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Wildlife, Animals, and Plants
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Introductory
WILDLIFE SPECIES: Lutra canadensis | River Otter
ABBREVIATION :
LUCA
COMMON NAMES :
river otter
northern river otter
Canadian otter
land otter
fish otter
TAXONOMY :
The currently accepted scientific name for the river otter is Lutra
canadensis Schreber. (Lutrinae). Nineteen subspecies have been
recognized by Hall and Kelson [10] and are listed below:
Lutra canadensis ssp. canadensis Schreber
Lutra canadensis ssp. brevipilosus Grinnell
Lutra canadensis ssp. chimo Anderson
Lutra canadensis ssp. degener Bangs
Lutra canadensis ssp. evexa Goldman
Lutra canadensis ssp. extera Goldman
Lutra canadensis ssp. interior Swenk
Lutra canadensis ssp. kodiacensis Goldman
Lutra canadensis ssp. lataxina F. Cuvier
Lutra canadensis ssp. nexa Goldman
Lutra canadensis ssp. optiva Goldman
Lutra canadensis ssp. pacifica Rhoads
Lutra canadensis ssp. periclyzomae Elliot
Lutra canadensis ssp. preblei Goldman
Lutra canadensis ssp. sonora Rhoads
Lutra canadensis ssp. texensis Goldman
Lutra canadensis ssp. vaga Bangs
Lutra canadensis ssp. vancouverensis Goldman
Lutra canadensis ssp. yukonensis Goldman
A taxonomic revision of the Lutrinae was done by van Zyll de Jong, who
recommended consolidating the above nineteen subspecies and the Prince
of Wales Island form (Lutra mira Goldman) into seven subspecies of Lutra
canadensis, but leaving the southern river otter (Lutra annectens) as a
separate species [4].
ORDER :
Carnivora
CLASS :
Mammal
FEDERAL LEGAL STATUS :
See OTHER STATUS
OTHER STATUS :
Lutra canadensis sonora is federally listed as a Category 2 subspecies
[24].
The river otter is state-listed as endangered in Nebraska [23], Illinois
[21], and Colorado and threatened in South Dakota [22]. Region 3 of the
U.S. Forest Service lists it as a sensitive species. Montana lists the
otter as a furbearer, and imposes a one-otter limit per season [6]. The
inclusion of the taxa Lutrinae in Appendix II of the Convention on
International Trade in Endangered Species in 1977 required that the
river otter be managed to ensure that stable or increasing populations
persist. States must provide the U.S. Endangered Species Scientific
Authority with information that justifies current river otter management
[19].
COMPILED BY AND DATE :
Julie L. Tesky, June 1993
LAST REVISED BY AND DATE :
NO-ENTRY
AUTHORSHIP AND CITATION :
Tesky, Julie L. 1993. Lutra canadensis. In: Remainder of Citation
WILDLIFE DISTRIBUTION AND OCCURRENCE
WILDLIFE SPECIES: Lutra canadensis | River Otter
GENERAL DISTRIBUTION :
The river otter historically occurred over much of the North American
continent. Present distribution of the river otter extends from 25
degrees N. in Florida to beyond 70 degrees N. in Alaska, and from
eastern Newfoundland to the Aleutian Islands [4]. River otters have
been extirpated or are rare in Arizona, Colorado, Indiana, Iowa, Kansas,
Kentucky, Nebraska, New Mexico, North Dakota, Ohio, Oklahoma, South
Dakota, Tennessee, Utah, and West Virginia. They are still relatively
abundant along the coasts of the Atlantic Ocean and the Gulf of Mexico,
throughout the Pacific Northwest and Great Lakes states, and across most
of Canada and Alaska. Populations are listed as stable or increasing in
Alabama, Alaska, Arkansas, Connecticut, Delaware, Florida, Georgia,
Idaho, Louisiana, Maryland, Massachusetts, Michigan, Minnesota,
Mississippi, Montana, New Hampshire, New York, North Carolina, Oregon,
Rhode Island, Texas, Vermont, Washington, and Wisconsin [4].
