Wild Ideas: Watching the wandering, whimsical water weasel

Last spring I found a pile of fish scales down by the pond in what appeared to be some loose animal scat — the sign of a river otter’s visit. Having never seen a river otter in the wild, I looked forward to perhaps getting a chance to observe this one — that is, before I learned what ramblers these guys are.

I had the great pleasure of watching a pair of sea otters, the river otter’s much larger cousin, off the southeastern coast Alaska, but being able to observe a river otter is actually a pretty rare treat. British author Paul Chanin, in his book “The Natural History of Otters,” writes about the results of his waiting long hours to see wild European otters and only getting brief glimpses: “Five or ten minutes observation for several hundred times as many minutes watching.” It was worth it, though, he writes, just “knowing that the elusive animal really did exist and for the excitement of seeing a wild otter.”

Although fairly common in Virginia, river otters are just as elusive here. Semi-aquatic, they hunt and travel in and along streams and ponds. However, their home range depends on prey abundance, according to the Virginia Fish and Wildlife Service (VaFWIS, vafwis.org), so they “can be from 10 to 100 miles from a stream, covering up to 25 miles in a week, 10-100 square miles in a year.”

Our native river otter, Lontra canadensis lataxina, is commonly known as the northern river otter, Canadian otter, common otter, land otter or fish otter. In the mustelid family, river otters are long and slender like their weasel cousins but have blunter snouts and thicker whiskers, which help in distinguishing them from mink. They are also larger than minks — about 3 to 4 feet long and weighing about 11 to 23 pounds according to “Mammals of the Carolinas, Virginia, and Maryland, with females about 25 percent smaller than males. Having evolved to be semi-aquatic, otters have webbed feet and a thick, tapering tail that serves to thrust the otter forward in the water.

River otters live in dens but do not dig their own. Instead, they use the burrows of other animals, hollow trees, old muskrat houses, or some other protected shelter, according to “Mammals of the Carolinas, Virginia, and Maryland.”

About 80 percent of the river otter’s diet consists of fish. Any species of fish will do, but being pragmatic, they tend to go after the slower species, such as catfish and carp. The otter dives into the water and chases slower fish toward the shore, catching its prey in its mouth and then emerging from the water to eat it. In winter, otters keep a hole or two open in frozen ponds and lakes for fishing.

Although river otters are “beautifully designed as aquatic predators,” writes Chanin, “like most carnivores, they are opportunistic and other types of prey form a variable portion of the total diet.” These include amphibians and turtles, small mammals and birds.

Once in serious decline throughout much of North American, river otters are making a comeback in some areas, including western Virginia, but “are scarce where waters are polluted,” according to VaFWIS. In Virginia, it’s also legal to trap otters west of the Blue Ridge Mountains and, because they generally stick to water courses in their travels, otters are “highly susceptible to overharvesting,” as VaFWIS puts it.

Rappahannock resident Bruce Jones, who has extensively naturalized his property over many years, says he’s had otters visit his pond several times. While they never stuck around for long, he says, a family of five that visited on and off for several weeks starting around Thanksgiving. This gave him a chance to observe and photograph the otters hunting and eating fish, playing, swimming and basking on his dock. Like others who have observed otters, and he says he found them “intriguing” and smart.

“River otters are extremely intelligent animals,” writes Donald Stokes in “Guide to Nature in Winter, with “a high level of curiosity.”

Bruce took photos of his visitors “frolicking, playing and chasing each other,” as he puts it. We often think of otters as more playful than other mammals, but is this accurate?

“The popular view of otters as playful animals is not borne out by observations of animals in the wild,” writes Chanin. Young otters, like most mammal young, play to hone the skills needed in adulthood, and yearlings may be hard to distinguish from adults, so it’s hard to say what Bruce’s visitors were up to. Young otters stay with their moms for about a year, so likely this group was a family on the verge of breaking up.

Bruce photographed one of the otters apparently playing with a rope on the dock, rolling around and rubbing against it. This could have been a yearling at play, or the otter could be rubbing against the rope to groom its fur. Grooming is important to keep the fur fluffy, full of air to protect the otter from cold water. Rather than grooming with their paws, otters often rub up against wood or other objects to fluff up their fur.

Otters’ use of slides they create in snow and mud, as Bruce said he saw his otters do, may also be more pragmatic than playful, according to Stokes: “Sliding in snow is an important adaptation to the restrictions of snow travel, enabling the animal to forage on land in times of winter food scarcity.”

In crossing land, otters use a combination of jumping and sliding, especially when going downhill, Stokes writes. They launch themselves into a slide with their rear feet, leaving sets of paw prints separated by slide marks, which make the tracks easy to distinguish from those of other mammals.

Do otters use slides like kids at water parks, to slide into the water? “A more realistic look has shown that they prefer to walk down slopes into water,” Stokes writes. As Chanin points out, otters may go down slides to get where they’re going, but they “don’t return to the top for another go … as they would do in play.”

Adult otters tend to be solitary outside of reproduction, and what looks like play among adults is often courtship behavior. If successful, this ends with mating, usually in water. Among the great photos and videos of otters at Arkive.org (search on the site for “North American otter”) is a video of river otters courting, and the male appears playful until he pushes the female into water to mate — then it’s all business.

Whatever his otter visitors were up to, Bruce says he hopes they come back. As he reports his grand kids saying when they heard about the otters, “Oh, my gosh, that is so special … something most people only get to read about.” Am I envious? You bet, but I’m still hoping to get a chance to see these marvelous creatures in the wild someday soon.