You Otter Know: River Otters in Winter

North American River Otter on an icy river edge in winter © Joseph Cavanaugh
North American River Otter © Joseph Cavanaugh

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This article was featured in the Winter 2020 issue of Explore, our quarterly magazine for members.

ZIP, ZIP, ZIP. A group of otters wizzes down a muddy slide on their bellies, splashes into the water, then turns and immediately scrambles up the embankment for another go.

North American River Otters are the charismatic clowns (and the largest members) of the weasel family, well-known for their playful antics and excellent swimming abilities. With a long, muscular body and short legs ending in webbed feet, otters are streamlined for peak efficiency in the water, making them well-suited for a diet of mostly fish, crayfish, frogs, turtles, and other aquatic invertebrates.

But what happens when the water turns frigid and lakes freeze over?

Perhaps surprisingly, otters don’t really slow down. A double layer of fur—dense underfur for warmth plus a waterproof outer layer—and a second, clear eyelid allow otters to see and swim gracefully in even the iciest of waters. If there are air pockets under the ice, otters can stay underwater for long periods of time without having to surface. They may even dig up hibernating turtles or frogs from the bottom of the pond.

Where there are beavers, you may also find otters. Beavers make for great neighbors! Their impoundments (ponds and wetlands formed by beaver dams) provide a good supply of fish for otters without any additional competition for resources, since beavers are herbivores. Plus, beavers often maintain holes in the ice that otters can use as access points, and their lodges—both abandoned and inhabited—can be used as den sites by the otters.

In higher elevations, deep freezing of waters can force otters to leave the area for lower, warmer elevations, but if all waters become deeply frozen they are capable of traveling long distances over land in search of food.

Not only are otters expert winter survivalists, they even seem to enjoy the coldest season, continuing to frolic, wrestle, and play and using snow and mudslides not just for easy locomotion but also for fun.

Why not take a page out of their playbook and get outdoors this winter for some fun in the snow?