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Montana Field Guides

Preble's Shrew - Sorex preblei

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Species of Concern

Global Rank: G4
State Rank: S3

Agency Status
USFWS:
USFS:
BLM:
FWP Conservation Tier: 2


 

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General Description
Like other members of the genus Sorex, the snout is long and pointed, and the eyes are small. The dorsal pelage is dark brown to dark gray, and the ventral pelage is silvery-gray. The tail is bicolored, olive-brown above and hazel-brown below. The skull has 32 teeth (dental formula: I 3/1, C 1/1, P 3/1, M 3/3); the 5 upper teeth with single cusps that are present posterior to the first incisor are termed the unicuspids (U), and include 2 incisors, 1 canine, and 2 premolars. The tine on the medial edge of the first incisor is long, acutely pointed, and set within the pigmented area; U3 is as large or larger than U4. Ranges of external measurements (in millimeters) are: total length 77 to 95, tail length 28 to 38, hind foot length 7 to 11, ear length 8 to 11, weight 2.1 to 4.1 grams (Cornely et al. 1992, Verts and Carraway 1998). Published cranial measurements (in millimeters) are: condylobasal length 13.8 to 15.1, palatal length 5.4 to 5.8, cranial breadth 7.0 to 7.2, interorbital breadth 2.9 to 3.1, maxillary breadth 3.8 to 4.2, dentary length 5.6 to 6.7, length of mandibular tooth row (C1-M3) 3.8 to 4.2.

Some Montana specimens (n = 14) exceed some reported values: condylobasal length 13.5 to 14.6, palatal length 5.4 to 6.2, cranial breadth 7.0 to 7.5, interorbital breadth 2.4 to 2.6, maxillary breadth 4.0 to 4.2, dentary length 5.9 to 6.3, length of mandibular tooth row (C1-M3) 4.0 to 4.2 (Hoffmann et al. 1969, Hendricks and Roedel 2002).

Diagnostic Characteristics
Preble's Shrew is small, even for a shrew. Other than its small body size, Preble's Shrew is diagnosed by cranial characteristics. A combination of a medial tine on I1 that is present within the zone of pigmentation, U3 as large or larger than U4, condylobasal length usually less than 15.1 millimeters, palatal length less than 5.8 millimeters, length of dentary less than 6.5 millimeters, length of mandibular tooth row (C1-M3) usually less than 4.1 millimeters, and height of coronoid process less than 3.3 millimeters (Junge and Hoffmann 1981, Carraway 1995).

Species Range
Montana Range

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Western Hemisphere Range

 


Summary of Observations Submitted for Montana
Number of Observations: 54

(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
No information is available on movements in Montana, but based upon information from other locations, the species is considered non-migratory; apparently only local movements are made.

Habitat
Most Preble's Shrews in Montana have been captured in sagebrush-grassland habitats (Hoffmann et al. 1969, Foresman 2012, Hendricks and Roedel 2002), sometimes in openings surrounded by subalpine coniferous forest. They have been taken in Beaverhead County in stabilized sandhills habitat of about 40 to 60% vegetation cover, dominated by grasses (Stipa comata, Festuca idahoensis, Agropyron dasystachyum) and shrubs (Artemisia tridentata, A. tripartita, Chrysothamnus nauseosus, C. viscidiflorus, and Tetradymia canescens), with isolated dense patches of Opuntia fragilis present (Hendricks and Roedel 2002). Preble's Shrew was also present at two other grazed sites (in Beaverhead and Powell counties) dominated by medium-stature (0.5 to 1.5 meters tall) sagebrush; at both sites, sagebrush cover was about 25% (Paul Hendricks, unpublished data).

Throughout its range, the Preble's Shrew occupies a variety of habitats, including arid and semiarid shrub-grass associations, openings in montane coniferous forests dominated by sagebrush, willow-fringed creeks and marshes, bunchgrass associations, sagebrush-aspen associations, sagebrush-grassland, oak chaparral, open ponderosa pine-Gambel oak stands, and alkaline shrubland (Williams 1984, Ports and George 1990, Cornely et al. 1992, Long and Hoffmann 1992, Kirkland and Findley 1996, Verts and Carraway 1998).

