North American River Otter
Scientific & Common Names
Kingdom - Animalia
Phylum - Chordata
Class - Mammalia
Order - Carnivora
Family - Mustelidae
Genus - Lontra
Species - L. canadensis
Common Names - North American River Otter, River Otter, Common Otter, Northern Otter
With webbed feet, powerful tails, and water-repellant fur, river otters are perfectly adapted to spend hours in the water. Adult river otters can weigh between 10 and 25 pounds, and they are typically between 35 to 53 inches in length. Their tails make up 30 or 40 percent of their full body length. Otters have broad, rounded heads, small black eyes, tiny ears, and plentiful whiskers on their faces. They are usually dark brown or reddish brown. And they have short legs that enable them to run well on land.
Male and female river otters mate in late winter or early spring. However, implantation of the fertilized eggs may not occur for up to a year after mating. When the egg finally does implant in the uterine wall, the pregnancy takes about 62 days to complete. Female otters will retreat to their dens to give birth to up to six babies. After about 2 months, the mother will shove the young into the water for their first swimming lesson. The otters will be sexually mature around 2 or 3 years old, although the babies will leave their mothers when they are about 6 to 12 months of age.
River otters are members of the weasel family, and they are mostly nocturnal. They hunt after dark, and they will eat any animal that they find in the water. Otters consume amphibians, insects, crayfish, fish, and turtles. River otters will only live in places with adequate vegetation. They live in burrows in the bank of a body of water, and they frequently use old beaver dens for their homes. Male otters are typically solitary animals, but sometimes they live in "bachelor" groups of all male otters. Females usually live in groups of 3 to 5 consisting of a mother otter and her offspring. Otters can hold their breath for up to 8 minutes under the water, and their nostrils and ears close when they are submerged.
Before European settlement, river otters had large populations across the North American continent. In the 1800s, trapping and the fur trade reduced their numbers. Additionally, as industrialization polluted water and water management re-routed rivers, otter numbers suffered further losses. By the 1970s, resource management began efforts to reduce pollution and improve habitats. Over the last 30 years, management officials have released over 4,000 otters in 21 states.
Current numbers of river otters are stable. They live near wetlands, rivers, streams, lakes, and marine coasts in all states of the United States. Currently, river otters are being reintroduced to the Rocky Mountain region.