Geographic Distribution of the Pocket Mouse, Perognathus fasciatus

The pocket mouse Perognathus fasciatus has long fascinated naturalists, who traced its range across the northern Great Plains and the Rocky Mountain foothills. Early 20th‑century surveys identified a handful of geographic races, but the picture remained fragmentary. This work revisits those foundations, laying out the known distribution as a stepping stone for fresh inquiry.

Drawing on thirteen newly examined specimens from northwestern Nebraska, the author compares them with material from the species’ entire range. The study reveals a subtle colour gradient—from darker tones in the northeast to paler hues in the southwest—and proposes a re‑classification that reduces the once‑separate species P. callistus to a subspecies of fasciatus. Five distinct subspecies emerge, each distinguished primarily by pelage colour, with only modest skull differences among most groups.

Accompanying maps and seven detailed figures illustrate the revised boundaries, while acknowledgments highlight the collaborative effort of museums and researchers nationwide. By clarifying the taxonomy and distribution of these small rodents, the study provides a valuable reference for ecologists, conservationists, and anyone curious about the hidden diversity of the plains.