River otters typically give birth from March thru April. Litter size is usually 1 to 6 young per litter weighing about 4 to 6 ounces are born with fur, but are otherwise helpless. They stay in family groups during the summer and early fall. Pups grow rapidly and emerge from the den at about 2 months old. They remain as a family unit for seven to eight months or until the birth of a new litter.