North American River Otter



Otters are playful and are known for sliding down mud and snow banks and tunneling under snow. Play helps otter cubs learn to hunt, and keeps otter family bonds tight. They are never far from the water, and with their streamlined bodies, tapered tails, and webbed feet, they are excellent swimmers and divers. They also have special muscles that help them seal their ear canals and noses to keep out water when diving for food and fun. Their dense fur acts like a wetsuit to keep them warm.

Adult North American river otters are usually solitary. They live in one or more burrows beside the water and are usually more active during dusk and at night. They can run up to 18 miles an hour and are even known to get down on its belly to toboggan across snow! In the wild, this agility on land and water helps them escape predators such as bobcats, coyotes, and birds of prey.


Otters eat fish, frogs, crabs, crayfish, mollusks, and small mammals. Their dense whiskers aid in detecting vibrations and changes in water current, which can help them locate prey.

Life Cycle

Otters give birth in the late winter or spring to a litter of up to six cubs. The tiny newborns weigh about 5 ounces at birth, and don’t open their eyes until four weeks of age. They leave their den and start to swim by two months, and leave their mothers’ side after about a year. By three years of age, they are fully mature. River otters can live around 20 years in zoos.

Population Status & Threats

The North American river otter population had suffered serious declines by the early twentieth century because of hunting and water pollution. When the U.S. began passing laws to clean up the waterways, otters rebounded throughout parts of their former range. Hunting legislation and efforts to reintroduce populations to parts of their wild habitat also helped boost their numbers. Even though poor water quality still affects some areas, the river otter has recovered sufficiently so that it is now considered a species of least concern.

WCS Conservation Efforts

Scientists with the WCS-Adirondack Program are studying the effects of water pollution on another iconic North American animal, the loon. The researchers have found that mercury emissions from power plants degrade the health and reproductive success of these birds in the Northeast. WCS is urging the Environmental Protection Agency to pass effective national regulations for mercury emissions to help protect North American wildlife.