The bulk of Preble's Shrews captured have come from arid habitats, often in the immediate or nearby presence of sagebrush. In southwestern Wyoming, individuals were captured in sagebrush-steppe: islands of Artemisia tridentata, Purshia tridentata, and Amelanchier utahensis more than 30 centimeters tall surrounded by large expanses of Artemisia less than 30 centimeters tall (Kirkland et al. 1997). In southern British Columbia, Preble's Shrews were captured in lightly to moderately grazed grassland patches surrounded by scattered stands of Douglas-fir (Pseudotsuga menziesii) or ponderosa pine. Big sagebrush, common snowberry (Symphoricarpos albus), or antelope bitterbush (Purshia tridentata) about 1 to 2 meters in height formed dense shrub cover of 30 to 80% (Nagorsen et al. 2001); cheatgrass (Bromus tectorum) was sometimes dominant, and the nearest standing water to trap sites was 350 to 2300 meters distant.

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
The diet of Preble's Shrew has not been described or the subject of study, but it probably resembles other cinereus-group shrews, feeding on insects and other small invertebrates (worms, molluscs, centipedes, etc.). Its relatively low bite force suggests that it feeds on soft-bodied prey (Cornely et al. 1992, Verts and Carraway 1998). The diet in Montana has not been reported or studied.

Ecology
Little is known about this shrew, but it is probably active all year. It has been captured in spring and late summer in southwestern Wyoming (Kirkland et al. 1997), in summer and during fall to spring in British Columbia (Nagorsen et al. 2001), summer and fall in Nevada (Ports and George 1990), and mid-winter in Utah (Tomasi and Hoffmann 1984). Collection records from Montana range from mid-February to early November.

Other small mammal associates of Preble's Shrew across its range include Sorex cinereus, S. haydeni, S. merriami, S. monticolus, S. nanus, and S. vagrans (Ports and George 1990, Cornely et al. 1992, Kirkland and Findley 1996, Kirkland et al. 1997, Nagorsen et al. 2001). Preble's Shrew has been collected in Montana in close association with Sorex cinereus, and S. monticolus (Hendricks and Roedel 2002).

Vital statistics, measures of population trends, and estimates of population density are not available; at many of the locations where several species of shrews have been captured in association with Preble's Shrew, it is always one of the less abundant species (Ports and George 1990, Kirkland et al. 1997, Nagorsen et al. 2001, Hendricks and Roedel 2002). Predators of Preble's Shrew have not been reported.

Reproductive Characteristics
The reproductive biology in Montana has not been studied, and in general, the reproductive biology of Preble's Shrew is largely unknown (Cornely et al. 1992). In a sample of 26 specimens from southeastern Oregon collected in June and July, five adult females contained developing embryos: two with 3 embryos, two with 5, and one with 6; mean = 4.4 embryos (Carraway and Verts 1999); all had elongated nipples and extensive mammary tissue suggesting they had produced at least one litter earlier. Four juvenile females exhibited no evidence of reproductive activity. For 16 males, testis size in 15 individuals was either less than 2.0 cubic millimeters (nonreproductive, captured in the year of birth) or more than 16.0 cubic millimeters (reproductive, from older cohorts); one male with intermediate testis size had little wear on I1, indicating it may have just reached sexual maturity. These data suggest that at least two litters were produced before the June and July pregnancies.

Management
No management measures have been enacted for Preble's Shrew in Montana. However, alteration or removal of sagebrush through fire, herbicides, or mechanical methods, may impact local populations (Hendricks and Roedel 2001). Measures taken to protect a diversity of size and cover classes of sagebrush will likely contribute to the conservation of Preble's Shrew. Surveys for Preble's Shrews can provide the basis for development of conservation protocols by determining its full distribution in Montana, the array of habitats in which it occurs, its relative abundance in different habitats, and, if properly designed, an idea of how different habitat disturbances affect this rare shrew.

