The Pacific jumping mouse can reach a maximum age of at least four years in the wild. Behavior The Pacific jumping mouse is nervous and high strung, and may become aggressive when trapped, biting the hand of the trapper. Despite this, it is believed to be naturally gentle. When fighting, it produces a squeaking noise and vibrates its tail against the substrate rapidly to produce a drumming noise. Zapus trinotatus also jumps wildly from side to side when irritated.
Infants produce a high-pitched squeal.
When escaping predators, it can leap upward 90-180 cm, turn its head downward, arch its back, dive to the ground, and prepare to jump again. Alternately, it may remain motionless when a predator is detected, relying on its pelage as camouflage, and move to dense cover when the danger passes. The Pacific jumping mouse is nocturnal and crepuscular. When eating, it seizes food in its forepaws, sits back on haunches, and nibbles on its food. This nest is spherical, woven of grass, and approximately 100mm in diameter.