The Mischevious World of Otters

Otters just wanna have fun! These wild little carnivores always seem to be clowning around, romping in and out of the water, sometimes crunching on their favorite meal — crayfish. They clamber up and down the banks of our rivers exploring, hunting and hiding to, seemingly, create mischief.

Although native to Colorado, the otter population was trapped out in the early 1900s, decimated from the fur trade and habitat destruction. The population, at the time, was sparse to begin with. Finally, in 1976, the Colorado Division of Wildlife, now the Colorado Parks and Wildlife (CPAW), began a reintroduction and introduced more than 100 river otters to various Colorado rivers between 1976 and 1991.

-991“Most of the reintroductions focused on West Slope rivers in the upper Colorado, Gunnison, and the Green and Yampa Rivers, with partners in Utah,” explains Eric Odell, species conservation program manager with CPAW. “And, since then, we’ve watched the population expand. Now we have otter populations in most of the major drainages in western Colorado with, from time to time, sightings in eastern Colorado.

“So it’s a big conservation success to have re-established this species, once native to the state, then extricated — meaning it was no longer in the state. Now we’ve got healthy populations.”

Otters are bigger than other aquatic mammals, ranging about three to four feet in length, the tail making up almost a third of that body length. These little carnivores can remain underwater for nearly four minutes, closing their ears and nostrils to keep water out. They can swim at speeds up to seven miles per hour, dive to depths nearing 22 yards and travel up to 440 yards while under water. And, despite the fact that they are most comfortable in water, otters do sometimes travel on land, using a gait of running and sliding. In fact, otter slides can be spotted in sand, grass and mud as well as on ice and snow, with slides ranging from roughly eight to 12 inches wide and as long as 25 feet. Their tracks show the webbing between the toes and the indentations from their nails; their back paws are slightly larger than the front and sometimes there is a thick, long drag mark behind the tracks made by the tail.

And, although these mammals live fairly solitary lives, defending their territory from other members of the same sex and loose groups are common. They seem to tolerate one another, sharing overlapping turfs and may even hunt cooperatively. Sometimes males form “bachelor pods,” hanging out together to party where they seem to find joy in piling up vegetation on which to defecate.

According to preeminent otter expert, Hans Kruuk, honorary professor at Scotland’s University of Aberdeen, excretions are a very big deal for otters, as latrines are communication stations where animals frequently stop by to leave small symbolic fecal deposits, make scent secretions using the glands in their hind feet and investigate what else has been left behind. It’s sort of a record of who was around and what they had for lunch. And, according to Kruuk, no carnivore produces scent-mark feces more frequently than an otter.

Otters must swim in cold water in order to eat, explains Kruuk. And they must eat a lot, most OTTER_2consuming 12 to 15 percent of their body weight each day — far more than most mammals of similar size. To stay warm without blubber, they fuel the body with calorie-dense food. Essentially, an otter’s life is like a catch-22 and they must hunt to stay warm and stay warm to hunt. And otters are always hunting; they’re smart enough to target particular species when they know those fish are sleeping. However, although they prefer fish, they’ll eat almost any meat, including frogs, crayfish, shellfish, insects, small mammals and birds.

Otter pups are born in late March or early April. Yet, shortly after the females give birth, the otters begin breeding again. The embryos then undergo delayed implantation, and wait around for nine months before beginning a 60-day gestation period. And, when the time is right, the mama otter leaves the active river where she can den in, say, a hollow log or abandoned burrow until the two to four pups are born. These little guys open their eyes at three to four weeks and most will be ready for a swim within the month. Even though they are fully weaned by about ten weeks, the pups usually stay with their family throughout the fall and sometimes for the entire winter.

In the past few years, otter slides have been found at the ponds in Gypsum and local kayakers and rafters have spotted them playing on the Upper Colorado and Eagle Rivers.

OTTER_3So, if you’re around or on the river this summertime, keep your eyes open! Remember, these critters are often confused with beavers, muskrats and mink — especially when they are swimming. Look closely and remember that the otter is bigger and has a thicker, longer tail than the other animals.

The truth is, it really doesn’t matter what animal you might be lucky enough see on any outdoor adventure. A sighting of any from a deer to a bear to a moose to an otter is magical. It’s just part of the joy of living in Colorado and this valley.