River Otters

Otters are often seen near the Nature Centre.  If you see an otter in the Cowichan Estuary, it is most likely a Northern River Otter (Lontra canadensis pacifica).  Even though we are near the sea, we do not have sea otters.  Here’s a chart from the Marine Detective that explains the difference (click the pic to embiggen):

North American river otters (Lontra canadensis pacifica) occur throughout Canada and in many parts of the United States. In Mexico they are found in the delta areas of the Rio Grande and Colorado river. Within their range, river otters are found anywhere there is a permanent food supply and easy access to water. They can live in freshwater and coastal marine habitats, including rivers, lakes, marshes, swamps, and estuaries. River otters disappear from areas with polluted waters.

River otters build dens in the burrows of other mammals, in natural hollows, such as under a log, or in river banks. Dens have underwater entrances and a tunnel leading to a nest chamber that is lined with leaves, grass, moss, bark, and hair.

Males and females do not associate except during the mating season. Births occur from November to May, with a peak in March and April. Females give birth to from 1 to 6 young per litter 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. Sexual maturity is reached at 2 to 3 years of age. River otters normally live up to 9 years in the wild.

River otters live alone or in family groups, typically females and their young. They are known as playful animals, exhibiting behaviors such as mud/snow sliding, burrowing through the snow, and waterplay. Many “play” activities actually serve a purpose. Some are used to strengthen social bonds, to practice hunting techniques, and to scent mark. River otters get their boundless energy from their very high metabolism, which also requires them to eat a great deal during the day.

They are excellent swimmers and divers, able to stay underwater for up to 8 minutes. They are also fast on land, capable of running at up to 29 km/hr.

River otters communicate in a variety of ways. They vocalize with whistles, growls, chuckles, and screams.

River otters eat mainly aquatic organisms such as amphibians, fish, turtles, crayfish, crabs, and other invertebrates. Birds, their eggs, and small terrestrial mammals are also eaten on occasion. They sometimes eat aquatic plants.

River otters are important predators of fish and aquatic invertebrates.

River otters are important members of healthy aquatic ecosystems.