Search Field Guide
Advanced Search
MT Gov Logo
Montana Field Guide

Montana Field Guides

Western Harvest Mouse - Reithrodontomys megalotis

Image Copyright and Usage Information
Native Species

Global Rank: G5
State Rank: S5
(see State Rank Reason below)


Agency Status
USFWS:
USFS:
BLM:


 

External Links

State Rank Reason (see State Rank above)
Species is apparently secure and not at risk of extirpation or facing significant threats in all or most of its range.
  • Details on Status Ranking and Review
    Western Harvest Mouse (Reithrodontomys megalotis) Conservation Status Review
    Review Date = 05/03/2018
    Range Extent

    ScoreG - 200,000-2,500,000 km squared (about 80,000-1,000,000 square miles)

    Comment228,176 square Kilometers from Natural Heritage Program range maps

    Long-term Trend

    ScoreE - Relatively Stable (±25% change)

    CommentHabitat is likely stable within +/- 25% since European settlement

    Short-term Trend

    ScoreU - Unknown. Short-term trend in population, range, area occupied, and number and condition of occurrences unknown.

    CommentNo data on trends available

    Threats

    ScoreH - Unthreatened. Threats if any, when considered in comparison with natural fluctuation and change, are minimal or very localized, not leading to significant loss or degradation of populations or area even over a few decades’ time. (Severity, scope, and/or immediacy of threat considered Insignificant.)

    CommentNo operational threats in the next 15-20 years identified

    Intrinsic Vulnerability

    ScoreC - Not Intrinsically Vulnerable. Species matures quickly, reproduces frequently, and/or has high fecundity such that populations recover quickly (< 5 years or 2 generations) from decreases in abundance; or species has high dispersal capability such that extirpated populations soon become reestablished through natural recolonization (unaided by humans).

    CommentNot Intrinsically Vulnerable. Species matures quickly, reproduces frequently, and/or has a high fecundity such that populations recover quickly (< 5 years or 2 generations) from decreases in abundance. Species has good dispersal capabilities such that e

    Environmental Specificity

    ScoreD - Broad. Generalist. Broad-scale or diverse (general) habitat(s) or abiotic and/or biotic factors are used or required by the species, with all key requirements common in the generalized range of the species in the area of interest. If the preferred food(s) or breeding/nonbreeding microhabitat(s) become unavailable, the species switches to an alternative with no resulting decline in numbers of individuals or number of breeding attempts.

    CommentFound in a diversity of grass and shrub dominated habitats and agricultural areas

    Raw Conservation Status Score

    Score 3.5 + 0 (geographic distribution) + 0.5 (environmental specificity) + 0 (long-term trend) + 1 (threats) = 5

 
General Description
The relatively small Western Harvest Mouse averages 5 1/2 inches long and less than 1/2 ounce in weight. Its scaly tail comprises more than half of its length. The upper fur and tail color appears grayish brown, with a darker midline and buffy sides. Below, tail and body are white or grayish. Along with the nearly hairless bicolored tail, large ears and a groove running down the front of each incisor help differentiate the Western Harvest Mouse from similar mammals.

Diagnostic Characteristics
See Hoofer et al. (1999) for information on discrimination between R. megalotis and R. montanus using cranial characters.

Species Range
Montana Range Range Descriptions

Native

Western Hemisphere Range

 


Observations in Montana Natural Heritage Program Database
Number of Observations: 250

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density

Recency

 

(Observations spanning multiple months or years are excluded from time charts)



Migration
Non-migratory.

Habitat
Dense grassy areas, sage-grassland.

