Indiana marks the eastern edge of the western harvest mouse’s range, and the state’s records read like the story of one well-worked wetland. Thirty-eight of 48 reports come from Newton County, nearly all of them at Willow Slough Fish and Wildlife Area, a big prairie-wetland restoration in the northwest corner of the state. A few more come from neighboring Tippecanoe and Lake counties.
The March peak in the record 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 remaining strongholds like Willow Slough and Kankakee Sands carry outsized weight. Whether it persists elsewhere in Indiana is exactly the kind of question a record this thin can’t answer.
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