ECOSYSTEMS :
FRES10 White-red-jack pine
FRES11 Spruce-fir
FRES17 Elm-ash-cottonwood
FRES18 Maple-beech-birch
FRES19 Aspen-birch
FRES20 Douglas-fir
FRES21 Ponderosa pine
FRES22 Western white pine
FRES23 Fir-spruce
FRES28 Western hardwoods
FRES36 Mountain grasslands
FRES37 Mountain meadows
FRES41 Wet grasslands
STATES :
| AL |
AK |
AZ |
AR |
CA |
CO |
CT |
DE |
FL |
GA |
| ID |
IL |
IN |
IA |
KS |
KY |
LA |
ME |
MD |
MA |
| MI |
MN |
MS |
MO |
MT |
NE |
NV |
NH |
NJ |
NM |
| NY |
NC |
ND |
OH |
OK |
OR |
PA |
RI |
SC |
SD |
| TN |
TX |
UT |
VT |
VA |
WA |
WV |
WI |
WY |
| AB |
BC |
MB |
NB |
NF |
NT |
NS |
ON |
PE |
PQ |
| SK |
YK |
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BLM PHYSIOGRAPHIC REGIONS :
1 Northern Pacific Border
2 Cascade Mountains
3 Southern Pacific Border
4 Sierra Mountains
5 Columbia Plateau
6 Upper Basin and Range
7 Lower Basin and Range
8 Northern Rocky Mountains
9 Middle Rocky Mountains
10 Wyoming Basin
11 Southern Rocky Mountains
12 Colorado Plateau
13 Rocky Mountain Piedmont
14 Great Plains
15 Black Hills Uplift
16 Upper Missouri Basin and Broken Lands
KUCHLER PLANT ASSOCIATIONS :
K005 Mixed conifer forest
K011 Western ponderosa forest
K012 Douglas-fir forest
K015 Western spruce - fir forest
K020 Spruce - fir - Douglas-fir forest
K021 Southwestern spruce - fir forest
K025 Alder - ash forest
K026 Oregon oakwoods
K028 Mosaic of K002 and K026
K030 California oakwoods
K047 Fescue - oatgrass
K049 Tule marshes
K050 Fescue - wheatgrass
K051 Wheatgrass - bluegrass
K063 Foothills prairie
K073 Northern cordgrass prairie
K078 Southern cordgrass prairie
K080 Marl - everglades
K092 Everglades
K093 Great Lakes spruce - fir forest
K094 Conifer bog
K095 Great Lakes pine forest
K096 Northeastern spruce - fir forest
K097 Southeastern spruce - fir forest
K098 Northern floodplain forest
K101 Elm - ash forest
K106 Northern hardwoods
K107 Northern hardwoods - fir forest
K108 Northern hardwoods - spruce forest
SAF COVER TYPES :
16 Aspen
18 Paper birch
19 Gray birch - red maple
20 White pine - northern red oak - red maple
24 Hemlock - yellow birch
25 Sugar maple - beech - yellow birch
30 Red spruce - yellow birch
31 Red spruce - sugar maple - beech
35 Paper birch - red spruce - balsam fir
39 Black ash - American elm - red maple
51 White pine - chestnut oak
62 Silver maple - American elm
93 Sugarberry - American elm - green ash
95 Black willow
202 White spruce - paper birch
204 Black spruce
203 Balsam poplar
210 Interior Douglas-fir
212 Western larch
217 Aspen
222 Black cottonwood - willow
235 Cottonwood - willow
241 Western live oak
244 Pacific ponderosa pine - Douglas-fir
245 Pacific ponderosa pine
246 California black oak
249 Canyon live oak
252 Paper birch
255 California coast live oak
SRM (RANGELAND) COVER TYPES :
NO-ENTRY
PLANT COMMUNITIES :
River otters inhabit a variety of riparian plant communities. These
communities are often dominated by willows (Salix spp.), cottonwoods
(Populus spp.), birches (Betula spp.), and spruce (Picea spp.). Other
vegetation common in river otter habitats includes cattails (Typha
spp.), red-osier dogwood (Cornus sericea), black hawthorn (Crataegus
douglassi), common snowberry (Symphoricarpos albus), grasses, horsetails
(Equisetum spp.), bulrushes (Scirpus spp.), and sedges (Carex spp.)
