Reithrodontomys megalotis


Taxonomy [top]

Kingdom Phylum Class Order Family

Scientific Name: Reithrodontomys megalotis
Species Authority: (Baird, 1857)
Common Name(s):
English Southern Marsh Harvest Mouse, Western Harvest Mouse
Taxonomic Notes: Differences in chromosome numbers among populations suggest that two or more sibling species may be subsumed under P. megalotis.

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2008
Date Assessed: 2008-06-30
Assessor(s): Linzey, A.V. & Matson, J.
Reviewer(s): McKnight, M. (Global Mammal Assessment Team) & Amori, G. (Small Nonvolant Mammal Red List Authority)
This species is listed as Least Concern in view of its wide distribution, presumed large population, tolerance of a broad range of habitats, occurrence in a number of protected areas, and because it does not appear to be under threat and is unlikely to be declining at nearly the rate required to qualify for listing in a threatened category.

Geographic Range [top]

Range Description: Known from portions of southwestern Canada, south through the western and mid-western United States, to southern Mexico (Musser and Carleton 2005). Found from below sea level in Death Valley to 4,000 m in central Mexico. (Webster and Jones 1982). There is evidence that the range within the U.S. is expanding to the east as a result of increased habitat alteration for agricultural use (Ford 1977)
Canada (Alberta, British Columbia); Mexico; United States (Arizona, Arkansas, California, Colorado, Idaho, Indiana, Iowa, Kansas, Minnesota, Missouri, Montana, Nebraska, Nevada, New Mexico, North Dakota, Oklahoma, Oregon, South Dakota, Texas, Utah, Washington, Wisconsin, Wyoming)
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: The western harvest mouse is a widespread and abundant species. Densities may reach up to 60 individuals/ha in late summer (Wilson and Ruff 1999).
Population Trend: Stable

Habitat and Ecology [top]

Habitat and Ecology: This species has wide habitat tolerances. It prefers open, mesic habitats dominated by herbaceous vegetation including meadows, pastures and fallow agricultural fields. This species may also inhabit deserts, shrublands, marshes and cleared areas of pine-oak forests.

R. megalotis is a nocturnal, non-hibernating species. Nests are built of shredded plant material and are typically found on the ground under dense vegetation but may also be found in burrows or in vegetation above the ground (Wilson and Ruff 1999). The diet is opportunistic and is comprised mainly of seeds, herbaceous material and insects. The reproductive potential of a female Western harvest mouse is quite high, with females known to have 14 litters totaling 58 pups within 12 months (Bancroft 1967).
Systems: Terrestrial

Threats [top]

Major Threat(s): No major threats to this species are known.

Conservation Actions [top]

Conservation Actions: There are no known conservation measures specific to this species. Occurs in several protected areas within its range.

Bibliography [top]

Bancroft, W. L. 1967. Record fecundity for Reithrodontomys megalotis. Journal of Mammalogy 48: 306-308.

Ford, S. D. 1977. Range, distribution and habitat of the western harvest mouse, Reithrodontomys megalotis, in Indiana. Amererican Midland Naturalist 98: 422-432.

Musser, G. G. and Carleton, M. D. 1993. Family Muridae. In: D. E. Wilson and D. A. Reeder (eds), Mammal species of the world: A taxonomic and geographic reference, pp. 501-736. Smithsonian Institution Press, Washington, DC, USA.

Webster, W. D. and Jones, J. K. 1982. Reithrodontomys megalotis. Mammalian Species 167: 1-5.

Wilson, D. E. and Ruff, S. 1999. The Smithsonian Book of North American Mammals. Smithsonian Institution Press, Washington, DC, USA.

Citation: Linzey, A.V. & Matson, J. 2008. Reithrodontomys megalotis. The IUCN Red List of Threatened Species. Version 2014.3. <>. Downloaded on 01 April 2015.
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