Ecological Systems Associated with this Species
  • Details on Creation and Suggested Uses and Limitations
    How Associations Were Made
    We associated the use and habitat quality (common or occasional) of each of the 82 ecological systems mapped in Montana for vertebrate animal species that regularly breed, overwinter, or migrate through the state by:
    1. Using personal observations and reviewing literature that summarize the breeding, overwintering, or migratory habitat requirements of each species (Dobkin 1992, Hart et al. 1998, Hutto and Young 1999, Maxell 2000, Foresman 2012, Adams 2003, and Werner et al. 2004);
    2. Evaluating structural characteristics and distribution of each ecological system relative to the species' range and habitat requirements;
    3. Examining the observation records for each species in the state-wide point observation database associated with each ecological system;
    4. Calculating the percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system to get a measure of "observations versus availability of habitat".
    Species that breed in Montana were only evaluated for breeding habitat use, species that only overwinter in Montana were only evaluated for overwintering habitat use, and species that only migrate through Montana were only evaluated for migratory habitat use.  In general, species were listed as associated with an ecological system if structural characteristics of used habitat documented in the literature were present in the ecological system or large numbers of point observations were associated with the ecological system.  However, species were not listed as associated with an ecological system if there was no support in the literature for use of structural characteristics in an ecological system, even if point observations were associated with that system.  Common versus occasional association with an ecological system was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species as represented in scientific literature.  The percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system was also used to guide assignment of common versus occasional association.  If you have any questions or comments on species associations with ecological systems, please contact the Montana Natural Heritage Program's Senior Zoologist.

    Suggested Uses and Limitations
    Species associations with ecological systems should be used to generate potential lists of species that may occupy broader landscapes for the purposes of landscape-level planning.  These potential lists of species should not be used in place of documented occurrences of species (this information can be requested at: mtnhp.org/requests) or systematic surveys for species and evaluations of habitat at a local site level by trained biologists.  Users of this information should be aware that the land cover data used to generate species associations is based on imagery from the late 1990s and early 2000s and was only intended to be used at broader landscape scales.  Land cover mapping accuracy is particularly problematic when the systems occur as small patches or where the land cover types have been altered over the past decade.  Thus, particular caution should be used when using the associations in assessments of smaller areas (e.g., evaluations of public land survey sections).  Finally, although a species may be associated with a particular ecological system within its known geographic range, portions of that ecological system may occur outside of the species' known geographic range.

    Literature Cited
    • Adams, R.A.  2003.  Bats of the Rocky Mountain West; natural history, ecology, and conservation.  Boulder, CO: University Press of Colorado.  289 p.
    • Dobkin, D. S.  1992.  Neotropical migrant land birds in the Northern Rockies and Great Plains. USDA Forest Service, Northern Region. Publication No. R1-93-34.  Missoula, MT.
    • Foresman, K.R.  2012.  Mammals of Montana.  Second edition.  Mountain Press Publishing, Missoula, Montana.  429 pp.
    • Hart, M.M., W.A. Williams, P.C. Thornton, K.P. McLaughlin, C.M. Tobalske, B.A. Maxell, D.P. Hendricks, C.R. Peterson, and R.L. Redmond. 1998.  Montana atlas of terrestrial vertebrates.  Montana Cooperative Wildlife Research Unit, University of Montana, Missoula, MT.  1302 p.
    • Hutto, R.L. and J.S. Young.  1999.  Habitat relationships of landbirds in the Northern Region, USDA Forest Service, Rocky Mountain Research Station RMRS-GTR-32.  72 p.
    • Maxell, B.A.  2000.  Management of Montana's amphibians: a review of factors that may present a risk to population viability and accounts on the identification, distribution, taxonomy, habitat use, natural history, and the status and conservation of individual species.  Report to U.S. Forest Service Region 1.  Missoula, MT: Wildlife Biology Program, University of Montana.  161 p.
    • Werner, J.K., B.A. Maxell, P. Hendricks, and D. Flath.  2004.  Amphibians and reptiles of Montana.  Missoula, MT: Mountain Press Publishing Company. 262 p.

Food Habits
Granivorous, also consumes some herbaceous materials and insects.

Ecology
Tolerant of conspecifics.

Reproductive Characteristics
Average 4.0 young/litter (n=2). In warmer parts of range breeds year round. Probably March to October in MT. Females are sexually mature in 4 months, polyestrous, several litters year.


