Illinois sits at the far northern edge of the cotton mouse’s range, and NatureServe now lists the state’s population as presumed extirpated, meaning it’s likely gone from Illinois even though the species remains numerous across the Southeast. Illinois has no cotton mouse records from 2000 through 2026, which fits a population that may no longer exist.
With no recent records, there’s no seasonal pattern to describe, and this large-footed, nocturnal mouse is easy to mistake for other Peromyscus deer mice in any case.
The species is still classified as native to Illinois rather than introduced, a status that reflects its documented history in the state rather than a current, confirmed presence. Anyone hoping to find a cotton mouse in Illinois today would be looking for a species the record book already treats as functionally gone.
Full species profile
