River Otter

Four river otters resting on the snow
The waterproof pelt of river otters protects them from the cold winters


Black track of a river otter
River otter track

Scientific Name

Lontra canadensis


  • 40–54 inches long, 10–30 pounds.
  • Sleek, cylindrical body; small head; tail nearly one third of the body and tapers to a point; feet webbed; claws short; fur is dark dense brown.
  • Ears and nostrils close when underwater; whiskers aid in locating prey.


  • Most aquatic member of weasel family; generally found near water.
  • Eat crayfish and fish; also frogs, turtles, sometimes young muskrats or beavers.


  • Active year-round. Mostly crepuscular but have been seen at all times of the day.
  • Breed in late March through April; one litter of two young per year. Females and offspring remain together until next litter; may temporarily join other family groups.
  • Can swim underwater up to 6 miles per hour and for 2–3 minutes at a time.
  • Not agile or fast on land unless they find snow or ice, then can move rapidly by alternating hops and slides; can reach speeds of 15 miles per hour.
  • May move long distances between waterbodies.


Crait, J.R. et al. 2006. Late seasonal breeding of river ot- ters in Yellowstone National Park. American Midland Naturalist 156: 189–192.

Crait, J.R. and M. Ben-David. 2006. River otters in Yellowstone Lake depend on a declining cutthroat trout population. Journal of Mammalogy. 87: 485–494.

A wolf standing on a snowy bank near brown grass howls

Home to the largest concentration of mammals in the lower 48 states.

Last updated: October 21, 2020

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Contact Info

Mailing Address:

PO Box 168
Yellowstone National Park, WY 82190-0168



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