About River Otters

River otters are an important part of the ecosystem, where they moderate crustacean populations.

River otters (lontra canadensis) are semi-aquatic, freshwater mammals. They use sounds, posturing and scents to communicate to other otters: males live individually, while females and their pups live together in groups. River otters are an important part of the ecosystem; they regulate crustacean and invertebrate life in their environment. The river otter is a strong swimmer and diver, and also a fast runner.

Physical Characteristics

River otters generally weigh from 12 to 30 pounds and can be 40 to 60 inches in length; male otters are usually larger than female otters. Otters have short legs and long bodies with a muscular tail. The otters' fur is soft and has a thick undercoat and thinner overcoat. The coat is dark brown, with a lighter underbelly. It keeps the animal warm in the water and in its den. The otter also has long whiskers, used to discern environmental characteristics.

Life cycle

River otters breed between March and April, and their pups are born between November and May. Female otters deliver one to six pups, and average about two per season. Female otters raise the pups without the assistance of the male. At 2 months, the pups learn to swim; at 2 to 3 years, sexual maturity is reached. In the wild, river otters live 8 to 9 years; in captivity, they've lived up to 21 years.

Dietary Habits

Otters eat a varied diet of meat and vegetation. Clams, mussels, snails, frogs, and fish make up the bulk their diet. Additionally, otters will feed on birds and plant matter. Otters usually eat smaller food sources (under 3 inches in length) while the remaining in the water, but they take larger food sources ashore for consumption.

Habitat

River otters live in a variety of freshwater and coastal environments, including rivers, marshes, lakes and swamps. The animals thrive in different climates. River otters will inhabit almost anyplace where they find adequate food and water supplies. Otters build and live in small dens, accessing them via an underwater entrance. They pack the interior, dry part of the den with leaves, bark, hair, grass and moss to create a climate-controlled, safe environment.

Adaptations

River otters have webbed feet and a muscular tail, both of which are used for swimming. The otters' nostrils and ears seal to prevent water leakage underwater, while the animal dives for food. The animals have a very high metabolism. They hunt primarily at nighttime, but can be seen during the day: they're known to slide on muddy or snowy hills, into the lake or river they call home.

References

• University of Michigan Museum of Zoology: Lontra canadensis northern river otter
• National Geographic: North American River Otter
• Alaska Department of Fish and Game: River Otter
• Defenders of Wildlife: River Otters