River otter

The North American River Otter is a semi-aquatic member of the weasel family found in lakes, rivers, streams, wetlands and coastal areas across the United States and Canada. Concentrations are highest in the southeast, northeast, and pacific northwest, and sparse across interior states. Reintroduction efforts are taking hold in the Rocky Mountain region where trapping depleted numbers in the 1800s.

River Otter - Hoh River

While river otters have adapted to various habitats, good water quality and abundant food are essential to their success. Population estimates are difficult to attain, but conservation groups believe 100,000 exist in the wild.

General Description: River otter measure 3.2 - 3.7' long including the tail, and 11 - 30 lbs (average female-male). Tails typically comprise 1/3 of its overall length. River otters live 10-12 years in the wild, and up to 25 years in captivity. Diet River otters primarily eat fish, but will opportunistically feed on crustaceans, mollusks, crabs, frogs, turtles, rodents and birds. They have high a metabolism to match their energetic and cold water lifestyle, which requires they eat 15% of their body weight daily.

River otters have thick, water-repellent fur and long, hydrodynamic bodies. A strong, flattened tail and webbed feet propel them through the water as ears and nostrils close to keep water out. Long facial whiskers help them identify objects in murky water.

River otters can stay underwater 4-6 minutes and dive up to 60'. They're less graceful on land but still quite effective with a lumbering gate. River otters swim 6-8 mph but can run 15 mph over short distances.Though swimming is preferred, river otter will travel some distance by land and are known to use the same pathways over and over.

Behavior: River otters live in small social groups comprised of a mother and pups, or individual males. They dwell in multi-channel burrows adjacent to water, typically with access from within the burrow. River otters are famously playful during the day, and hunt mainly at night.

river otter den

Reproduction: River otter mating season occurs February-April, a window shaped largely by climate and latitude. Egg implantation is delayed up to 10 months, and pups are typically born the following year after a 60-65 gestation. Females give birth in underground dens and execute all parenting duties (males do not assist). Pups open their eyes after 5 weeks, begin swimming within 2 months, are weaned after 4 months, and reach sexual maturity in two years. Pups typically remain with the mother for a year, or until the next litter arrives.