Water Shrew - Sorex palustris
FWP Conservation Tier
A large, semiaquatic, blackish-gray shrew with a long bicolored tail and large hind feet fringed with short stiff hairs. Total length is 14 to 16 cm (5.5 to 6.3 inches) including a 6 to 8 cm (2.4 to 3.1 inch) tail. The dense fur is glossy blackish gray above and paler or silvery beneath. Middle toes of hind feet (18 to 20 mm) are partially webbed. For good descriptions and illustrations see Burt and Grossenheider (1976), Godin (1977), Hall (1981), Beneski and Stinson (1987), Clark (1987), and Merritt (1987). The sexes are similar in size and color. Sexually active males (February to September) have prominent dermal glands on each side between fore and hind legs. They show in S. p. navigator as an 8-mm oval patch of white hair (Conaway 1952). Immatures are similar in color to adults. The skull is large and heavy for a shrew, generally more than 19.5 mm long in S. p. punctulatus. The first two unicuspid teeth are noticeably larger than the next two (Banfield 1974), the third unicuspid is smaller than the fourth (Godin 1977), and the fifth is greatly reduced (Pagels 1986). For comparative illustrations of shrew dentition, see Conaway (1952), Banfield (1974), Churchfield (1990). The teeth of North American shrews show some reddish brown pigmentation. Scats of Water Shrews are quite distinctive, black and granular in structure, being full of remains of invertebrate exoskeletons. They are often deposited in middens on the banks of streams, in surface burrows, at burrow entrances, in the lee of rocks at the stream edge, or even sometimes quite prominently on the tops of stones (Churchfield 1990). Water Shrew hairs are roughly H-shape in cross section, with inner surfaces deeply ridged (see illustration in Churchfield 1990).
Stiff hairs along the sides of the hind feet are found only in the Water Shrew and the Pacific Water Shrew (Sorex bendirii). The latter, a Pacific Northwest species, differs in being slightly larger (8.9 to 9.7 cm, 3.5 to 3.8 inches, body length) and dark brown rather than blackish-gray (Burt and Grossenheider 1976). See Carraway (1995) for a key to western North American soricids based primarily on dentaries.
Summary of Observations Submitted for Montana
Number of Observations:
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Map Help and Descriptions
(Records associated with a range of dates are excluded from time charts)
In streamside habitat in coniferous forests, particularly in or under overhanging banks or crevices; prefer good cover (Conaway 1952). However, also found in seasonal streams and small seeps (Kinsella 1967). Also above timberline (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:
- 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);
- Evaluating structural characteristics and distribution of each ecological system relative to the species’ range and habitat requirements;
- Examining the observation records for each species in the state-wide point database associated with each ecological system;
- 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 email@example.com
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.
- 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.
- Commonly Associated with these Ecological Systems
Forest and Woodland Systems
Open Water / Wetland and Riparian Systems
Shrubland, Steppe and Savanna Systems
- Occasionally Associated with these Ecological Systems
Forest and Woodland Systems
Shrubland, Steppe and Savanna Systems
Aquatic insect larvae, also some vegetable matter, Oligochaetes, other shrews, arachnids, and small fish (Conaway 1952). Captures in small seeps (Kinsella 1967) imply dietary flexibility.
A captive specimen required cold water. Used smell and tactile senses to capture fish. Fur would become soaked within several minutes immersion, and specimen dried itself by working fur with hind feet (Conaway 1952).
Males produce sperm December to August. Pregnant or lactating females found February to August. Several litters/season, around 6 young/litter. Males reproductively mature 2nd year, females 1st year but often do not produce litter until 2nd year.
- Additional ReferencesLegend: View WorldCat Record View Online Publication
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- Beneski, J. T. and D. W. Stinson. 1987. Sorex palustris. American Society of Mammalogists, Lawrence, KS. Mammalian Species No. 296:1-6.
- 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.
- Conaway, C. H. 1952. Life history of the water shrew (SOREX PALUSTRIS NAVIGATOR). Amer. Midl. Nat. 48:219-248.
- Dice, L.R. 1923. Mammal associations and habitats of the Flathead Lake Region, Montana. Ecology 4(3):247-260.
- Foresman, K. R. 2001. The wild mammals of Montana. American Society of Mammologists, Special Publication Number 12. Lawrence, KS. 278 p.
- Hoffmann, R. S. and D. L. Pattie. 1968. A guide to Montana mammals: identification, habitat, distribution, and abundance. University of Montana, Missoula. 133 p.
- Kinsella, J. M. 1967. Unusual habitat of the water shrew in western Montana. J. Mammal. 48(3):475-477.
- OEA Research, Helena, MT., 1982, Beal Mine Wildlife Report. June 17, 1982.
- Pattie, D. L. and N. A. M. Verbeek. 1967. Alpine mammals of the Beartooth Plateau. Northwest Science 41(3): 110-117.
- Reichel, J. D. 1986. Habitat use by alpine mammals in the Pacific Northwest. Arc. Alp. Res. 18(1): 111-119.
- 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.
- 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.
- Zackheim, Karen, 1973?, Exhibit H: Wildlife Study. In Ash Grove Cement Co. files.
- Additional Sources of Information Related to "Mammals"