North American River Otter
North American river otters are found anywhere there is a permanent food supply and easy access to water. They can live in freshwater and coastal marine habitats, including rivers, lakes, marshes, swamps, and estuaries. River otters can tolerate a variety of environments, including cold and warmer latitudes and high elevations.
North American river otters build dens in the burrows of other mammals, in natural hollows, such as under a log, or in river banks. Dens have underwater entrances and a tunnel leading to a nest chamber that is lined with leaves, grass, moss, bark, and hair.
Adaptation to Habitat
River Otters have many adaptations which make them the ideal aquatic hunter. They have two different types of fur: an outer coat of guard hairs which works to protect an inner coat of short, dense, waterproof fur; the inner coat works to insulate them from the cold and traps air to help keep their skin dry. The River Otter's fur is dark brown on it's back and either light brown or gray on their stomachs. This coloration makes it harder for fish to see them from below.
The River Otter has four short, strong legs, webbed feet and a long tail it can use as a rudder. This, along with nostrils and ears that close automatically when under water, help make the otter a powerful, agile swimmer capable of chasing down even the fastest prey.
Did you know?
Females give birth to, nurse, and care for their young in a den near the water. The young are weaned at about 3 months old and begin to leave their mother at 6 months old.
North American river otters can live up to 21 years in captivity. They normally live about 8 to 9 years in the wild.
Individuals are solitary, except for females with their young. They are known as playful animals, exhibiting behaviors such as mud/snow sliding, burrowing through the snow, and waterplay. Many "play" activities actually serve a purpose. Some are used to strengthen social bonds, to practice hunting techniques, and to scent mark. North American river otters get their boundless energy from their very high metabolism, which also requires them to eat a great deal during the day.
They are excellent swimmers and divers, able to stay underwater for up to 8 minutes. They are also fast on land, capable of running at up to 18 mph (29 km/h). These otters normally hunt at night, but can be seen at all times of day.
Area Demise and Reintroduction
Historically, River Otters have inhabited most of North America. Unfortunately, the same dense fur that helps them survive in the wild also spelled their downfall. Unrestarined trapping in the early 19th Century devoured the River Otter population in the Smokies. After the last reliable sighting in 1936, 50 years would pass before the streams and rivers of the Smokies would be visited by another River Otter. Since 1986, 137 otters have been released in order to repopulate the water ways of the Smokies, and, if you're lucky, you may see one frolickiong in their native aquatic habitat.
North American river otters eat mainly aquatic organisms such as amphibians, fish, turtles, crayfish, crabs, and other invertebrates. Birds, their eggs, and small terrestrial mammals are also eaten on occasion. They sometimes eat aquatic plants.
Prey is captured with the mouth, and mainly slow, non-game fish species are taken, e.g., suckers. The otter's long whiskers are used to detect organisms in the substrate and the dark water. Prey is eaten immediately after capture, usually in the water, although larger prey is eaten on land.
Did you know?
Otters are capable of swimming in circles, which creates a whirlpool-like motion that brings fish from the bottom of the water up to the top.