Search Field Guide
Advanced Search
MT Gov Logo
Montana Field Guide

Montana Field Guides

Northern River Otter - Lontra canadensis
Other Names:  North American River Otter

Native Species

Global Rank: G5
State Rank: S4

Agency Status


External Links

Listen to an Audio Sample
Copyright Jeff Rice, all rights reserved. Audio file courtesy of the Acoustic Atlas at Montana State University (
General Description
The adult Northern River Otter in Montana weighs around 20 pounds and measures close to 47 inches long. Its thick, powerful tail makes up nearly 20 inches of that length. Small eyes and ears, a broad, flattened head, long cylindrical form, and four webbed feet suit it for its semiaquatic life. In addition, its fur, dark brown on top, silvery or paler brown on the throat, chest, and underside, has special qualities. The long guard hairs remain pliable in very cold weather (Ulrich 1986), and the dense underfur traps air to insulate it in water. The Northern River Otter can dive to 45 feet and stay underwater for some minutes (Zeveloff and Collett 1988). It is more nocturnal in summer and its eyes reflect a faint amber glow at night. Its short, muscular legs move surprisingly well on land, and is usually seen traveling in pairs (Foresman 2012). It has 36 teeth.

Species Range
Montana Range Range Descriptions


Western Hemisphere Range


Observations in Montana Natural Heritage Program Database
Number of Observations: 1873

(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)

This species is non-migratory.

High flow volume water, densely vegetated and undercut banks preferable, non-turbid water and presence of sloughs and side channels to serve as brood rearing habitat are also important in winter. Open-water stream channels used (Zackheim 1982).

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
Mainly fish. Order of importance varies: sunfish, suckers, sculpin, trout, invertebrates, and frogs. Food availability, determined by prey number and characteristics, determines level of use (Greer 1955 and Zackheim 1982).

Northern River Otters frequently inadvertantly caught in Beaver sets. Perhaps higher human-caused mortality than reported. Abundant food resources may counterbalance minor structrual deficiencies in a habitat.

Reproductive Characteristics
Probably breed every 2 to 3 years. Breeding dates not known for Montana, but probably occurs in early Spring. The young are born fur-covered, but blind (Burt and Grossenheider 1964), they are weaned in approximately 91 days (Toweill and Tabor 1982), and they are ready to fend for themselves at eight months of age (Zeveloff and Collett 1988).

