North American River Otter Facts

Scientific Name: Lontra canadensis

North American river otter
The North American river otter is a semiaquatic mammal.

 Jouko van der Kruijssen / Getty Images

The North American river otter (Lontra canadensis) is a semiaquatic mammal in the weasel family. While it may simply be called the "river otter" in North America (to distinguish it from the sea otter) there are other river otter species throughout the world. Despite its common name, the North American river otter is equally comfortable in either coastal marine or freshwater habitats.

Fast Facts: North American River Otter

  • Scientific Name: Lontra canadensis
  • Common Names: North American river otter, northern river otter, common otter
  • Basic Animal Group: Mammal
  • Size: 26-42 inches plus a 12-20 inch tail
  • Weight: 11-31 pounds
  • Lifespan: 8-9 years
  • Diet: Carnivore
  • Habitat: Watersheds of North America
  • Population: Abundant
  • Conservation Status: Least Concern

Description

The North American river otter's body is built for streamlined swimming. It has a stocky body, short legs, webbed feet, and a long tail. In contrast to the European otter, the North American river otter has a longer neck and narrower face. The otter closes its nostrils and small ears when submerged. It uses its long vibrissae (whiskers) to find prey in murky water.

North American river otters weigh 11 to 31 pounds and range from 26 to 42 inches long plus a 12 to 20 inch tail. Otters are sexually dimorphic, with males about 5% larger than females. Otter fur is short and ranges in color from light brown to black. White-tipped hairs are common in older otters.

River otter swimming
River otters use their tails as rudder while swimming. Hailshadow / Getty Images

Habitat and Distribution

North American river otters live near permanent watersheds throughout North America, from Alaska and northern Canada south to the Gulf of Mexico. Typical habitats include lakes, rivers, marshes, and coastal shorelines. Although largely exterminated in the Midwest, reintroduction programs are helping river otters reclaim part of their original range.

Diet

River otters are carnivores that hunt fish, crustaceans, frogs, salamanders, waterfowl and their eggs, aquatic insects, reptiles, mollusks, and small mammals. They sometimes eat fruit, but avoid carrion. During winter, otters are active during the daytime. In warmer months, they are most active between dusk and dawn.

Behavior

North American river otters are social animals. Their basic social unit consists of an adult female and her offspring. Males also group together. Otters communicate by vocalization and scent marking. Young otters play to learn survival skills. River otters are excellent swimmers. On land they walk, run, or slide across surfaces. They may travel as much as 26 miles in a single day.

Reproduction and Offspring

North American river otters breed between December and April. Embryo implantation is delayed. Gestation lasts 61 to 63 days, but young are born 10 to 12 months after mating, between February and April. Females seek dens made by other animals for giving birth and raising young. Females give birth and raise their pups without aid from their mates. A typical litter ranges from one to three pups, but as many as five pups may be born. Otter pups are born with fur, but are blind and toothless. Each pup weighs about 5 ounces. Weaning occurs at 12 weeks. Offspring venture out on their own before their mother gives birth to her next litter. North American river otters reach sexual maturity at two years of age. Wild otters typically live 8 or 9 years, but may live 13 years. River otters live 21 to 25 years in captivity.

Baby river otter
Baby river otter. ArendTrent / Getty Images

Conservation Status

The IUCN classifies North American river otter conservation status as "least concern." For the most part, the species population is stable and otters are being reintroduced into areas from which they vanished. However, river otters are listed on Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) because the species may become endangered if trade is not closely regulated.

Threats

River otters are subject to predators and disease, but human activities are their greatest threat. Otters are highly susceptible to water pollution, including oil spills. Other important threats include habitat loss and degradation, illegal hunting, vehicle accidents, trapping, and entanglement in fishnets and lines.

River Otters and Humans

River otters are hunted and trapped for their fur. Otters pose no threat to humans, but in rare cases they have been known to attack dogs.

Sources

  • Kruuk, Hans. Otters: ecology, behaviour and conservation. Oxford: Oxford University Press, 2006. ISBN 0-19-856586-0.
  • Reid, D.G.; T.E. Code; A.C.H. Reid; S.M. Herrero "Food habits of the river otter in a boreal ecosystem". Canadian Journal of Zoology. 72 (7): 1306–1313, 1994. doi:10.1139/z94-174
  • Serfass, T., Evans, S.S. & Polechla, P. Lontra canadensis. The IUCN Red List of Threatened Species 2015: e.T12302A21936349. doi:10.2305/IUCN.UK.2015-2.RLTS.T12302A21936349.en
  • Toweill, D.E. and J.E. Tabor. "The Northern River Otter Lutra canadensis (Schreber)". Wild mammals of North America (J.A. Chapman and G.A. Feldhamer ed.). Baltimore, Maryland: Johns Hopkins University Press, 1982.
  • Wilson, D.E.; Reeder, D.M., eds. Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press, 2005. ISBN 978-0-8018-8221-0.