North American River Otter : Lifestyle
Band of otters
North American river otters are more sociable than Eurasian otters, with family groups typically consisting of a mother and her offspring, but sometimes with unrelated helpers included. There are sometimes groups of unrelated males travelling and hunting together. This is especially common where otters have adapted to coastal environments. During the breeding season groups often break up.
Lontra canadensis has a special ability to delay implantation of fertilised eggs for 8 to 10 months after mating, so it may be up to a year before they actually give birth. This is unique among otters, and may be done to make sure that the birth takes place at the best possible time - usually in spring. Litter sizes are between 1 and 5, though 1-3 is most common.
Counting the years
These otters can live up to 25 years in captivity. In the wild 8 or 9 years is most common, although there is a reliable record of a 13 year old otter grandmother here.
River otters have overlapping ranges of a few miles, and the actual size varies depending on the habitat and how much prey there is.