River Otter
Lontra canadensis

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

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A river otter swims at Trap Pond State Park in Sussex County, Del., on Oct. 6, 2017. The park holds remnants of a vast cypress swamp that covered roughly 50,000 acres of southern Delaware before colonial times. The swamp was decimated by logging and several fires caused by the draining of wetlands. (Photo by Will Parson/Chesapeake Bay Program) USAGE REQUEST INFORMATION The Chesapeake Bay Program's photographic archive is available for media and non-commercial use at no charge. To request permission, send an email briefly describing the proposed use to requests@chesapeakebay.net. Please do not attach jpegs. Instead, reference the corresponding Flickr URL of the image. A photo credit mentioning the Chesapeake Bay Program is mandatory. The photograph may not be manipulated in any way or used in any way that suggests approval or endorsement of the Chesapeake Bay Program. Requestors should also respect the publicity rights of individuals photographed, and seek their consent if necessary.

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Appearance

The river otter has a long, streamlined body with dense brown fur. Its throat and belly are golden or silvery brown. It has a wide, round head with small ears and long, white whiskers. Its feet are webbed. It has a long tail that is thick at the base, and thinner toward the tip and grows to 12 to 19 inches in length. River otters grow 26 to 40 inches in length, not including the tail, and weigh up to 18 pounds. Males are approximately 17 percent larger than females.

Feeding

River otters feed mostly on fish but will also eat frogs, crabs, crayfish, and small mammals such as young muskrats. They uses their long whiskers to detect prey underwater.

Predators

Sometimes preyed upon by larger animals such as birds of prey. River otters are usually able to escape from predators because they are very aware of their surroundings and agile both on land and in the water.

Voice

The river otter is able to communicate with others by whistling, growling, chuckling and screaming.

Reproduction and Life Cycle

Breeding occurs in late winter and early spring. Gestation 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 to 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. River otters reach sexual maturity at 2 to 3 years old and live about 8 to 9 years in the wild.

Did You Know?

  • Otters are graceful swimmers that can remain submerged for several minutes, dive to 55 feet and swim up to a quarter-mile underwater.
  • They are semi-aquatic, spending time both on land and in the water. They make dens with an underwater entrance in a stream bank, a natural hollow (such as under a log), or in another animal’s burrow.
  • Otters are mostly nocturnal, with activity peaking from dawn to mid-morning and again in the evening.
  • 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

Tags:
Mammals Semi-Aquatic Mammals Open & Shallow Waters