References
  • Literature Cited AboveLegend:   View Online Publication
    • Hoofer, S.R., J.R. Choate, and N.E. Mandrak. 1999. Mensural discrimination between Reithrodontomys megalotis and R. montanus using cranial characters. Journal of Mammalogy 80:91-101.
  • Additional ReferencesLegend:   View Online Publication
    Do you know of a citation we're missing?
    • Allen, K.L., T. Weaver, and D. Flath. 1994. Small mammals in Northern Rocky Mountain ecosystems. Unpubl. report to Bureau of Land Management and United States Forest Service, August 31, 1994. Montana State Univ., Bozeman. 54 pp.
    • Bachen, D.A. 2014. Cheatgrass invasion of sagebrush steppe: Impacts of vegetation structure on small mammals. M.Sc. Thesis. Bozeman, Montana: Montana State University. 96 p.
    • Bauer, Delane, 2002, 2002 Four Seasons Wildlife Study. Savage Mine Report, Richland County, Montana.
    • Bowdoin NWR. 2000. A survey of the small, terrestrial mammals at Bowdoin NWR: Malta, Montana.
    • Bramblett, R.G., and A.V. Zale. 2002. Montana Prairie Riparian Native Species Report. Montana Cooperative Fishery Research Unit, Montana State University - Bozeman.
    • Clark, B. K. and D. W. Kaufman. 1990. Short-term responses of small mammals to experimental fire in tallgrass prairie. Can. J. Zool. 68:2450-2454.
    • Clark, B. K., et al. 1988. Long-distance movements by Reithrodontomys megalotis [sic] in tallgrass prairie. Am. Midl. Nat. 120:276-281
    • Clark, S.G. and M.R. Stromberg. 1987. Mammals in Wyoming. University of Kansas Museum of Natural History, Public Education Series Number 10. xii + 314 pp.
    • Dames & Moore. 1975. Interim report environmental baseline studies for Crow Indian coal leases: known as Tract II and Tract III, Westmoreland Resources, Sarpy Creek Basin, Big Horn County, Montana. Billings, Mont.
    • Dood, A.R. 1980. Terry Badlands nongame survey and inventory final report. Montana Department of Fish, Wildlife, and Parks and Bureau of Land Management, Helena, MT. 70 pp.
    • ECON, Inc. (Ecological Consulting Service), Helena, MT., 1975, Colstrip 10 x 20 Area wildlife and wildlife habitat annual monitoring report, 1975. Proj. 71-23-A. December 31, 1975.
    • ECON, Inc. (Ecological Consulting Service), Helena, MT., 1979, Annual wildllife report of the Colstrip Area for 1978. Proj. 195-85-A. April 6, 1979.
    • Econ, Inc. 1988. Wildlife monitoring report, 1987 field season, Big Sky Mine. March 1988. In Peabody Mining and Reclamation Plan Big Sky Mine Area B. Vol. 8, cont., Tab 10 - Wildlife Resources. Appendix 10-1, 1987 Annual Wildlife Report.
    • Econ, Inc., Helena, MT., 1978, Peabody Coal Company Big Sky Mine, Rosebud County, MT. Wildlife and wildlife habitat monitoring study. Proj. 190-85-A. December 31, 1978.
    • Fjell, Alan K., 1986, Peabody Coal Company Big Sky Mine, Rosebud County, MT. Wildlife monitoring report: 1985 field season. March 1986.
    • Fjell, Alan K., and Brian R. Mahan, compilers., 1984, Peabody Coal Company Big Sky Mine, Rosebud County, MT. Wildlife monitoring report: 1983 field season. February 1984.
    • Fjell, Alan K., and Brian R. Mahan., 1985, Peabody Coal Company Big Sky Mine, Rosebud County, MT. Wildlife monitoring report: 1984 field season. February 1985.
    • Fjell, Alan K., and Brian R. Mahan., 1987, Big Sky Mine, Rosebud County, MT. Wildlife monitoring report: 1986 field season. April 1987.
    • Foresman, K.R. 2001. The wild mammals of Montana. American Society of Mammalogists, Special Publication Number 12. Lawrence, KS. 278 pp.
    • Foresman, K.R. 2012. Mammals of Montana. Second edition. Mountain Press Publishing, Missoula, Montana. 429 pp.
