North American river otters communicate in a variety of ways. They vocalize with whistles, growls, chuckles, and screams. They also scent mark using paired scent glands near the base of their tails or by urinating/defecating on vegetation within their home range. These glands produce a very strong, musky odor. They also use touch and communicate through posture and other body signals.
North American river otters perceive their environment through vision, touch, smell, and hearing. Their large and abundant whiskers are very sensitive and are important in tactile sensation. These whiskers are used extensively in hunting, as smell, vision, and hearing are diminished in the water.
Communication Channels: visual ; tactile ; acoustic ; chemical
Other Communication Modes: scent marks
Perception Channels: visual ; tactile ; acoustic ; chemical
Northern river otters are listed in Appendix II of CITES. Populations were once extirpated through many parts of their range, especially around heavily populated areas in the midwestern and eastern United States. Population trends have stabilized in recent years and reintroduction and conservation efforts have resulted in recolonization of areas where they were previously extirpated. Northern river otter populations are still considered vulnerable or imperiled throughout much of their range in midwestern United States and the Appalachian mountains. They are presumed extirpated in New Mexico and population status in South Carolina and Florida has not yet been reviewed.
US Federal List: no special status
CITES: appendix ii
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
North American river otters generally do not have adverse affects on humans.
North American river otters are important parts of healthy, aquatic ecosystems.
North American river otters have been hunted for many years for their attractive and durable fur. In the 1983-84 hunting season, 33,135 otters were taken with an average selling price of $18.71 per pelt. Otters are stll an important source of income for many people in Canada and the western United States. River otters also eat "trash fish" that compete with more economically desirable game fish.
Positive Impacts: body parts are source of valuable material
North American river otters are important predators of fish and aquatic invertebrates.
North American river otters eat mainly aquatic organisms such as amphibians, fish, turtles, crayfish, crabs, and other invertebrates. Birds, their eggs, and small terrestrial mammals are also eaten on occasion. They sometimes eat aquatic plants.
Prey is captured with the mouth, and mainly slow, non-game fish species are taken, e.g., suckers. The otter's long whiskers are used to detect organisms in the substrate and the dark water. Prey is eaten immediately after capture, usually in the water, although larger prey is eaten on land.
Animal Foods: birds; mammals; amphibians; fish; eggs; insects; terrestrial non-insect arthropods; aquatic crustaceans
Plant Foods: leaves; roots and tubers; macroalgae
Primary Diet: carnivore (Piscivore , Eats non-insect arthropods)
North American river otters occur throughout Canada and the United States, except for areas of southern California, New Mexico, and Texas, and the Mohave desert of Nevada and Colorado. In Mexico they are found in the delta areas of the Rio Grande and Colorado river. Otters were locally extirpated from portions of their range but reintroduction and conservation efforts have helped stabilize populations.
Biogeographic Regions: nearctic (Native )
North American river otters are found anywhere there is a permanent food supply and easy access to water. They can live in freshwater and coastal marine habitats, including rivers, lakes, marshes, swamps, and estuaries. River otters can tolerate a variety of environments, including cold and warmer latitudes and high elevations. North American river otters seem to be sensitive to pollution and disappear from areas with polluted waters.
North American river otters build dens in the burrows of other mammals, in natural hollows, such as under a log, or in river banks. Dens have underwater entrances and a tunnel leading to a nest chamber that is lined with leaves, grass, moss, bark, and hair.
Habitat Regions: temperate ; terrestrial
Aquatic Biomes: lakes and ponds; rivers and streams; coastal
Wetlands: marsh ; swamp ; bog
Other Habitat Features: riparian ; estuarine
North American river otters can live up to 21 years in captivity. They normally live about 8 to 9 years in the wild.
Range lifespan
Status: captivity: 21 (high) years.
Typical lifespan
Status: wild: 8 to 9 years.
Average lifespan
Status: wild: 8-9 years.
North American river otters are semi-aquatic mammals, with long, streamlined bodies, thick tapered tails, and short legs. They have wide, rounded heads, small ears, and nostrils that can be closed underwater. The vibrissae are long and thick, reflecting their importance in sensory perception. The fur is dark brown to almost black above and a lighter color ventrally. The throat and cheeks are usually a golden brown. The fur is dense and soft, effectively insulating these animals in water. The feet have claws and are completely webbed. Body length ranges from 889 to 1300 mm and tail length from 300 to 507 mm. Weight ranges from 5 to 14 kg. Males average larger than females in all measurements.
Range mass: 5 to 14 kg.
Range length: 889 to 1300 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger
North American river otters are sometimes taken by bobcats, coyotes, birds of prey, alligators, and other large predators. They mainly escape predation through their agility in the water and on land, their vigilance, and their ability to fiercely defend themselves and their young.
Known Predators:
Males and females do not associate except during the mating season. Males often breed with several females, probably those whose home ranges overlap with their own.
Mating System: polygynous
Males and females come together to breed in late winter or early spring. Gestation lasts two months, but the young may be born up to a year after mating because these otters employ delayed implantation of the fertilized egg in the uterus. Births occur from November to May, with a peak in March and April. Females give birth to from 1 to 6 young per litter, with an average of 2 to 3, in a den near the water. They are born with fur, but are otherwise helpless. They open their eyes at one month of age and are weaned at about 3 months old. They begin to leave their natal range at from 6 months to a year old. Sexual maturity is reached at 2 to 3 years of age.
Breeding interval: Breeding occurs once yearly.
Breeding season: Mating occurs in late winter and early spring.
Range number of offspring: 1 to 6.
Average number of offspring: 2-3.
Average gestation period: 2 months.
Average weaning age: 3 months.
Range time to independence: 6 to 12 months.
Range age at sexual or reproductive maturity (female): 2 to 3 years.
Range age at sexual or reproductive maturity (male): 2 to 3 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); viviparous ; delayed implantation
Average birth mass: 140 g.
Average gestation period: 62 days.
Average number of offspring: 2.5.
Females give birth to, nurse, and care for their young in a den near the water. The young are weaned at about 3 months old and begin to leave their mother at 6 months old.
Parental Investment: altricial ; female parental care
