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Montana Field Guide

Montana Field Guides

Idaho Pocket Gopher - Thomomys idahoensis

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Potential Species of Concern
Native Species

Global Rank: G4
State Rank: S2S4

Agency Status

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General Description
The Idaho pocket gopher is a small rodent measuring approximately 19 cm from tip of nose to end of tail, and weighing close to 95 g. Slightly smaller in dimensions and lighter in color than the northern pocket gopher, it shares most of the same characteristics: small ears and small black eyes, short fur, a short, nearly hairless tail (just under 4.4 cm in length for the Idaho pocket gopher), well-developed jaw, neck, forearm, and shoulder muscles, long curved claws on its forepaws, exposed yellowish incisors, and the external, furlined cheek pouches, with openings on each side of the mouth. Its fur is yellowish brown on top, sprinkled with dark brown- and grayish brown-tipped hairs; underneath, it will be yellowish or yellowish brown, with whitish feet. (Foresman 2012)

Diagnostic Characteristics
Difficult to distinguish from Montana's other pocket gopher, the northern pocket gopher (Thomomys talpoides), which tends to have a darker reddish brown color, black patches around the ears, and a longer tail, and is much more widely distributed in Montana. Detailed analysis of skull characteristics and chromosome number may be necessary for positive identification. (Foresman 2012)

Species Range
Montana Range Range Descriptions


Western Hemisphere Range


Observations in Montana Natural Heritage Program Database
Number of Observations: 15

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



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


Assumed to occupy a variety of habitats, and to prefer deep, loose soil, as does T. talpoides (Foresman 2012). Some references (see for example Beauvais and Dark-Smiley 2005) suggest they may differ from T. talpoides in a preference for shallower, stonier soils at relatively higher elevations.

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: 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
Assumed to forage on the roots, bulbs, tubers, and stems of a wide variety of plants, as does T. talpoides. Food is carried in cheek pouches to underground storage chambers.

T. idahoensis has only been recognized as a species since 1972, and little specific ecological information is available. Probably similar to T. talpoides in many aspects.

Reproductive Characteristics
For T. talpoides , breeding begins in mid to late April, peaking in May; the gestation period is 18-20 days, and one litter averaging 4-5 young is produced per year. T. idahoensis is assumed to be similar. (Foresman 2012)

Basic natural history information is lacking for the Idaho pocket gopher, and field surveys are merited.

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Citation for data on this website:
Idaho Pocket Gopher — Thomomys idahoensis.  Montana Field Guide.  .  Retrieved on , from