Deer mice show up across a wide slice of Illinois habitat, from Shawnee National Forest’s hardwoods in the south to the Cook County preserves and Midewin’s restored prairie farther north. Few mammals in North America range this broadly or fit this many different landscapes, and Illinois’s spread of records reflects that flexibility rather than any single stronghold.
The 312 records logged since 2000 form two separate bumps, one in April and May and a second, sharper rise in October and November, with a clear lull through the summer. That pattern likely tracks the species’ spring and fall breeding pulses more than anything else, since deer mice can produce several litters a year outside the hottest months.
Records lean heavily on GBIF specimen data over iNaturalist photos, unsurprising for a mouse that’s notoriously easy to confuse with the white-footed mouse at a glance and usually needs a hand or a trap to identify with confidence. NatureServe rates the species secure across Illinois.
Full species profile
