North American River Otters

Natural History

The North American river otter (Lutra canadensis) is found in almost every state, including Virginia. River otters are extremely social and often frolic in the water with their mates or cubs, slide down hills on their bellies or wrestle with other otters on land. While this behavior is often just play, especially in captivity, it can also serve a purpose. Wrestling can establish dominance between two otters, and muzzle touching shows reassurance or friendly attention. Social grooming is another way to strengthen social bonds between otters.

River otters have many attributes that help them adapt to life in the water. These include a heavy coat of fur, a streamlined body for swimming and special teeth for their carnivorous diet. An otter’s fur is extremely functional for life in the water. It’s incredibly dense with two distinct coats – a long, coarse outer coat (guard hairs) and a short and wooly undercoat that traps air and insulates. This double layer, along with their oil-producing glands, keeps an otter warm, especially in the cold winter months. Otters must clean their fur often to retain its water-repellent qualities. They do this by rolling or rubbing on sand, grass or snow. An otter’s skull is broad and flat with a nose up high for underwater breathing. Their nostrils can close off and their ears can shut with flaps to prevent water from entering their nose and ears. The structure of their eyeball allows them to see very clear underwater by focusing more on objects.

Otters are carnivorous, eating mainly fish, crayfish and insect larvae. They use their twelve sharp, straight-edged incisors for biting off small pieces of meat. An interesting behavioral trait of the river otter is where he eats his prey once he has caught it. They always takes their food out of the water and eat it on shore, even though there may be other predators waiting to steal a bite. The best way to learn about the behavioral and physical adaptations (physical traits or characteristics that help an animal survive and grow in its environment) that help this mammal survive is to watch an otter on land and in the water.

As suited as the North American river otter is to its riparian habitat, these mammals are still a conservation concern. Much of their habitat has been destroyed by filling wetlands and polluting rivers and streams. In the past, they were hunted extensively for their valuable fur and have been killed to prevent the taking of valuable “sport fish” away from fishermen. Virginia currently allows otters to be hunted east of the Blue Ridge Mountains, due to otter populations rebounding. This rebound is partially due to improving water quality in some rivers.

Fun Facts

  • There are 13 species of otters worldwide and are found on every continent except Australia and Antarctica.
  • Otters have the thickest fur of any animal in the world with up to a million hairs per square inch. That’s 10 times what we have on our whole head!
  • River otters can hold their breath underwater for up to 5 minutes.
  • Baby otters are called cubs, pups or kits. They are born in the spring and can live up to 15 years in the wild and 25 years in captivity.
  • Otters love tobogganing in the snow or mud. They slide down on their bellies into the water, jump out, run to the top of the slide, and go again.