The Western Jumping Mouse, somewhat like the Kangaroo Rat, has larger hind feet and smaller forefeet, which gives him a greater ability to spring into the air, using its extremely long tail for balance. Though he has only a 3 inch body, he has a 5-6 inch tail and has been seen jumping distances in excess of 5 feet! His coloring is quite plain, being dark grey or brown above and pale beneath, with coarse fur. Since he prefers a somewhat more humid climate in the mountains and meadows, the Western Jumping Mouse is more likely to be found in Bryce Canyon than Zion National Park. He prefers to live close to a source of fresh water and loves dense vegetation and plenty of aspen trees.
Most of the Western Jumping Mouse’s diet consists of seeds from various types of grass and herbs, though he will not turn down the occasional insect. A close observer of nature can always tell where a Weatern Jumping Mouse has been feeding by the tiny runways that are left as well as the grass stems whose seeds have been harvested and the tiny grass clippings that will be upon the ground. The nests will be built primarily from such grass clippings and are usually found underneath a log or inside a tussock.
As you might expect, the Western Jumping Mouse is nocturnal, which makes its primary enemies owls, weasels, racoons, skunks and bobcats. Its primary method of escape from such predators is its ability to make a series of zigzagging jumps across the meadows and fields until it finds a safe shelter. They are active only in the summer months, hibernating for as long as 8-10 months depending on the year and the exact location. Though they do awake about once each month during their long hibernation, they do not cache their food as you might expect, but rely solely on their fat reserves built up during the few months of summer. Unlike many mice, the Western Jumping Mouse does not make use of a burrow for daily shelter during its active summer months; but only uses a burrow for the purpose of hibernation.
Usually the Western Jumping Mouse only breeds once per year, about a week after awaking from hibernation, and bears a litter of 4-8, with a gestation period of 18 days. Their life span is about 3-4 years, and most Western Jumping Mice (roughly 60%) wait a full year before reproducing.