ge. The young are weaned by 24 days. Young are reported to leave their natal nest around 3 weeks of age. (eNature.com, 2000; Ruff and Wilson, 1999; Webster and Jones Jr., 1982)
Females care for their young in a nest made of grass, nursing them for up to 24 days. The young are born blind and helpless, but grow quickly. The young can leave their natal nest as early as three weeks of age. Males apparently play no role in parental care. (Ruff and Wilson, 1999; Webster and Jones Jr., 1982)
This solitary mouse is nocturnal and mostly active before midnight. Activity is greater on moonless nights or rainy nights. They are sedentary, basing their activity at a nest, and using known runways. (Nowak, 1999; Ruff and Wilson, 1999; Webster and Jones Jr., 1982)is also territorial.
It is known that this mouse undergoes torpor when it meets cold temperatures; however, it is unknown if it undergoes true hibernation. (Royal British Columbia Museum, 1995)
Western harvest mice cache food in their nests, and use runways to navigate their environment. They are not opposed to using the runways of other species, such as Microtus and Sigmodon. (Nowak, 1999; Webster and Jones Jr., 1982)
Western harvest mice build spherical nests. These are usually located directly on the ground, beneath the cover of grasses, bushes, weeds, or logs. These nests are about 125 mm in diameter. The inside of the nest is usually lined with softer, finer plant material, whereas the outer portion has coarser plant fibers. Access to this nest is provided by one or more holes in the base of the sphere. Occasionally, (Webster and Jones Jr., 1982)has been known to build nests in shrubs above ground level, or in burrows.
Like many rodents, (Webster and Jones Jr., 1982)seems to be able to get its bearings when it is placed outside of its normal home range. When displaced up to 1000 feet from its normal range, is able to find its way back.
Desity of these mice varies geographically. They have been measured at densities of 11.9 per hectare to only 4 per hectare. One measurement of about 60 mice per hectare was made when the gound vegetation improved and became very dense due to rains. (Webster and Jones Jr., 1982)
Home range size apparently varies with location. In California, home ranges of about 3,525 square meters were reported. (Webster and Jones Jr., 1982)
Communication patterns have not been reported for these mice. It is likely that they communicate with conspecifics with a combination of olfactory/chemical cues, vocalizations, and tactile communication, as these avenues of communication are prevalent in rodents.
The primary diet of this mouse is seeds. However, it eats anything available at the time, including new growth of plants and insects (grasshoppers and moths). These animals sometimes cache food in their nests. (Nowak, 1999; Ruff and Wilson, 1999; Webster and Jones Jr., 1982)drinks water.
Because of their noctural activity, it is likely that these mice have the best opportunity of avoiding predation by nocturnal predators. These mice are most active on very dark nights, which may be a strategy for avoiding predation by animals that use vision to detect prey. (Nowak, 1999)
This species is essential to western ecosystems. It reproduces rapidly, and lives a very short time, even when removed from the threat of predation. This indicates that the species does not live long in the wild. The most likely source of mortality is predation. (eNature.com, 2000; Nowak, 1999; Ruff and Wilson, 1999; Webster and Jones Jr., 1982)
As a prey species, the availability oflikely controls the populations of many predators which rely heavily upon this species in their prey base.
Also, because (Nowak, 1999)caches seeds, it probably helps in their dispersal.
There is no known benefit of this species for humans. However, because they are important in the food web, many of the higher profile animals that people enjoy watching, such as hawks, owls, coyotes, and foxes, rely on them.
There are no reports of these mice actually damaging crops. However, human agriculture has positively affected (