Zapus princeps
western jumping mouse

Western jumping mice are found throughout western Canada and much of the western United States.

(Knopf 2000)

Western jumping mice are found primarily in moist fields, thickets, and woodlands, especially where grasses, sedges, or other green plant cover is dense. They are also found in grassy edges of streams, ponds, and lakes, usually within 50 meters of water.

(Knopf 2000)

Western jumping mice have yellow sides with a dark band down the middle of their back. Their belly is usually white, but can sometimes have a yellow tinge. The body length including the tail is 215-260 mm. They have a long tail (126-160 mm) that is darker on the top than the bottom. Males and females are similar in size and characteristics. Weight ranges from 18 to 24 grams, but can reach up to 35 grams before they enter hibernation. The hind feet are very large with each foot measuring 28-34 mm and they can hop up to 2 m. Each upper tooth row has 4 molariform teeth with the first reduced in size.

(Knopf 2000)

Little is known about mating behavior in Z. princeps.

The timing of reproduction for Western jumping mice varies from year to year. Many females less than 2 years old do not breed. If they do breed it will usually occur later in the season and they produce smaller litter sizes than older females.

Western jumping mice mate soon after they emerge from hibernation, usually in June. Their gestation period is approximately 18 days and they give birth to 3 to 9 young. A newborn weighs about 1 gram. They can have 2 or 3 litters per year but will usually have only one litter. Young born too late in the year do not acquire sufficient fat reserves to survive hibernation.

The young are born in a well-developed spherical nest 15-20 cm in diameter with no obvious entrance. The nest is interwoven with broad-leaved grasses, sedges, and other plant fibers, and located in a depression in the ground usually less than 30 cm below the soil surface.

(Falk et. al. 1987, Brown 1967)

Young are born helpless and are cared for in the nest by their mother until weaned.

Western jumping mice can live as long as 6 years if they survive their first season of hibernation. Half of all juveniles that enter their first winter hibernation will die. Because Western jumping mice hibernate they are only active for a short period each year.

(Meyers 1969)

Western jumping mice are primarily nocturnal, however they will also forage in the daytime. They live in burrows dug by themselves or other animals. Fat deposition begins 1 month prior to hibernation. When alarmed, Western jumping mice will drum their tails on the ground. If startled from their hiding place, they may make a series of jumps 90–150 cm long, disappearing by remaining motionless in a new spot. They tend to use the runways of other animals rather than making their own. They can swim and climb. Little is known about the social behavior of these animals.

(Belk et. al. 1988)

Western jumping mice need high-energy foods to increase fat storage for their long hibernation periods. The main foods eaten by Western jumping mice are arthropods, seeds and leaves. Seeds are important in the fat deposition, however, arthropods may be a critical substitute when seeds are not available.

(Vaughan et. al. 1980)

Western jumping mice exhibit low predation by mammalian carnivores during hibernation. One of the reasons for this is that their hibernation chambers are hidden far beneath the layers of snow. Also, jumping mice give off little odor during hibernation, making them difficult find.

(Brown 1970)

Western jumping mice are important prey species for many predators in the ecosystems in which they live. They are also important as consumers of seeds and arthropods.

Z. princeps is an important component of healthy grass-dominated habitats throughout their range.

Western jumping mice are common within their range.

The family name was changed in 1996 from Dipodidae to Zapodidae.