    • Geppert, T. J. 1984. Small mammals of the Shield Trap, East Pryor Mountain, Montana. M.S. thesis. University of Iowa, Iowa City. 45 pp.
    • Gniadek, S. 1983. Southwest Glendive Wildlife Baseline Inventory. Miles City, Mont: Bureau of Land Management, Miles City District Office. 56 pp with appendices.
    • Hanauska-Brown, L., B.A. Maxell, A. Petersen, and S. Story. 2014. Diversity Monitoring in Montana 2008-2010 Final Report. Montana Fish, Wildlife & Parks. Helena, MT. 78 pp.
    • Hendricks, P., S. Lenard, D.M. Stagliano, and B.A. Maxell. 2013. Baseline nongame wildlife surveys on the Fort Peck Indian Reservation. Report to the Assiniboine and Sioux Tribes of the Fort Peck Indian Reservation. Montana Natural Heritage Program, Helena, MT. 83 p.
    • Heske, E. J., R. S. Ostfeld and W. Z. Lidicker, Jr. 1984. Competitive interactions between Microtus californicus and Reithrodontomys megalotis during two peaks of Microtus abundance. J. Mammal. 65:271-280.
    • Hoffmann, R.S. and D.L. Pattie. 1968. A guide to Montana mammals: identification, habitat, distribution, and abundance. Missoula, MT: University of Montana. 133 p.
    • Hoffmann, R.S., P.L. Wright, and F.E. Newby. 1969. The distribution of some mammals in Montana. I. Mammals other than bats. Journal of Mammalogy 50(3): 579-604.
    • Jones, J.K., D.M. Armstrong, R.S. Hoffmann and C. Jones. 1983. Mammals of the northern Great Plains. University of Nebraska Press, Lincoln. 379 pp.
    • Joslin, Gayle, and Heidi B. Youmans. 1999. Effects of recreation on Rocky Mountain wildlife: a review for Montana. [Montana]: Montana Chapter of the Wildlife Society.
    • Kaufman, G.A., D.W. Kaufman and E.J. Finck. 1988. Influence of fire and topography on habitat selection by Peromyscus maniculatus and Reithrodontomys megalotis in ungrazed tallgrass prairie. Journal of Mammalogy 69:342-352.
    • Kritzman, E.B. 1977. Little mammals of the Pacific Northwest. Pacific Search Press, Seattle, WA.
    • LaVelle, Darlene. 1988. 1988 Nongame surveys in Region 5 and Region 7.' MTFWP. 40pp.
    • Martin, P.R., K. Dubois and H.B. Youmans. 1981. Terrestrial wildlife inventory in selected coal areas, Powder River resources area final report. Montana Department of Fish, Wildlife and Parks and Bureau of Land Management, Helena, MT. No. YA-553-CTO- 24. 288 p.
    • Matthews, W.L. 1980a. Wibaux-Beach comparison study: Sydney, Glendive and Plevna Study Areas. Bureau of Land Management, Miles City, MT. 50 p.
    • Matthews, W.L. 1981. Broadus-Pumpkin Creek baseline inventory - wildlife. Bureau of Land Management, Miles City, MT. 83 p.
    • Montana Dept. of State Lands, 1976, Draft environmental impact statement for proposed open cut mining contract for Amercan Colloid Company. November 12, 1976.
    • Pefaur, J. E., and R. S. Hoffmann. 1975. Studies of small mammal populations at three sites on the Northern Great Plains. Occasional Papers of the Museum of Natural History, University of Kansas, Lawrence. No. 37:1-27.
    • Pefaur, J.E. and R.S. Hoffmann. 1971. Merriam's shrew and hispid pocket mouse in Montana. American Midland Naturalist 86(1):247-248.
    • Powder River Eagle Studies, Inc., Gillette, WY., 1994?, Big Sky Mine 1993 wildlife studies. Date???
    • Reid, F. 2006. Peterson Field Guide to Mammals of North America, 4th Edition. Houghton Mifflin Company: Boston and New York, 608 pp.
    • Schladweiler, Philip, and John P. Weigand., 1983, Relationships of endrin and other chlorinated hydrocarbon compounds to wildlife in Montana, 1981-1982. September 1983.
