Zapus trinotatus lives in Canada and the USA. The range of Z. trinotatus is bordered from southwestern British Columbia to western Washington and Oregon to the Cascade-Sierra Nevada mountain chain through California to Marin County, California on the northern San Francisco Bay. (Gannon 1988, Wilson and Reeder 1993)

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: Southwestern British Columbia south through western Washington, coastal and west-central Oregon, along the humid coastal strip mostly west of the crest of the Cascade-Sierra Nevada chain through California to Point Reyes and Elk Valley, Marin County, California (Gannon 1988).

The length of the tail is 112-155mm, the hind foot is 30-36mm, the ear is 14-16mm, and the total length is 221-242mm. The pacific jumping mouse is larger than other members of the genus. The coarse pelage is strongly tricolored. It has a distinct separation of dorsal and ventral colors. The dorsum is dark brown, the sides are dark orange-brown and occasionally flecked with black, the ventrum is mostly white or diffused with dusky brown, and the chest often has a patch of buff that extends to the venter. Its tail is sparsely haired, has guard hairs, and is dark brown above and white below. The ears are fringed with the same color as the dorsum or light brown, and the tip of the ear is spade-shaped. The color of the pelage becomes paler in autumn.

The skull is broad and deep in proportion to length, the pterygoid fossa wide, the zygomatic arch widely bowed, and the mesopterygoid fossae narrow. The mandible has a wide and inflected angle, and the coronoid process is long, slender, and divergent from the condyloid process. The upper incisor is narrow and grooved in front. M1 and M2 have an isolated (free) paracone, and the first primary fold divides the occlusal pattern of M1. The lower M1 lacks an anteromedian fold in the anteroconid.

The dental formula is 1/1 0/0 1/0 3/3.

The posterior of the Pacific jumping mouse's body is heavier than the fore part. Zapus trinotatus is pentadactyl, and the soles of its feet are naked. Its hind legs are much longer than its forelegs. It has a small head which is slightly elongated, and its eyes are small and are located midway between its nose and its ears. The ears are short, but longer than the surrounding fur. There are four pairs of mammae on Z. trinotatus: one inguinal, one abdominal, and two pectoral mammae pairs. There are no cheekpouches.

The pacific jumping mouse has specializations for locomotion. It has well-developed hind legs, lengthened distal elements of hind limbs and digits, a shortened body, a lenthened tail, a shortened neck with increased cervical flexure, posterior shift of its center of gravity, a modified vertebral column to 39 vertebra, a and lengthened pseudosacrum. These traits help Z. trinotatus jump.

(Nowak 1991, Gannon 1988)

Length: 25 cm

• Terrestrial

Zapus trinotatus inhabits alder salmonberry, riparian alder, and skunk cabbage marsh ecosystems found among coastal redwood forests. In the northern part of its range, Z. trinotatus lives in dense forests, alpine meadows, and wet-grassy areas of the Olympic Peninsula and Cascade Mountains of Washington; and in moist meadows, marshy thickets, and woodland edges with ferns and a weedy understory. In the central part of its range (Oregon), Z. trinotatus lives in riparian-deciduous woodlands, wet meadows where the ground is peaty, and brushy redwood, Douglas fir, and mixed evergreen forests. In the south it occurs in the humus-filled dark soils of the Pacific coast in redwood forests with rushes, sedges, bracken fern, swordfern, Johnsongrass, poison hemlock, and monkey flower. Zapus trinotatus populations become more dense with increasing rain.

(Ganon 1988)

Terrestrial Biomes: forest

Comments: In alder and skunk cabbage riparian communities in redwood and Douglas-fir forests, alpine and other moist meadows, marshy thickets, brushy successional stages of coniferous and mixed forests; and to a lesser extent in lodegpole pine and Sitka spruce communities, and headland scrub and prairie (Gannon, in Wilson and Ruff 1999). Nests underground or concealed in vegetation on surface.

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.

Zapus trinotatus eats mainly seeds, but also fruit, berries, insects, fungi, mollusks, and fish. To get at the seeds it cuts plant stems and grass, and it leaves the remains in a neat pile. The Pacific jumping mouse forages at ground level, and it does not store food. (Gannon 1988, Niethammer 1990)

Comments: Feeds primarily on seeds (e.g., grasses, dock, and skunk cabbage). Also eats berries, insects, and some mosses and fungi. Rarely may consume bird eggs.

Populations density may fluctuate greatly from year to year. Predators include owls, weasels, skunks, and badgers.

Comments: Stores fat in late summer and hibernates around end of September. Emerges from hibernation in spring. Primarily nocturnal but also crepuscular.

Males become sexually active in May or June, and stay that way until September. Females are receptive in May and June. They give birth in July or August, with a gestation period of 18-23 days. There is one annual litter of 4-8 young. The altricial newborn is pink and hairless; its eyes are shut, its ears is folded, its head is short and stubby, and its facial vibrissae are not yet visable. This tiny newborn weighs .7-.9 grams. It is weaned after four weeks. It will become independent at around one month, and sexually mature the next year. The Pacific jumping mouse can reach a maximum age of at least four years in the wild. (Gannon 1988, Niethammer 1990)

Females are receptive in May or June, give birth usually in July or August. Gestation lasts about 18-23 days. Litter size is 3-8, usually 4-6. Young are independent in about 1 month, sexually mature in second calendar year (Maser et al. 1981, Gannon 1988).

The IUCN catagorizes the status of Z. trinotatus as indeterminate. Its habitat is decreasing because of grazing by livestock and introduced deer. (Wilson and Reeder 1993, Nowak 1991)

IUCN Red List of Threatened Species: least concern

Canada

Rounded National Status Rank: N4 - Apparently Secure

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

If numerous enough, Z. trinotatus can cause damage to meadows, though this is rare. (Ganon 1988)

Comments: Z. trinotatus and Z. princeps formerly were considered conspecific by some authors; they were regarded as separate species by Baker et al. (2003) and Holden and Musser (in Wilson and Reeder 2005).