Males and females do not associate except during the mating season. Males often breed with several females, probably those whose home ranges overlap with their own.
Mating System: polygynous
Males and females come together to 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. Births occur from November to May, with a peak in March and April. Females give birth to from 1 to 6 young per litter, with an average of 2 to 3, in a den near the water. They are born with fur, but are otherwise helpless. They open their eyes at one month of age and are weaned at about 3 months old. They begin to leave their natal range at from 6 months to a year old. Sexual maturity is reached at 2 to 3 years of age.
Breeding interval: Breeding occurs once yearly.
Breeding season: Mating occurs in late winter and early spring.
Range number of offspring: 1 to 6.
Average number of offspring: 2-3.
Average gestation period: 2 months.
Average weaning age: 3 months.
Range time to independence: 6 to 12 months.
Range age at sexual or reproductive maturity (female): 2 to 3 years.
Range age at sexual or reproductive maturity (male): 2 to 3 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); fertilization (Internal ); viviparous ; delayed implantation
Average birth mass: 140 g.
Average gestation period: 62 days.
Average number of offspring: 2.5.
Females give birth to, 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.
Parental Investment: altricial ; female parental care