From the December 2013 Conservationist
Photo: Eric Dresser
The River Otter
Surprising little clown
By John Razzano
Photos by Eric Dresser unless otherwise noted
Known for its playful nature and comic antics, the North American river otter (Lontra canadensis) is one of the most entertaining wild animals to call New York State home. This semi-aquatic mammal is a member of the weasel family (Mustelids), and people lucky enough to spot one in the wild are often captivated by its clown-like actions.
Fish make up the bulk of the otter's diet.
Otters have been around for a long time. Paleontologists unearthed fossils of otter-like animals that inhabited the earth 30 million years ago. From these ancestors, thirteen known distinct species have evolved worldwide. The largest is the sea otter, weighing up to 100 pounds; the smallest is the Asian short-clawed otter, weighing less than 10 pounds. New York's river otters average between 10 and 30 pounds, and measure three to four feet long.
Intelligent and appealingly gregarious, river otters are bundles of energy that make their homes alongside streams, wetlands, bogs, lakes and, of course, rivers. They eat primarily fish, but are opportunistic feeders and so will also eat amphibians, crustaceans, turtles, and even small mammals and birds. Remnants from these meals, including bits of shells or scales, are sometimes the only evidence that indicate otters are in the area.
Otters are what wildlife biologists call "apex predators," meaning they're at the top of the food chain. They have few enemies in the wild. This may seem unusual when you consider that otters aren't very big as far as top predators go. But what they lack in size, they more than make up for in feistiness against attackers. However, otters do occasionally fall prey to bobcats, eagles, coyotes and domestic dogs, usually while traveling over land.
Having long, muscular bodies, thick, tapered tails and webbed feet, otters are swift and graceful swimmers. Their bodies are so flexible that they can bend forward or backward into a circle, touching nose to tail from either direction. Their dense, lustrous coats range from light-brown to black above, and pale grayish-brown to silver underneath.
Otters' eyes, ears and noses are set close to the top of their broad, flat heads. This allows them to see, hear and smell while largely submerged, skimming the water's surface in stealth mode. Otters have keen eyesight, even underwater, and they can tightly close their small ears and nostrils as they dive for food. Long stiff whiskers, called vibrissae, are used for sensing prey in the mud or finding the underwater opening to a burrow in murky water.
Active year-round, otters can be spotted playing or foraging during the day, especially in winter. They will pop through openings on the margins of ice-covered water bodies to breathe, or will catch a breath from pockets of air under the ice. Otters have been known to remain underwater for as long as eight minutes while diving in search of fish. Their sharp, formidable teeth are designed to grip and hold their catch. If an otter feels threatened, it won't hesitate to inflict a vicious bite on any creature that's hungry or foolish enough to harass it.
Though much more at home in the water, otters can actually bound along quite well on land. One way they get around is by sliding on their bellies. If the ground is fairly flat, they alternate running and sliding. Otherwise, a fast belly slide down a muddy or snowy bank into the water is a favorite otter pastime.
River otters often travel together as
a family group.
Family groups of otters will occasionally be seen sliding and splashing with apparent abandon. It may appear that they're just having a good time, but, as with most animal behavior, this is fun with a purpose. Sliding teaches important survival skills for escaping predators. Otters can be quite vocal, making sounds described as chuffing as well as squeaks, squeals and grunts.
Otters "borrow" the unused burrows of other critters rather than digging their own. Abandoned beaver lodges and muskrat dens, as well as hollow logs and under large roots all make good otter homes.
Mating occurs from late winter through spring. Females have the ability to delay fertilization for several months after mating, which means that from the time otters mate until the female gives birth can be as little as 60 days or as long as a year. In the spring, pregnant females retreat to their dens to give birth. Though litters of five are not uncommon, otters typically have one to three furry, blind, toothless pups.
Pups are weaned after 9 or 10 weeks, at which time they're ready for their first swimming lesson. Yes, surprisingly, these masters of the water must be taught to swim! Using her mouth, a mother otter will pick up her pups by the scruff of their necks and drop or drag them into the water to give them a crash course in swimming. Females may also use the ride-and-dive technique, where she gives her youngster a ride on her back and then dives, leaving her pup to fend briefly for itself until it gets used to treading water. It only takes a few lessons before the pups are swimming with nearly as much confidence as their parents.
Females bring food to their young for up to 40 weeks and stay with them for as long as a year before the yearlings strike out on their own. Males take no part in raising the young. An otter that survives mishaps and diseases will usually live an average of eight or nine years in the wild.
Sitting atop the food chain, otters accumulate pollutants like PCBs, DDT and heavy metals in their bodies. Biologists are concerned that pollutants shorten otters' lives or hamper their ability to reproduce. Because otters seem sensitive to pollution, some biologists consider them an "indicator species," either sounding the alarm that a former habitat is seriously degraded when they disappear, or indicating that conditions have significantly improved when they reappear.
An otter's flat head helps it course
through the water with great speed.
Photo: Susan Shafer
Through the years, otter populations have had their ups and downs. When European colonists first arrived in what is now New York State, the surrounding land teemed with dozens of fur-bearing mammals (including otter) which were immediately identified as potential sources of wealth. Beaver were the first to suffer overharvesting as countless pelts were shipped overseas to satisfy the European fad of beaver felt hats. Otter were also exploited for their pelts and expanding settlements gobbled up their habitat as wetlands were drained and forests cleared. By the early 1900s, otter populations were largely limited to remote wilderness areas like the Adirondack and Catskill mountains. Fortunately, these populations, as well as additional populations in the Hudson and St. Lawrence River valleys, have remained healthy, even to today.
In 1995, business, government and non-profit groups came together to conduct the New York River Otter Project to restore otters to Central and Western New York where water pollution and loss of habitat drove them out. (See February, 2001 Conservationist.) Grade school children, a big utility company, environmentalists and trappers raised more than $300,000 to capture otters from the Adirondacks and Catskills and then care for them before they were released. During the five years the restoration project was conducted, 279 otters were successfully released throughout the region. The positive results of the project generated inquiries from European countries also interested in otter restoration.
DEC Senior Wildlife Biologist Andy MacDuff is conducting a study to determine the status of otter populations in the Mohawk River Valley, and to develop survey methods to monitor otters in Central and Western New York where they were reintroduced. The study consists of intense "sign surveys," whereby he repeatedly visits certain sites to look for otter tracks, scat, snow-slide furrows, etc. He'll compare these results to data he's collected in the St. Lawrence River Valley, where otter are known to thrive. If his results verify that the otter populations in the Mohawk River Valley are secure, DEC may reopen the otter trapping season there, which was closed more than a decade ago.
In a similar vein, SUNY College of Environmental Science and Forestry graduate student Elaina Burns has been studying river otter in the Finger Lakes region. Elaina's work centers on estimating otter populations in this area using non-invasive genetic sampling gathered from otter scat as well as monitoring otter activity at latrine sites using trail cameras. Both Andy's and Elaina's work will help DEC develop a larger study to fully assess the outcome of the reintroduction effort of the late 1990s.
New York is fortunate to have healthy otter populations in a number of areas across the state. In fact, small numbers of otters have recently been seen on congested Long Island, a hopeful sign that otter populations are expanding to other parts of the state.
I've never seen an otter in the wild, but I hope to. And when I do, I'll remember what Andy said to me: "If you're lucky enough to see otters in the wild, just sit back and enjoy the show."
John Razzano is a contributing editor to Conservationist.