[3,6,19].
REFERENCES :
NO-ENTRY
BIOLOGICAL DATA AND HABITAT REQUIREMENTS
WILDLIFE SPECIES: Lutra canadensis | River Otter
TIMING OF MAJOR LIFE HISTORY EVENTS :
Breeding - River otters breed in late winter or early spring; the
breeding season is spread over a period of 3 months or longer [1,4].
Gestation period and litter size - There is much discrepancy in the
literature regarding the length of gestation in the river otter.
Gestation periods of 288 to 375 days have been reported. The extreme
length of gestation is due to a process called "delayed implantation",
wherein the development of the blastocyst is arrested for a period of
time before it implants into the uterine wall. Litters are generally
born from November through May. In northwestern North America, river
otters generally give birth from March through May following an average
delay of 9 months and an actual gestation of about 62 days [6]. Litter
size ranges from one to six, with two to four young most common [4].
Pup development - River otter pups are born helpless. They begin to
open their eyes by age 21 to 35 days; by 25 to 42 days pups begin
playing. River otter pups are introduced to water by age 48 days and
may venture out of the den on their own by the age of 59 to 70 days.
Weaning occurs at about 91 days of age [4].
Age at sexual maturity - Female river otters normally become sexually
mature when they are about 2 years old, but may or may not breed at that
time. Female river otters may not breed every year [6,14]. Although
male river otters also become sexually mature at about 2 years of age,
they may not become successful breeders until they reach 5 to 7 years
[4].
Life span - River otters have lived at least 16 years in captivity [1].
River otters are primarily nocturnal, but may be active in the early
morning and late afternoon in remote areas. They are active all winter
except during the most severe periods, when they take shelter for a few
days [1].
PREFERRED HABITAT :
River otters are adapted to a variety of aquatic habitats from marine
environments to high-elevation mountain lakes. Optimum habitat for
river otters includes slow-moving water with deep pools, abundant
riparian vegetation, and plentiful fish [6]. River otters are generally
most abundant along food-rich coastal areas, such as the lower portions
of streams and rivers and in estuaries, and in areas having extensive
nonpolluted waterways [4]. In Canada, they occur north beyond the tree
line in tundra lakes and streams [1].
Melquist and Hornocker [14] found that in west-central Idaho, river
otters prefer valley habitats to mountain habitats, and prefer
streamassociated habitats to lake, reservoir, and pond habitats.
Mountain lakes and streams were used most often during the fall. Most
river otters lived entirely in the valleys, and no otters lived solely
in the mountains. The use of lakes, reservoirs, and ponds was greatest
during the winter. Mudflats and associated open marshes, swamps, and
backwater sloughs were used most often in summer [14].
River otter habitat is generally limited to open water during the
winter months. Outflows from lakes are favored habitat at this time.
In late winter, water levels usually drop below ice levels in rivers and
lakes, leaving a layer of air that allows river otters to travel and
hunt under the ice [16].
COVER REQUIREMENTS :
River otter habitat must provide adequate escape cover, rest sites, and
den sites. Rather than excavate their own dens, river otters use dens
dug by other animals, or natural shelters. They commonly use hollow
trunks of large trees, beaver (Castor canadensis) or nutria (Myocastor
coypus) dens, hollow logs, log jams, drift piles, jumbles of loose
rocks, abandoned or unused boathouses, and duck blinds [4].
