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Montana Field Guides

Masked Shrew - Sorex cinereus

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Global Rank: G5
State Rank: S5

Agency Status
USFWS:
USFS:
BLM:
FWP Conservation Tier: 3


 

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General Description
A medium-sized shrew (adults usually 9 to 11 cm total length, tail 35 to 45 mm, 3 to 6 g) with a sharply pointed snout, beady eyes, and small ears nearly hidden in the fine soft pelage; dorsal pelage varies from dark brown to gray, depending on the season and location. Five small unicuspidate teeth behind the upper incisors: the fifth is minute, the fourth generally is smaller than the third (the fourth is less commonly equal to, or sometimes larger than the third in subspecies ohioensis) and both of these are smaller than the first and second; tips of teeth are dark chestnut; feet are delicate, with slender weak claws; condylobasal length of skull 14.6 to 16.9 mm; maxillary breadth less than 4.6 mm; posterior border of infraorbital foramen even with, or anterior to, plane of space between M1 and M2 (Godin 1977, Hall 1981, Armstrong 1987).

Diagnostic Characteristics
Generally paler and smaller than S. fumeus (95 to 129 mm total length) (Godin 1977). See Hall (1981) for a key to North American species of Sorex. See Carraway (1995) for a key to western North American soricids based primarily on dentaries.

Species Range
Montana Range

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Western Hemisphere Range

 


Summary of Observations Submitted for Montana
Number of Observations: 455

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

Recency

 

(Records associated with a range of dates are excluded from time charts)



Migration
Non-migratory.

Habitat
Coniferous forest (Junge and Hoffmann 1981). In western Montana, where Sorex vagrans also occurs, S. cinereus is usually restricted to drier coniferous forest habitat (Hoffmann and Pattie 1968).

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 (high, medium, or low) 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 2001, 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 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 associated as using 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 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.  High, medium, and low habitat quality was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species in the 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 assignments of habitat quality.  If you have any questions or comments on species associations with ecological systems, please contact Bryce Maxell at bmaxell@mt.gov or (406) 444-3655.

    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: http://mtnhp.org/requests/default.asp) 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.  2001.  The wild mammals of Montana.  Special Publication No. 12.  Lawrence, KS: The American Society of Mammalogists.  278 p.
    • 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
Invertebrates, salamanders, small mice. In winter, seeds may be main item in diet (van Zyll de Jong 1983).

Ecology
Populations fluctuate year to year. Birds, snakes, and mammalian carnivores are predators (van Zyll de Jong 1983).

Reproductive Characteristics
Probably polyestrous. Spring (April) to autumn, altricial young born in a spherical nest of dry vegetation (van Zyll de Jong 1983).

References
  • Additional ReferencesLegend:   View WorldCat Record   View Online Publication
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    • Brown, L.N. 1967. Ecological distribution of six species of shrews and comparison of sampling methods in the central Rocky Mountains. Journal of Mammalogy 48(4): 617-623.
    • Camp Dresser & McKee, Inc., Wheat Ridge, CO., 1981, Anaconda Stillwater Project 6-month environmental baseline report. CDM Project No. 3139. Vol. I Appendix. Jan. 15, 1981.
    • Carlsen, Tom, and Rick Northrup, 1992, Canyon Ferry Wildlife Management Area Final Draft Management Plan. March 1992.
    • Clark, T. W. 1973. Distribution and reproduction of shrews in Grand Teton National Park, Wyoming. Northwest Sci. 47(2): 128-131.
    • Foresman, K. R. 2001. The wild mammals of Montana. American Society of Mammologists, Special Publication Number 12. Lawrence, KS. 278 p.
    • Forsyth, D. J. 1976. A field study of growth and development of nestling masked shrews (Sorex cinereus). J. Mammal, 57(4): 708-721.
    • Hayward, G. D. and P. H. Hayward. 1995. Relative abundance and habitat associations of small mammals in the Chamberlain Basin, central Idaho. Northwest Sci. 69(2): 114-125.
    • Hoffmann, R. S. and D. L. Pattie. 1968. A guide to Montana mammals: identification, habitat, distribution, and abundance. University of Montana, Missoula. 133 p.
    • Innes, D. G., Bendell, J. F., Naylor, B. J. and B. A. Smith. 1990. High densities of the Masked Shrew, Sorex cinereus, in Jack Pine plantations in northern Ontario. Am. Midl. Nat. 124(2): 330-341.
    • Junge, J. A. and R. S. Hoffmann. 1981. An annotated key to the long-tailed shrews (genus Sorex) of the United States and Canada, with notes on middle American Sorex. Occasional Papers of the Museum of Natural History, the University of Kansas 94: 1-48.
    • MacCracken, J. G., D. W. Uresk, and R. M. Hansen. 1985. Habitat used by shrews in southeastern Montana. Northwest Science 59(1):24-27.
    • Martin, Steve A., ECON, Inc., Helena, MT., 1982, Flathead Project Wildlife Report, 1981-1982. November 30, 1982.
    • Montana Dept. of State Lands. U.S. Office of Surface Mining., 1985, Draft Environmental Impact Statement. Consolidation Coal Company. CX Ranch Mine, Big Horn County, Montana.
    • OEA Research, Helena, MT., 1982, Beal Mine Wildlife Report. June 17, 1982.
    • Powder River Eagle Studies, Gillette, WY., 1992, Big Sky Mine 1991 wildlife monitoring studies. Rev. February 1992.
    • Reid, F. 2006. Peterson Field Guide to Mammals of North America, 4th Edition. Houghton Mifflin Company: Boston and New York, 608 pp.
    • Rust, H. J. 1946. Mammals of northern Idaho. J. Mammal. 27(4): 308-327.
    • Spencer, A. W. and D. Pettus. 1966. Habitat preferences of five sympatric species of long-tailed shrews. Ecology 47: 677-683.
    • Stearns-Roger Inc., 1975, Environmental baseline information of the Mount Vernon Region, Montana. January 31, 1975.
    • Stewart, D. T., T. B. Herman, and T. Teferi. 1989. Littoral feeding in a high-density insular population of SOREX CINEREUS. Can. J. Zool. 67: 2074-2077.
    • Thompson, Richard W., Western Resource Dev. Corp., Boulder, CO., 1996, Wildlife baseline report for the Montana [Montanore] Project, Lincoln and Sanders counties, Montana. In Application for a Hard Rock Operating Permit and Proposed Plan of Operation, Montanore Project, Lincoln and Sanders Counties, Montana. Vol. 5. Stroiazzo, John. Noranda Minerals Corp., Libby, MT. Revised September 1996.
    • 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.
    • Westmoreland Resources, Inc., Hardin, MT., 1981, Upper Sarpy Basin Wildlife Study. In 1981 Wildlife Report. April 1982.
    • Whitaker, J. O., Jr. 2004. Sorex cinereus. American Society of Mammalogists, Lawrence, KS. Mammalian Species No. 743:1-9.
    • Williams, O. 1955. Distribution of mice and shrews in a Colorado montane forest. J. Mammal. 36(2): 221-231.
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Citation for data on this website:
Masked Shrew — Sorex cinereus.  Montana Field Guide.  Montana Natural Heritage Program and Montana Fish, Wildlife and Parks.  Retrieved on December 21, 2014, from http://FieldGuide.mt.gov/speciesDetail.aspx?elcode=AMABA01010
 
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