|Western Harvest Mouse
Reithrodontomys megalotis (Baird)
Color photo by Barbara L. Clauson.
Description: The western harvest mouse is a small and dainty mammal which can be distinguished from other members of its family by: 1) tail that is as long as the head and body, 2) fur that is soft, relatively long, and colored brown with black guard hairs on upperparts, 3) white underparts and feet, 4) tail with broad dark stripe on top and white underneath, and 5) upper incisors that possess a single groove on the outer surface. For distinctions between the western harvest mouse and the very similar plains harvest mouse, see the account of that species. Young have duller fur, and the sexes are alike.
Size: Adults may attain the following dimensions: total length 118-156 mm; tail 55-77 mm; hind foot 14-20 mm; ear 10-16 mm; weight 11.5-16 grams.
Range and Habitat: Two subspecies occur in Kansas, Reithrodontomys megalotis dychei in the northern half of the state and Reithrodontomys megalotis aztecus in the southwestern section of the state. This species inhabits a fairly wide variety of habitats, from relatively dry grasslands and dense weedy fields with high overhead protection where the ground surface between plants is generally bare, to brushy riparian areas. However, the grass is usually taller and denser than that inhabited by the plains harvest mouse.
Reproduction: The western harvest mouse breeds throughout the year except during severe winter months. From two to nine young (average four to five) are born blind, naked and hairless, after a gestation period of 24 days. In ten days the eyes and ears open, and hair has already started to grow on the body. In 19 to 21 days the young are weaned and in five weeks they are adult size. The young usually breed at an age of two months, but in some cases earlier. Females have six nipples, one pair near the front legs (pectoral) and two pair in the groin (inguinal) region.
Habits: Although the western harvest mouse does not often develop its own runways, it does use those made by other small mammals, especially prairie voles. It is mainly nocturnal, but is active during cloudy days, in areas of dense vegetation. Its nest is placed on the ground or above ground in grasses, weeds or low shrubs and other vegetation. The nest is about three inches in diameter, round, compact, and woven with dry grasses and plant fibers. It is lined with soft plant material, such as thistledown. Like other harvest mice, they are socially tolerant, and may huddle in communal nests, especially in winter.
Food: This mouse eats seeds, green plant parts, and some insects.
Remarks: The western harvest mouse is preyed upon by hawks and owls, small carnivores and snakes. Longevity in this mouse is about one year or less.
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