But what exactly are river otters? Well for starters, they’re members of the weasel family, Mustelidae. Notable relatives include weasels, mink, ferrets, badgers, martins, and wolverines. Like mink, though, river otters are aquatic mammals, spending most of their time in the water.
River otters have elongated bodies with flattened heads and streamlined profiles. They weigh 11 to 30 pounds and range from 26 to 42 inches. Their tails can be about a third of their body length and, along with their webbed feet, help their agility when propelling through the water.
Otters’ thick dense coats insulate the skin from the water as well as cold temperatures. Their fur’s waterproofness comes from glands that produce oils the animals distribute throughout their bodies by frequent grooming.
As carnivores, otters dine on fish, crayfish, mussels, frogs, turtles, and snails. Their long whiskers help them locate prey in dark or turbid waters, and their sharp teeth and claws make for easy meals. They will occasionally eat waterfowl, muskrats, beavers, and cottontails, the latter showing they’re capable predators on land as well as in the water.
River otters den in or near the water, typically along the banks of rivers or lakes and sometimes in abandoned beaver or muskrat lodges. Polygamous, otters mate with several partners in their lifetimes. Females give birth to pups in their dens with litters from one to six, although two to three is more common, and will stay with their young in family groups for seven to eight months. The males do not stay with their families but will form social groups with other males that hunt and travel together.
Like most mammals, river otters are active year-round, although they tend to be more nocturnal during spring through fall and more active during the day in winter. On land they walk, run, or bound, but they even slide, which can be more efficient when travelling across snow or ice or down slopes.
When spotted, river otters can be fun to watch in social settings because they often appear to be playful. They like to chase each other on land and in the water while indulging in a slide when an embankment is nearby. These activities may
look like simple play, but they improve hunting skills and strengthen social bonds.
Whenever a species like the river otter recovers, it adds to the biodiversity of the land. After all, each species is unique and has a niche in the ecosystem. Next time you’re near a river, marsh, or lake, scan the area. You might be rewarded with an otter sighting of your own.