Geographic Distribution of the Pocket Mouse, Perognathus fasciatus

The study opens with a careful review of early 20‑century classifications of the pocket mouse, Perognathus fasciatus, and quickly shows how new field collections have upended those old ideas. By examining dozens of specimens from Nebraska, Wyoming, Montana and surrounding states, the author discovers a previously unrecognized subspecies and reassigns a once‑full species to subspecific rank. Color patterns that shift from dark in the northeast to pale in the southwest provide the most obvious clues, while subtle skull differences help fine‑tune the taxonomy.

Accompanied by seven detailed figures, including a distribution map that pins the range of each of the five recognized subspecies, the work offers a clear visual guide for researchers and enthusiasts alike. The collaborative effort draws on material loaned from major natural history museums across North America, highlighting the breadth of the investigation. Readers come away with a nuanced picture of how geography, genetics and environment intertwine to shape a modest yet ecologically important rodent.