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River Otter

Lontra canadensis

River otters have a long, streamlined body covered in dense brown fur. (Dan Dzurisin/ Flickr)
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River otters have a long, streamlined body covered in dense brown fur. (Dan Dzurisin/ Flickr)

The river otter is a large, brown, weasel-like mammal found along the shores of the Chesapeake Bay and lakes, streams, rivers and marshes throughout the Bay watershed.

Appearance:

  • Long, streamlined body
  • Dense brown fur
  • Golden or silvery brown throat and belly
  • Wide, rounded head with small ears and long, white whiskers
  • Webbed feet
  • Long tail that is thick at the base and tapers toward the tip
  • Tail can grow to 12-19 inches long
  • Grows to 26-40 inches long, not including the tail, and weighs up to 18 pounds
  • Males are approximately 17 percent larger than females

Habitat:

  • Found along the shores of the Chesapeake Bay and its lakes, streams, rivers and marshes
  • Semi-aquatic, meaning it spends time both on land and in the water
  • Makes a den with an underwater entrance in a stream bank, a natural hollow (such as under a log), or in another animal’s burrow
  • Mostly nocturnal, with peak activity from dawn to mid-morning and again in the evening

Range:

  • Found throughout the Chesapeake Bay watershed

Feeding:

  • Feeds mostly on fish but will also eat frogs, crabs, crayfish, and small mammals such as young muskrats
  • Uses its long whiskers to detect its prey underwater

Predators:

  • Sometimes preyed upon by larger animals such as birds of prey
  • Usually able to escape from predators because it is very aware of its surroundings and agile both on land and in the water

Voice:

  • Able to communicate with others by whistling, growling, chuckling and screaming

Reproduction and Life Cycle:

  • Breeds in late winter and early spring
  • Gestationperiod lasts 2 months, but young may not be born for up to one year after mating because of delayed implantation and development of the newly fertilized eggs
  • During the time between fertilization and development, the eggs receive just enough nutrients from the female to stay alive
  • The female gives birth to a litter of 1-4 young in a nesting chamber within her den
  • Young are born blind and fully furred. Their eyes open in one month.
  • Young are weaned at 3 months old and leave the den between 6 months and 1 year old
  • Reaches sexual maturity at 2-3 years old
  • Lives about 8-9 years in the wild

Other Facts:

  • Remarkable and graceful swimmer that can remain submerged for several minutes, dive to 55 feet and swim up to a quarter-mile underwater
  • Equally comfortable on land and in the water. River otters may travel several miles over land to another stream or lake.
  • Playful and energetic, river otters often create “rolling spots” where they roll and tumble with each other. They will also slide into the water on paths of snow, dirt or ice.

Sources and Additional Information:

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