North American River Otter

2 otters in snow
photo by Becky_41

Family:  Mustelidae                                                      
Genus SpeciesLontra canadensis

Range:  North American river otters occur throughout Canada and the United States, except southern California, New Mexico, Texas and the Mohave Desert.

Habitat:  North American river otters are found where 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. North American river otters build dens in the burrows of other mammals, in natural hollows, such as under a log or in river banks. Their dens have underwater entrances and a tunnel leading to a nest chamber that is lined with leaves, grass, moss, bark, and hair.

Physical CharacteristicsNorth American River Otters are semi-aquatic mammals, with long, streamlined bodies, thick tapered tails, and short legs. They have wide, rounded heads, small ears and nostrils that can be closed underwater. The dense, soft fur of the North American River Otter is dark brown across the back while the underside is a lighter color.  This thick fur helps to effectively insulate the otter in water. The North American River Otter has completely webbed feet which are great for running and swimming.

Longevity:  North American River Otters have been known to live up to 21 years in captivity and 8-9 years in the wild.

Social Structure:  North American River Otters are often found in groups. A family unit consists of a female and her pups, with or without an adult male. The family usually travels over an area of only a few square miles. Other groups may consist of an adult male and female, a litter of pups that remain together after the family separates, or a group of bachelor males. These groups have no apparent leader, and while they travel together and operate as a social unit, they don’t cooperate in hunting or share what is caught. These groups travel over a wide area; there are no exclusive territories. Fighting among otters is extremely rare.

Diet:  In the wild, they eat mainly aquatic organisms such as amphibians, fish, turtles, crayfish and other invertebrates. In Zoos, they eat raw chicken and fish.

Behavior:  North American River Otters communicate in a variety of ways. They vocalize with whistling sounds, growls, chuckles and screams. They also scent mark using paired scent glands located near the base of their tails or by urinating/defecating on vegetation within their home range. These glands produce a very strong musky odor. They also communicate through posture and other body signals. Although about half of a river otter’s time is spent sleeping, both young and adults are fond of play. They manipulate rocks or sticks, play tag and hide-and-seek, dunk each other, wrestle, and slide on mud or snow.

Reproduction:  Males and females breed in late winter or early spring. Gestation lasts two months, but the young may be born up to a year after mating because these otters employ delayed implantation of the fertilized egg in the uterus. Females give birth to 1-6 young per litter which are nursed and cared for in a den near the water. The young are born with fur and open their eyes at about one month of age. They are weaned at about 3 months old and begin to leave their mother at 6 months old.

Interesting Facts:

·        North American river otters are sometimes taken by bobcats, coyotes, birds of prey, alligators, and other large predators. They mainly escape predation through their agility in the water and on land, their vigilance, and their ability to fiercely defend themselves and their young.

Relationship With Humans North American River Otters are often hunted for their attractive and durable fur. In recent years, more than 50,000 otters have been harvested in North America. Humans also have an effect on river otters through habitat destruction and through the use of harmful pesticides and chemicals.   


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