House mice didn’t evolve in Illinois forests or prairies at all. They arrived from Central Asia centuries ago, hitching rides with grain shipments and early farms, and the state’s own conservation trackers list the species as exotic rather than native. NatureServe doesn’t even assign it a rarity rank here; its status reads Not Applicable, the record keeping way of saying the usual check doesn’t apply to an animal that was never part of Illinois’s original wildlife.
The state carries a modest record set for this mouse, just 190 entries logged statewide, with reports clustered at Cook County forest preserves, Midewin National Tallgrass Prairie, and along the Des Plaines River corridor. Those are places people happened to look, not a map of where the mouse actually lives; it’s just as content behind a barn wall or under a kitchen floor as in a grassy preserve.
Reports peak in November, with October and September close behind, though that pattern likely tracks when people notice mice moving indoors for winter more than any real shift in how many are out there.
Full species profile
