Indiana marks the eastern edge of the western harvest mouse’s range, and the state has no records of it from 2000 to 2026. Older specimen records, all outside that window, read like the story of one well-worked wetland: most come from Newton County in the northwest corner, home to the big prairie-wetland restoration at Willow Slough Fish and Wildlife Area, with a few more from Tippecanoe and Lake counties.
Those old specimens bunch in March, which looks odd until you think about method: small-mammal trapping in restored grassland often runs early in the year, before the vegetation grows tall enough to hide a trap line. An October bump tells the same story from the other end of the growing season. Neither is a population signal.
NatureServe ranks the species S3, vulnerable, in Indiana. The mouse depends on dense, grassy cover, a habitat the state has largely converted to farmland, so the northwest’s remaining prairie wetlands, like Willow Slough and Kankakee Sands, carry outsized weight. Whether it persists in Indiana at all is exactly the kind of question an empty recent record can’t answer.
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