Occasionally river otters occupy large, bulky, open nests of grasses in
marshes or riverbank thickets [1]. Understory bank cover is also
important to river otters. In a study of river otter habitat in
northwestern Montana, areas with less than 25 percent understory bank
cover were used significantly less than expected based on availability
[6]. Stream habitats generally provide more adequate escape cover and
shelter and less human disturbance than pond, lake, and reservoir
habitats [16].
FOOD HABITS :
The typical diet of river otters consists primarily of fish, but also
includes crustaceans (primarily crayfish), amphibians, insects, birds,
mammals, and plants [4,5,13]. Although a wide variety of fish species
are eaten by river otters, some species of fish are more vulnerable to
river otter predation. Slow-swimming fish species are generally
selected by river otters more often than fast-swimming fishes. Also
important are fish species that are abundant and found in large schools
[4]. Fishes often eaten by river otters include suckers (Catostomus
spp.), redhorses (Moxostoma spp.), carp (Cyprinus spp.), chubs
(Semotilus spp.), daces (Phinichthys spp.), shiners (Notropis spp.),
squawfish (Ptychocheilus spp.), bullheads and catfish (Ictalurus spp.),
sunfish (Lepomis spp.), darters (Etheostoma spp.), and perch (Perca
spp.). Crayfish (Cambarus spp., Pacifasticus spp., and others) also
comprise a major portion of the river otter's diet [1,4].
Waterfowl and rails comprise an important part of the river otter diet
in the Pacific Coast states and in many other regions. Freshwater
mussels (Anodonta californiensia), freshwater periwinkles (Oxytrema
silicula), and unidentified clams and snails have been reported in the
river otter's diet but are not important food items [4]. River otters
may kill young beavers found alone in a lodge [1].
PREDATORS :
Although essentially safe from predators while in water, river otters
are considerably more vulnerable when they travel overland between
lakes, ponds, and steams [14]. Bobcats (Felis rufus), dogs (Canis
familiaris), coyotes (C. lutrans), foxes, gray wolves (C. lupus), and
American alligators (Alligator mississippiensis) have all been reported
to kill river otters [4,14,15]. In addition, it is likely that other
predators, including cougars (F. concolor), black bears (Ursus
americanus), American crocodiles (Crocodylus acutus), and some large
raptors, also kill river otters on occasion. No predator has been shown
to have a serious impact on river otter populations, and most predation
is probably directed toward young river otters [4].
MANAGEMENT CONSIDERATIONS :
River otters have often been blamed for serious depredation of game
fish, particularly trout. Food habit studies, however, have all
indicated that the bulk of the river otter diet consists of nongame fish
species. In many circumstances, river otters are beneficial to game
fish populations because they remove nongame fish that would otherwise
compete with game fish for food [4]. River otters, however, may
occasionally cause severe depredation in fish hatcheries [1,4].
River otters have been extirpated or reduced in many areas due to human
encroachment, habitat destruction, and overharvest [8]. River otters
are relatively abundant in major nonpolluted river systems and in the
lakes and tributaries that feed them. They are scarce, however, in
heavily settled areas, particularly if the waterways are polluted. In
Maryland, no river otters occur in waters altered by acidic mine
drainages. The disappearance of river otters from West Virginia and
parts of Tennessee and Kentucky has been attributed to increased acidity
of ground water due to mining operations [4]. Little research has been
done in evaluating the range of water quality that otters will tolerate
[4]
The most readily apparent human impact on river otters results from
trappers harvesting otters for their fur. The river otter has been an
economically important furbearing species since Europeans first arrived
in North America [4]. Habitat destruction has also resulted in a
decline in river otter populations. Some causes of river otter habitat
destruction include the development of waterways for economic or
recreational purposes, destruction of riparian habitat for homesites or
farmland, and a decline in water quality because of increased siltation
and/or pesticide residues in runoff [4,6,16]. Pesticide residues
including mercury, DDT and its metabolites, and Mirex have been reported
in river otter tissues [4].