References
  • Literature Cited AboveLegend:   View WorldCat Record   View Online Publication
    • Carraway, L. N. 1995. A key to recent Soricidae of the western United States and Canada based primarily on dentaries. Occasional Papers of the Natural History Museum, University of Kansas (175):1-49.
    • Carraway, L. N. and B. J. Verts. 1999. Records of reproduction in Sorex preblei. Northwestern Naturalist 80:115-116.
    • Cornely, J. E., L. N. Carraway, and B. J. Verts. 1992. Sorex preblei. Mammalian Species 416: 1-3.
    • Foresman, K. R. 2012. Mammals of Montana. Second edition. Mountain Press Publishing, Missoula, Montana. 429 p.
    • Hendricks, P. and M. Roedel. 2001. A faunal survey of the Centennial Valley Sandhills, Beaverhead County, Montana. Report to the U.S. Bureau of Land Management and U.S. Fish and Wildlife Service. Montana Natural Heritage Program, Helena, MT. 44 p.
    • Hendricks, P. and M. Roedel. 2002. Preble's shrew and Great Basin pocket mouse from the Centennial Valley Sandhills of Montana. Northwestern Naturalist 83:31-34.
    • Hoffmann, R.S., P.L. Wright, and F.E. Newby. 1969. Distribution of some mammals in Montana. I. Mammals other than bats. Journal of Mammalogy 50(3): 579-604.
    • 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.
    • Kirkland, G. L., Jr. and J. S. Findley. 1996. First Holocene record for Preble's shrew (Sorex preblei) in New Mexico. Southwestern Naturalist 41:320-322.
    • Kirkland, G. L., Jr., R. R. Parmenter, and R. E. Skoog. 1997. A five-species assemblage of shrews from the sagebrush-steppe of Wyoming. Journal of Mammalogy 78:83-89.
    • Long, C. A. and R. S. Hoffmann. 1992. Sorex preblei from the Black Canyon, first record from Colorado. Southwestern Naturalist 37: 318-319.
    • Nagorsen, D. W., G. G. E. Scudder, D. J. Huggard, H. Stewart, and N. Panter. 2001. Merriam's shrew, Sorex merriami, and Preble's shrew, Sorex preblei: two new mammals for Canada. Canadian Field-Naturalist 115:1-8.
    • Ports, M. A. and S. B. George. 1990. Sorex preblei in the northern Great Basin. Great Basin Naturalist 50: 93-95.
    • Tomasi, T. E. and R. S. Hoffmann. 1984. Sorex preblei in Utah and Wyoming. Journal of Mammalogy 65: 708.
    • Verts, B. J. and L. N. Carraway. 1998. Land mammals of Oregon. University of California Press, Berkeley. xvi + 668 p.
    • Williams, D. F. 1984. Habitat associations of some rare shrews (Sorex) from California. Journal of Mammalogy 65(2):325-328.
  • Additional ReferencesLegend:   View WorldCat Record   View Online Publication
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    • 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. 54pp.
    • Elliott, Joe C. and Hydrometrics, Inc., Helena, MT., 1994, Supplement to wildlife baseline investigation life-of-mine expansion plan: Regal Mine, Barretts Minerals, Inc., Madison County, Montana. August 2000. In Life-of Mine Expansion Plan: Barretts Minerals, Inc., Regal Mine, Madison County, Montana. Vol. 2. App. C: Baseline Wildlife Reconnaissance. December 1999.
    • Emslie, S. D. 2002. Fossil shrews (Insectivora: Soricidae) from the Late Pleistocene of Colorado. Southwestern Naturalist 47:62-69.
    • Flath, D. L. 1984. Vertebrate species of special interest or concern. Mammals, birds, reptiles, amphibians, fishes. Spec. Publ. Montana Department of Fish, Wildlife, and Parks, Helena. 76 pp.
    • Flath, Dennis L., 1979, Nongame species of special interest or concern: Mammals, birds, reptiles, amphibians, fishes. January 1979.
    • Foresman, K. R. 2001. The wild mammals of Montana. American Society of Mammologists, Special Publication Number 12. Lawrence, KS. 278 p.
    • George, S. B. 1988. Systematics, historical biogeography, and evolution of the genus SOREX. J. Mammalogy 69:443-461.
    • Harris, A. H. and L. N. Carraway. 1993. SOREX PREBLEI from the late pleistocene of New Mexico. The Southwestern Naturalist 38:56-58.
    • Hoffmann, R. S. and D. L. Pattie. 1968. A guide to Montana mammals: identification, habitat, distribution, and abundance. University of Montana, Missoula. 133 p.
    • Hoffmann, R. S. and R. D. Fisher. 1978. Additional distributional records of Preble's shrew (SOREX PREBLEI). J. Mammal. 59: 883-884.
    • Reid, F. 2006. Peterson Field Guide to Mammals of North America, 4th Edition. Houghton Mifflin Company: Boston and New York, 608 pp.
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Citation for data on this website:
Preble's Shrew — Sorex preblei.  Montana Field Guide.  Montana Natural Heritage Program and Montana Fish, Wildlife and Parks.  Retrieved on December 18, 2014, from http://FieldGuide.mt.gov/speciesDetail.aspx?elcode=AMABA01030
 
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