source for animals higher up the food chain, including coyotes, foxes, hawks and owls.

One main difference between mice and rats generally is that rats are quite a bit larger than mice. This is true of house mice and Norway rats. House mice are typically between 5 inches and 7 inches long, including the length of their tails. Norway rats can be up to three times as long, between 12 inches and 18 inches long including their tail length.

Our native mice and rat species fit this mold as well. Eastern woodrats are similar in size to Norway rats. Similarly, white-footed mice and deer mice are about the same size as house mice, with both generally between 6 1/2 inches and 7 inches long.


Words to know

Distinction: A difference or contrast between similar things.

Nuisance: Something that causes an inconvenience or an annoyance.


White-footed mice and deer mice can be hard to distinguish from one another because they are similar in size and appearance. They both have grayish-brown or reddish-brown fur with large ears and large black eyes. One difference between them is that white-footed mice tend to look larger because they have longer tails, usually about half the length of their bodies. Deer mice have tails usually closer to one-third of their body length, sometimes longer.

Another key distinction between mice and rats generally is the shape of their snout. Mice tend to have pointier, more triangular-shaped noses, while rat noses tend to be flatter and more blunt. And while rat tails are usually long and hairless, many mice species have at least some short hair on their tails.

A house mouse, for example, has a gray tail that is mostly hairless. Deer mice have tails that are dark on the top and white on the bottom, while white-footed mice have pale-colored tails that are the same color on the top and bottom.

Our nuisance mice and rats can be found almost anywhere there are buildings to invade, but rats are more common in urban, city settings. House mice typically live in agricultural fields and open areas. Our native mice species have different preferred habitats. Deer mice are commonly found in open areas like pastures and fields, and white-footed mice most often live in forest edges. Neither is as good at entering our homes and buildings as the house mouse, but white-footed mice will sometimes seek shelter in homes near wooded areas.

All our local mice and rats, including the non-native species, eat a varied diet of both animal and plant matter, including insects, seeds, nuts and fruits. When they become nuisances in our homes, mice and rats will eat virtually any food they can easily get to, including accessible human and pet foods.


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