Rivers otters are mostly solitary (live alone), except for females with their young.

Otters come together during the mating season in late winter or early spring.

Females give birth to 1 to 6 young per litter, with an average of 2 to 3.

Otters are born with fur, but are otherwise helpless.

Females give birth, 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. Adult females care for their juvenile offspring, who disperse by the time the otters give birth again. River otter become mature at 2 to 3 years old.