The deer mouse’s body is about three to four inches long. Its back has brown fur with a dark stripe down the middle. The belly and feet have white fur. Its ears are dark brown with white edges. The tail has dark hairs on the top and white ones on the underside. The tail is about as long as the head-body length. This mouse has small back feet. The eyes are large.
The deer mouse may be found statewide in Illinois. It lives in grasslands, prairies, pastures, barren ﬁelds and stubble ﬁelds. This rodent is an omnivore that eats insects and the seeds of native and farm plants like corn, soybeans and wheat. It constructs a shallow burrow system or may use the burrows of other small mammals. Family groups are often found in burrows. Breeding occurs year round, and young are born throughout the year. Because this mouse has a short life span, a female rarely gives birth to more than two litters. Litter size ranges from one to nine with an average of about ﬁve. Young are born helpless but are ready to live on their own in about four weeks.