The wandering garter snake (Thamnophis elegans vagrans) and short-horned lizard (Phrynosoma douglassi brevirostre)are the only reptiles documented.
The monument's sagebrush steppe landscape appears ideal habitat for rattlesnakes, but they are not found here. Why? We don't know. Prairie rattlesnakes inhabit other parts of Wyoming at elevations over 8500 feet, but usually are restricted to elevations less than 7,000 feet.