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

(Knopf 2000)

Biogeographic Regions: nearctic (Native )

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: Western North America. Southern Yukon to eastern North Dakota and northeastern South Dakota, south to east-central California, central Nevada, Utah, and north-central New Mexico (Hart et al. 2004).

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)

Range mass: 18 to 24 g.

Average mass: 0 g.

Range length: 215 to 260 mm.

Other Physical Features: endothermic ; bilateral symmetry

Length: 26 cm

Weight: 38 grams

• Terrestrial

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)

Habitat Regions: temperate ; terrestrial

Comments: Mountain meadows, marshes, along banks of streams and ponds, in dense cover of tall grasses and herbs. Nests in burrow in well-drained mound or elevated bank (Jones et al. 1983) or on surface among vegetation.

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

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)

Comments: In spring, feeds on insects and other invertebrates. By mid-summer, diet may shift to mostly grass seeds and small fruits.

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.

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)

Known Predators:

• owls (Strigiformes)
• bobcats (Lynx rufus)
• weasels (Mustela)
• skunks (Mephitinae)
• raccoons (Procyon lotor)
• gray foxes (Urocyon cinereoargenteus)

Primarily solitary. Home range in Utah averaged 0.2-0.6 ha in different areas in different years (Cranford 1983). Adult density was 8-32/ha in different areas.

Comments: Adults may enter hibernation September-October. Throughout winter, periods of hibernation alternate with arousal from torpor. In eastern Wyoming, emerges from hibernation mid-May to mid-June; may not emerge until late June or July at high elevations in Utah.

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)

Range lifespan

Status: wild: 6 (high) years.

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)

Breeding season: June through August.

Range number of offspring: 3 to 9.

Average gestation period: 18 days.

Average weaning age: 30 days.

Average age at sexual or reproductive maturity (female): 2 years.

Average age at sexual or reproductive maturity (male): 2 years.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); viviparous

Average birth mass: 0.8 g.

Average gestation period: 19 days.

Average number of offspring: 5.5.

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

Parental Investment: altricial ; female parental care

Breeds soon after females emerge from hibernation. Gestation lasts 18 days. Most young are born late June-early July. Apparently only 1 litter/year. Litter size estimated at 2-7 (average 5). Some females bear 1st litter at 1 year (Falk and Millar 1987).

Western jumping mice are common within their range.

US Migratory Bird Act: no special status

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: least concern

Canada

Rounded National Status Rank: N5 - Secure

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

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

Comments: Previously, Zapus hudsonius luteus was included in Z. princeps; Hafner et al. (1981) showed that luteus represents Zapus hudsonius.