  • Literature Cited AboveLegend:   View Online Publication
    • Burt, W.H. and R.P. Grossenheider. 1964. A field guide to the mammals. Houghton Mifflin Co.
    • Foresman, K.R. 2012. Mammals of Montana. Second edition. Mountain Press Publishing, Missoula, Montana. 429 pp.
    • Greer, K.R. 1955. Yearly food habits of the River Otter in the Thompson Lakes region, northwestern Montana, as indicated by scat analysis. Am. Midl. Nat. 54(2):299-313.
    • Toweill, D.E. And J.E. Tabor. 1982. River Otter Lutra canadensis. Pages 688-703 in J. A. Chapman and G. A. Feldhamer, Editors. Wild Mammals of North America: Biology, Management, and Economics. Johns Hopkins Univ. Press, Baltimore.
    • Ulrich, T.J. 1986, Mammals of the northern Rockies
    • Zackheim, H.S. 1982. Ecology and population status of the river otter in southwestern Montana. M.S. thesis. University of Montana, Missoula. 100 pp.
    • Zeveloff, S.I. and F.R. Collett. 1988. Mammals of the Intermountain west. University of Utah Press, Salt Lake City, Utah.
  • Additional ReferencesLegend:   View Online Publication
    Do you know of a citation we're missing?
    • Allen, T.D.H. 2011. Wildlife guards for deer and Black Bear. M.Sc. Thesis. Bozeman, Montana: Montana State University. 71 p.
    • Berg, W. E. 1982. Reintroduction of fisher, pine marten, and river otter. Pages 159-173 in G. C. Sanderson, editor. Midwest furbearer management. Proc. Symp. 43rd Midwest Fishand Widlife Conference, Wichita, Kansas.
    • Cross, James, and Richard P. Weckwerth, 1977, Upland Game Bird (and Fur Survey) Inventory. Wildlife Investigations, Region One. W-130-R-8, Job No. II-1, July 1, 1976 - June 30, 1977.
    • Cross, James, and Richard P. Weckwerth, 1983, Upland Game Bird (and Fur Survey) Inventory. Wildlife Investigations, Region One. W-130-R-14, Job No. II-1, July 1, 1982 - June 30, 1983.
    • Deems, E.F., Jr. and D. Pursley (eds). 1978. North American furbearers: their management, research and harvest status in 1976. Int. Assoc. Fish and Wildlife Agencies and University of Maryland. 171 p.
    • Dronkert-Egnew, A. 1990. River otter population status, distribution, and habitat use in northwestern Montana. M.S. thesis, University of Montana, Missoula.
    • Dronkert-Egnew, A. E. 1991. River otter population status and habitat use in northwestern Montana. Thesis. Missoula, Montana: University of Montana. 112 p.
    • Dubuc, L. J., W. B. Krohn and R. B. Owen, Jr. 1990. Predicting occurrence of river otters by habitat on Mount Desert Island, Maine. J. Wildl. Manage. 54: 594-599.
    • Foresman, K.R. 2001. The wild mammals of Montana. American Society of Mammalogists, Special Publication Number 12. Lawrence, KS. 278 pp.
    • Greer, K.R. 1953. Yearly food habits of the river otter in the Thompson Lakes region, northwestern Montana, as indicated by scat analysis. M.Sc. Thesis, Bozeman, MT: Montana State University. 30 p.
    • Greer, K.R. 1955a. The otter's diet - good or bad? Montana Wildlife 5(3): 14-17. Montana Fish and Game Department, Helena, MT.
    • Hatier, K.G. 1995. Effects of helping behaviors on Coyote packs in Yellowstone National Park, Wyoming. M Sc. Thesis. Bozeman, MT: Montana State University. 78 p.
    • 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.
    • 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.
    • Koel, T.M., L.M. Tronstad, J.L. Arnold, K.A. Gunter, D.W. Smith, J.M. Syslo, and P.J. White. 2019. Predatory fish invasion induces within and across ecosystem effects in Yellowstone National Park. Science Advances 5:eaav1139.
    • Lariviere, S. and L. R. Walton. 1998. Lontra canadensis. American Society of Mammalogists, Lawrence, KS. Mammalian Species No. 587:1-8.
    • Liers, E.E. 1951. Notes on the river otter (Lutra canadensis). J. Mammal. 32:1-9.
    • Matthews, W.L. and J.E. Swenson. 1982. The mammals of east-central Montana. Proc. Mont. Acad. Sci. 39: 1-13.
    • Melquist, W. E. and A. E. Dronkert. 1987. River otter. Pages 626-641 in M. Novak, J. A. Baker, M. E. Obbard, and B. Malloch, eds. Wild Furbearer Management and Conservation in North America. Ontario Trappers Assn. and Ontario Ministry Nat. Res., Toronto, Ontario.
    • Melquist, W. E. and M. G. Hornocker. 1983. Ecology of river otters in central Idaho. Wildl. Monogr. 83:1-60.
    • Newby, F. E. 1956. A study of the otter's food habits along a segment of the Gallatin River. Montana Fish and Game Dept. P-R Job CompI. Rep., Proj. W-49-R-6, Job II-K.
    • Northrop, Devine & Tarbell, Inc. 1994. Cabinet Gorge and Noxon Rapids hydroelectric developments: 1993 wildlife study. Unpublished report to the Washington Water Power Company, Spokane. Vancouver, Washington and Portland, Maine. 144 pp. plus appendices.
    • Oechsli, L.M. 2000. Ex-urban development in the Rocky Mountain West: consequences for native vegetation, wildlife diversity, and land-use planning in Big Sky, Montana. M.Sc. Thesis. Montana State University, Bozeman. 73 p.
    • Peterson, Joel, and Michael R. Frisina, 1985, II Upland Game Bird Survey and Inventory, Region Three, Game Birds and Fur (Small Game) Survey and Inventory. Statewide Wildlife Survey and Inventory. W-130-R-16, Job No. II-3, July 1, 1984 - June 30, 1985.
    • Peterson, Joel, and Michael R. Frisina, 1986, II Upland Game Bird Survey and Inventory, Region Three, Game Birds and Fur (Small Game) Survey and Inventory. Statewide Wildlife Survey and Inventory. W-130-R-17, Job No. II-3, July 1, 1985 - June 30, 1986.
    • Peterson, Joel, and Michael R. Frisina, 1987, II Upland Game Bird and Inventory, Region Three, Game Birds and Fur (Small Game) Survey and Inventory. Statewide Wildlife Survey and Inventory. W-130-R-18, Job No. II-3, July 1, 1986 - June 30, 1987.
    • Reid, D. G., T. E. Code, A. C. H. Reid, and S. M. Herrero. 1994. Spacing, movements and habitat selection of the river otter in boreal Alberta. Can. J. Zool. 72:1314-1324.
    • Reid, F. 2006. Peterson Field Guide to Mammals of North America, 4th Edition. Houghton Mifflin Company: Boston and New York, 608 pp.
    • Reinhart, D.P. 1990. Grizzly bear habitat use on cutthroat trout spawning streams in tributaries of Yellowstone Lake. M.Sc. Thesis. Bozeman, MT: Montana State University. 128 p.
    • Rust, H. J. 1946. Mammals of northern Idaho. J. Mammal. 27(4): 308-327.
    • Stangl, J. M. 1994. Effects of monitoring effort and recreation patterns on temporal and spatial activities of breeding Bald Eagles. M.Sc. Thesis. Bozeman, MT: Montana State University. . 74 p.
    • 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.
    • Thompson, W.K. 1949. A study of marten in Montana. Proc. West. Assoc. State Game and Fish Comm. 29:181-188.
    • Tumlinson, R., and S. Shalaway. 1985. An Annotated Bibliography on the North American River Otter, Lutra canadensis. Oklahoma Coop. Fish and Wildl. Res. Unit, Oklahoma State Univ., Stillwater.
    • Tweten, R.G. 1984. Baseline survey of furbearing mammals within the South Fork drainage Sun River, Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 63 p.
    • USDI Fish and Wildlife Service., 1961, A Detailed report on fish and wildlife resources affected by McNamara Dam and Reservoir, Blackfoot River Project, Montana. June 1961.
    • Waller, A. J. 1992. Seasonal habitat use of river otters in northwestern Montana. M.S. thesis. University of Montana, Missoula. 75 pp.
  • Web Search Engines for Articles on "Northern River Otter"
  • Additional Sources of Information Related to "Mammals"
Login Logout
Citation for data on this website:
Northern River Otter — Lontra canadensis.  Montana Field Guide.  .  Retrieved on , from