Zapus hudsonius (Zimmermann, 1780)

Jumping mice are profound hibernators and are often found torpid when live-trapping in the fall. (Photo by Brian Lawhead)

Species diagnosis

General Characteristics

• Tail at least 1½ times length of head and body, naked and scaly
• hind feet enlarged, generally greater than 25% of head and body length
• infraorbital foramen enlarged, larger than zygomatic plate  
• four upper cheek teeth (rarely three)
• Skull small, basal length averaging less than 20mm
• Length of maxillary tooth row ageraging less than 3.7mm
• Incisive foramina averaging less than 4.6mm

Alaska subspecies