Roads and railroad tracks that parallel or cross streams are probably
responsible for a considerable number of river otter deaths each year.
This is an important consideration in mountainous states where roads are
constructed along stream courses [14].
Several researchers have associated good river otter habitat with the
activities of beavers. River otter population dynamics may be
influenced not only by beaver trapping but also by wide fluctuations in
beaver numbers and subsequent habitat changes. In the western United
States, with its widely separated waterways and large variations in
flow, beaver-created habitat may be critical to river otter denning and
foraging [6].
A variety of internal parasites affect river otters. Of these, two
roundworms (Stronguloides lutrae and Gnathostoma miyazakii) may cause
serious pathological damage. River otters are also susceptible to
canine distemper, jaundice, hepatitis, and feline panleucopenia [4].
In recent years several states have transplanted river otters in an
attempt to establish or reestablish breeding populations [17].
REFERENCES :
NO-ENTRY
FIRE EFFECTS AND USE
WILDLIFE SPECIES: Lutra canadensis | River Otter
DIRECT FIRE EFFECTS ON ANIMALS :
No information was found in the literature regarding the direct effect
of fire on river otters; however, they can probably easily escape fire.
The aquatic habitats in which they occur will generally provide good
escape cover.
HABITAT RELATED FIRE EFFECTS :
The short-term effects of a riparian fire may affect the river otter's
food supply. Removal of streamside vegetation increases the risk of
streambank erosion and raises stream temperatures, both of which could
potentially reduce fish populations in the stream. However, the
long-term effect of fire on fish populations could be benefical. Fire
thins and removes conifers along streams, stimulates growth of deciduous
vegetation. This provides cover and shading, and fosters development of
terrestrial insects important in the diet of fishes [20].
Additionally, fire occurring in riparian areas indirectly benefits river
otters by benefiting beavers [11]. As stated in MANAGEMENT
CONSIDERATIONS, beaver activities help create suitable habitat for river
otters.
FIRE USE :
When burning marshes, partial burns are more desirable than complete
burns. The unburned portions of the marsh provide cover for river
otters [20].
REFERENCES :
NO-ENTRY
REFERENCES
WILDLIFE SPECIES: Lutra canadensis | River Otter
REFERENCES :
1. Banfield, A. W. F. 1974. The mammals of Canada. Toronto, ON: University
of Toronto Press. 438 p. [21084]
2. Bernard, Stephen R.; Brown, Kenneth F. 1977. Distribution of mammals,
reptiles, and amphibians by BLM physiographic regions and A.W. Kuchler's
associations for the eleven western states. Tech. Note 301. Denver, CO:
U.S. Department of the Interior, Bureau of Land Management. 169 p.
[434]
3. Chabreck, Robert H. 1971. Ponds and lakes of the Louisiana coastal
marshes and their value to fish and wildlife. Proceedings, 25th Annual
Conference of Southeastern Association of Game and Fish Commissioners:
206-215. [14961]
4. Chapman, Joseph A.; Feldhamer, George A., eds. 1982. Wild mammals of
North America. Baltimore, MD: The Johns Hopkins University Press. 1147
p. [21085]
5. Davis, Harry G.; Aulerich, Richard J.; Bursian, Steven J.; [and others].
1992. Feed consumption and food transit time in northern river otters
(Lutra canadensis). Journal of Zoo and Wildlife Medicine. 23(2):
241-244. [18438]
6. Dronkert-Egnew, Ana E. 1991. River otter population status and habitat
use in northwestern Montana. Missoula, MT: Univeristy of Montana. 112 p.
Thesis. [20339]
7. Eyre, F. H., ed. 1980. Forest cover types of the United States and
Canada. Washington, DC: Society of American Foresters. 148 p. [905]
8. Finch, Deborah M. 1992. Threatened, endangered, and vulnerable species
of terrestrial vertebrates in the Rocky Mountain Region. Gen. Tech. Rep.
RM-215. Fort Collins, CO: U.S. Department of Agriculture, Forest
Service, Rocky Mountain Forest and Range Experiment Station. 38 p.
