By Benjamin Brand
Geographic Range
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.
Habitat
(262.4 to 6232 ft)
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.
These animals are found in the following types of habitat:
terrestrial 
.
Physical Description
(0.21 to 0.46 oz; avg. 0.33 oz)
(2.13 to 5.75 in; avg. 4.57 in)
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.
Some key physical features:
endothermic ; bilateral symmetry .
Reproduction
Females give birth year round
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
Key reproductive features:
iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; viviparous .
Food Habits
Reithrodontomys montanus often stores food underground for use during severe winters. It eats: seeds, flowers, grasses, cactus fruits, and insects such as grasshoppers.
Primary Diet:
omnivore .
Animal Foods:
insects.
Plant Foods:
seeds, grains, and nuts; fruit; flowers.
Foraging Behaviors:
stores or caches food .
Ecosystem Roles
Reithrodontomys montanus is often found in association with many other rodents, however it is usually the least abundant in its communities.
Key ways these animals impact their ecosystem:
disperses seeds.
Conservation Status
This species is considered common.
Other Comments
This species was first discovered by Baird in 1855. The discovery was made in a mountainous region of Colorado which led to the species montanus. Later, however, its distribution was found to be the Great Plains, far from any mountains.
For More Information
Find Reithrodontomys montanus information at
Contributors
Benjamin Brand (author), University of Michigan.
Bret Weinstein (editor), University of Michigan.
