Montane harvest mice live in the dry uplands of the Great Plains. They are found in southwestern South Dakota and southeastern Montana south thruough eastern Wyoming, Colorado, and New Mexico, all of Nebraska and Kansa and most of Oklahoma and Texas. Also found in southern Arizona and northern Mexico in the extremes of its range.

Biogeographic Regions: nearctic (Native )

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

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (20,000-2,500,000 square km (about 8000-1,000,000 square miles)) Missouri River west and south to the Rockies, and from western South Dakota south to southeastern Arizona, Mexico (Sonora, Chihuahua, and Durango), and Texas. Elevational range: from about 84 m in Texas to at least 1700 m in Colorado, 1920 m in Mexico.

Reithrodontomys montanus is a small mouse with grayish-brown fur. It has a white underside and a dark stripe down the middle of the back. The tail of this species ranges from 20 to 69 mm and is always shorter than the head and body. The tail is also striped and has sparse fur, yet does not appear scaly. Reithrodontomys means "groove toothed mouse" and refers to a groove that is found in the upper incisors. This groove easily distinguishes this genus from others occuring in the same area.

Range mass: 6 to 13 g.

Range length: 54 to 146 mm.

Average length: 116 mm.

Length: 14 cm

Weight: 10 grams

See Hoofer et al. (1999) for information on discrimination between R. MEGALOTIS and R. MONTANUS using cranial characters.

• Terrestrial

These mice appear to prefer climax, or nearly climax, well-drained grassland. They are in the highest densities in shorter grasses, but are found in lower numbers in taller grasses. Reithrodontomys montanus builds its nest out of grasses and places the nest slightly above the ground in grasses or shrubs, or on the ground. The species has also been known to take over a bird's nest for its own. In areas with human contact Reithrodontomys montanus has been found in tin cans or other suitable nests.

Range elevation: 80 to 1900 m.

Habitat Regions: terrestrial

Comments: Well-developed grasslands. Occupies areas with less than 50 percent bare soil (Oklahoma); weedy situations. Old hayfields, highway medians, cultivated fields (wheat, sorghum), grazed riparian woodland. Also desertscrub and chaparral (Hoffmeister 1986). May nest in grass on or above ground, in underground burrow, beneath rock in stony pasture, under log or discarded lumber, or in can or other object on or near ground (Wilkins 1986).

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.

Reithrodontomys montanus often stores food underground for use during severe winters. It eats: seeds, flowers, grasses, cactus fruits, and insects such as grasshoppers.

Animal Foods: insects

Plant Foods: seeds, grains, and nuts; fruit; flowers

Foraging Behavior: stores or caches food

Primary Diet: omnivore

Comments: Bulk of diet in Kansas consists of grasshoppers and grass seeds (Wilkins 1986).

Reithrodontomys montanus is often found in association with many other rodents, however it is usually the least abundant in its communities.

Ecosystem Impact: disperses seeds

Known Predators:

• numerous mammalian carnivores (Carnivora)
• snakes (Serpentes)
• raptors (Falconiformes)
• barn owls (Tyto alba)

Seldom abundant; usually fewer than 10 per 1000 trapnights. Home range estimates range from about 0.04 to 0.84 ha, with individual movements of up to 185 m over 5 months (Wilkins 1986).

Females have 6 mammae. Males have seminal vesicals, preputial glands, ampullary glands, penial spines, and a baculum.  Young are born naked and blind. They are well haired at 6 days and their eyes open at 8 to 13 days. Adult size is reached in 5 weeks. Reithrodontomys montanus goes through 2 changes in pelage before reaching adulthood. The juvenile hair is cottony and duller in color. Sub-adult pelage is the same color as adults but the hair is less dense. Males reach sexual maturity at 2 months, while females reach sexual maturity at about 12 weeks

Breeding season: Females give birth year round

Range number of offspring: 1 to 9.

Average number of offspring: 4.

Average gestation period: 21 days.

Average weaning age: 21 days.

Range age at sexual or reproductive maturity (female): 8 to 12 weeks.

Range age at sexual or reproductive maturity (male): 8 to 12 weeks.

Key Reproductive Features: iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); fertilization ; viviparous

Parental Investment: altricial

Breeds February-November in north, probably all year in south. At least 2 litters (of 1-9, average 3/litter) are produced annually. Gestation lasts 21-22 days. Young are weaned at 2 weeks. A captive produced her 1st litter at 12 weeks; 3-4 weeks between successive litters.

This species is considered common.

IUCN Red List of Threatened Species: least concern

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

Global Protection: Unknown whether any occurrences are appropriately protected and managed

Comments: In an analysis of mitochondrial DNA, determined to be a sister species, but distinct from R. raviventris (Bell et al. 2001).