Northern River Otter

Lontra (the Italian word for otter)
(referring to the origin of the first described species)

By Tom Dickson

This story is featured in Montana Outdoors March-April 2011 issue

After making camp along the Yellowstone River, I walked upstream 100 yards to fish while my wife, Lisa, settled on a boulder to read a magazine. After casting for an hour with little luck, I spotted a family of otters in the river and sat down to watch. They were hunting a riffle, porpoising along the shallow water in search of fish and crawfish. Then they swam downstream toward Lisa. She told me she watched the otters swim around a deep pool then was startled to see a massive trout rise to the surface, apparently fleeing the predators, before disappearing. Otters generally eat whitefish and suckers, which are slower and easier to catch, but they will take a trout if given the chance.
Later that evening I hooked what I suspected was a big brown, but the trout broke off before I could get a good look at it. I wonder if, like me, those otters ever dream of the big one that got away.

There’s no mistaking an otter for another species. The streamlined mammal has a long, cylindrical body, broad head, and thick neck. Adults weigh roughly 20 pounds and stretch 3 to 4 feet from nose to the tip of their thick, muscular tail. Otters have stubby legs, webbed feet, and small eyes and ears. Long, thick whiskers help them detect prey underwater, where these members of the weasel family spend most of their time. Otters have sharp canine teeth for capturing fish and large molars for crushing mussel shells.

The otter’s thick, short, and lustrous, the otter’s fur is dark brown except where it lightens on the throat and chest. The extremely dense underfur has “cuticular scales” that allow the hairs to interlock and trap air, creating insulation against cold water. Because their fur must stay clean to insulate well, otters constantly roll on sandy areas, grassy banks, and snowfields to remove dirt—behavior often mistaken for play.

Otters do play—pups especially—sometimes chasing each other for hours. They are fast, agile swimmers, able to dive 45 feet or more and stay underwater for up to four minutes. Otters travel on land by bounding along on their short, muscular legs. On snow, they alternately slide and run.
In summer, otters are most active at night. In winter, they become diurnal and are much easier to spot and photograph.

Otters eat fish, crawfish, dragonfly and stonefly nymphs, and frogs. Strong enough to fend off coyotes and able to escape mountain lions by sliding into streams, they have no natural predators.

Otters once ranged throughout North America as far south as Mexico. Unregulated trapping in the early 1900s greatly reduced pop­ulations, as did water pollution and the loss of streamside vegetation. By the mid-20th century, otters were extirpated (made locally extinct) in much of their original range. Since the 1970s the animals have been successfully reintroduced in many states. In Montana, otters live mainly in the state’s western half and along the Yellowstone River drainage east to Miles City.

Look for otters along narrow streams containing log jams, beaver ponds, and backwater marshes bordered by willows and other shrubs. When smaller streams freeze in winter, otters move sometimes dozens of miles to larger, open rivers. Otters sleep in dens such as hollow logs, openings under streambanks, or burrows made by muskrats.

Brian Giddings, coordinator of the FWP Furbearer Program, says Montana’s river otter population is healthy enough for the state to allow regulated trapping. The limit is two otters per trapper per season. Roughly 70 to 100 otters are trapped each year, Giddings says.Bear bullet

Tom Dickson is editor of Montana Outdoors.