    • Scow, K.L. 1981. Ecological distribution of small mammals at Sarpy Creek, Montana, with special consideration of the Deer Mouse, Peromyscus maniculatus. M.Sc. Thesis. Bozeman, Montana: Montana State University. 73 p.
    • Thompson, L.S. 1981. Circle West wildlife monitoring study: Third annual report. Technical report No. 8. Montana Department of Natural Resources and Conservation. Helena, Montana.
    • Waage, B.C. 1984. Western Energy Company Rosebud Mine, Rosebud County, Montana: Annual Wildlife Monitoring Report, 1983 Field Season. June 1984.
    • Waage, B.C. 1986. Western Energy Company Rosebud Mine, Rosebud County, Montana: Annual Wildlife Monitoring Report, 1985 Field Season. December 1985.
    • Waage, Bruce C., 1993, Western Energy Company Rosebud Mine, Colstrip, Montana: Annual Wildlife Monitoring Report; 1992 Field Season. December 1993.
    • Waage, Bruce C., 1995, Western Energy Company Rosebud Mine, Colstrip, Montana:1994 Annual Wildlife Monitoring Report; December 1, 1993 - November 30, 1994. February 27, 1995.
    • Waage, Bruce C., 1996, Western Energy Company Rosebud Mine, Colstrip, Montana: 1995 Annual Wildlife Monitoring Report; December 1, 1994 - November 30, 1995. February 28, 1996.
    • Waage, Bruce C., 1999, Western Energy Company Rosebud Mine, Colstrip, Montana: 1998 Annual Wildlife Monitoring Report; December 1, 1997 - November 30, 1998 Survey Period. February 24, 1999.
    • Webster, W.D. and J.K. Jones. 1982. Reithrodontomys megalotis. Mamm. Species No. 167. 5 pp.
    • Western Energy Co., Colstrip, MT. Unpub., 1983, Western Energy Company's Application for Amendment to Surface Mining Permit NO. 8003, Area B: sections 7, 8, 17,18 T1N R41E, sections 12, 13 T1N R40E, Mining Expansion. March 1983.
    • Western Energy Co., Colstrip, MT., 1980, Western Energy Company Rosebud Mine, Colstrip, Montana: Annual Wildlife Report, 1980.
    • Western Energy Co., Colstrip, MT., 1981, Western Energy Company Rosebud Mine, Colstrip, Montana: Annual Wildlife Report, 1981.
    • Western Energy Co., Colstrip, MT., 1981, Western Energy Company's Application for a Surface Mining Permit: Area C - Block 1. Vol. 1. May 1981.
    • Western Technology and Engineering, Inc. (WESTECH)., 1996, Wildlife Monitoring Absaloka Mine Area Annual Report, 1995. Montana SMP 85005. OSMP Montana 0007D. Febr. 23, 1996.
    • Western Technology and Engineering, Inc. (WESTECH)., 1997, Wildlife Monitoring Absaloka Mine Area Annual Report, 1996. Montana SMP 85005. OSMP Montana 0007D. Mar. 1997.
    • Western Technology and Engineering, Inc. (WESTECH)., 1999, Wildlife Monitoring Absaloka Mine Area Annual Report, 1998. SMP 85005. OSMP Montana 0007E. April 1999.
    • Westmoreland Resources, Inc., Hardin, MT., 1981, Upper Sarpy Basin Wildlife Study. In 1981 Wildlife Report. April 1982.
  • Web Search Engines for Articles on "Western Harvest Mouse"
  • Additional Sources of Information Related to "Mammals"
Login Logout

Take us with you! PDF icon

Look for this PDF icon as you search and browse.  Click it to build a custom PDF with species shown on that page or for all the species within that taxonomic level.  To create your own list of species, use the PDF Creator tool at the bottom of the Advanced Search page.

Here's some links if you want to download a whole group.

Mammals
Birds
Reptiles
Amphibians
Fish
Invertebrates
Butterflies / Moths
Dragonflies / Damselflies
Ferns and allies
Conifers
Flowering Plants (Dicots)
Flowering Plants (Monocots)
Bryophytes
Lichens
Ecological Systems
Noxious Weeds
Citation for data on this website:
Western Harvest Mouse — Reithrodontomys megalotis.  Montana Field Guide.  .  Retrieved on , from