[18440]
9. Garrison, George A.; Bjugstad, Ardell J.; Duncan, Don A.; [and others].
1977. Vegetation and environmental features of forest and range
ecosystems. Agric. Handb. 475. Washington, DC: U.S. Department of
Agriculture, Forest Service. 68 p. [998]
10. Hall, E. Raymond; Kelson, Keith R. 1959. The mammals of North America,
Volume II. New York: The Ronald Press Company. 79 p. [21460]
11. Kelleyhouse, David G. 1979. Fire/wildlife relationships in Alaska. In:
Hoefs, M.; Russell, D., eds. Wildlife and wildfire: Proceedings of
workshop; 1979 November 27-28; Whitehorse, YT. Whitehorse, YT: Yukon
Wildlife Branch: 1-36. [14071]
12. Kuchler, A. W. 1964. Manual to accompany the map of potential vegetation
of the conterminous United States. Special Publication No. 36. New York:
American Geographical Society. 77 p. [1384]
13. Meehan, William R. 1974. The forest ecosystem of southeast Alaska: 4.
Wildlife habitats. Gen. Tech. Rep. PNW-16. Portland, OR: U.S. Department
of Agriculture, Forest Service, Pacific Northwest Forest and Range
Experiment Station. 32 p. [13479]
14. Melquist, Wayne E.; Hornocker, Maurice G. 1983. Ecology of river otters
in west central Idaho. Wildlife Monographs. 83: 1-60. [19356]
15. Route, William T.; Peterson, Rolf O. 1991. An incident of wolf, Canis
lupus, predation on a river otter, Lutra canadensis, in Minnesota.
Canadian Field-Naturalist. 105(4): 567-568. [19821]
16. Spowart, Richard A.; Samson, Fred B. 1986. Carnivores. In: Cooperrider,
Allan Y.; Boyd, Raymond J.; Stuart, Hanson R., eds. Inventory and
monitoring of wildlife habitat. Denver, CO: U.S. Department of the
Interior, Bureau of Land Management, Service Center: 475-496. [13526]
17. Tango, Peter J.; Michael, Edwin D.; Cromer, Jack I. 1991. Mating and
first-season births in interstate transplanted river otters, Lutra
canadensis (Carnivora: Mustelidae). Brimleyana. 17: 53-55. [20686]
18. Van Gelden, Richard George. 1982. Mammals of the National Parks.
Baltimore, MD: Johns Hopkins University Press. 310 p. [20893]
19. Waller, Amy Johnston. 1992. Seasonal habitat use of river otters in
northwestern Montana. Missoula, MT: University of Montana. 75 p. Thesis.
[20659]
20. Wright, Henry A.; Bailey, Arthur W. 1982. Fire ecology: United States
and southern Canada. New York: John Wiley & Sons. 501 p. [2620]
21. Herkert, J. R., ed. 1992. Endangered and threatened species of Illinois:
status and distribution. Volume 2--Animals. Springfield, IL: Illinois
Endangered Species Protection Board. 142 p. [23799]
22. South Dakota Department of Game, Fish and Parks. 1994. Fragile legacy:
Endangered, threatened and rare animals of South Dakota. Pierre, SD:
South Dakota Department of Game, Fish, and Parks, Wildlife Division. 55
p. [24341]
23. Wingfield, Greg. 1992. Nebraska's vanishing species. Lincoln, NE:
Nebraska Game and Parks Commission, Wildlife Division, [Nebraskaland
Magazine]. 15 p. [24344]
24. U.S. Department of the Interior, Fish and Wildlife Service. 1994.
Endangered and threatened wildlife and plants; animal candidate review
for listing as endangered or threatened species; proposed rule. 50 CFR
Part 17. Tuesday, November 15, 1994. Federal Register. 59(219):
58982-59028. [24357]
Index
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Related categories for Wildlife Species: Lutra canadensis
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