River Otter               

Introduction

River otters are adaptable animals inhabiting a variety of aquatic habitats including ponds, rivers, and saltmarshes. They are related to weasels, minks, and skunks. They are semi-aquatic, large ( 35-50 inches) mammals with a short, blunt snout and conspicuous whiskers used to locate food in turbid water. River otters have small eyes and ears, thick necks, legs that are short and stout, and webbed toes. The tail is long and thick and tapers at the tip, and the ears and nose are protected by flaps of tissue that close when the animal is under water. They mark their territory using scent from their feces, urine, and musk. They also communicate by making sounds, like a bird chirping, a grunting sound when playing or grooming, and a high pitched scream when fighting or mating. When they get surprised or frightened, they may snort.

As graceful in the water as they are on land, these strong, energetic members of the weasel family seem to delight in making a game of everything. They'll chase after a pebble, a shell, or each other for hours, and their favorite activity is body-sledding down a slippery slope and landing with a belly-flop in the water. They are excellent swimmers and can stay underwater for up to 4 minutes. They’ve actually been known to dive to depths of more than 40 feet. Often found in the same territory with beavers, they've been known to swim up and mischievously tweak the flat tails of their more businesslike neighbors. River otters may travel fifteen miles a day following rivers and streams in search of food. They live about 15 years in the wild.

Food Habits

River otters establish home ranges that vary in size depending on the animal’s age and gender and on food availability. They are most active from dusk to dawn, but diurnal activity it is not uncommon. River otters are carnivores, feeding mainly on fish, such as suckers, minnows, sunfish, bass, and minnows. They also eat crayfish, frogs, and miscellaneous animals. They like to forage near shorelines, overhanging banks, and areas where fish are found. They will also eat birds and vegetation.

Family Life

River otters, as in other Mustelids, have delayed implantation. The fertilized eggs float around in the uterus for about 9 months before implantation occurs, rather than implanting on the uterine wall shortly after fertilization. Gestation lasts about 60 days, and 2-4 young, called kits, are born almost 1 year after conception. The female otter usually gives birth to two to four kits in a den located in a hollow tree or some other type of shelter. Young otters are born about 4.5 inches long, furry, with their eyes closed for about a month. Pups are weaned at 8-10 weeks and then they learn to swim. Female otters teach their young swimming and foraging skills until they can look after themselves, usually by 6 months. However, kits usually stay with their mother until they are 1 year old. Adult male otters do not participate in caring for the young.

Otters are also devoted parents, unusual among mammals in that when the young are weaned and old enough to leave their riverbank den, the male often joins the female to help in raising his offspring. Young otters do not take willingly to water at first, but coaxed by their parents, these fresh-water clowns quickly learn the pleasures of swimming and diving. With their streamlined bodies, webbed feet, and rudder-like tails, the adept aquanauts can reach speeds of seven miles per hour underwater, and depths of thirty-five feet or more.

Winter Habits

In winter, otters stay near water but may travel overland to catch rodents. They travel through snow by sliding and bounding. They keep a hole or two open for fishing in frozen lakes. They use dens for protection in winter, such as a groundhog burrow, which may be up to 500 feet from water.

Threats

River otters have been heavily harvested for their fur throughout much of their historic range. Some states still have otter trapping seasons. Currently populations of river otters are threatened by pollution (including pesticide poisoning), acid rain, habitat loss, and illegal hunting.

Benefits

Problems and Solutions