Valley News – The Outside Story: River Otters – The Good Swimmers


Posted: 07/04/2021 21:50:19 PM

Modified: 07/04/2021 21:50:21

One summer day, I was relaxing at the edge of a secluded pond watching mallard ducks feeding when a dark shape shattered the stillness of the water. It was a North American river otter, swimming with its head and back protruding from the surface, smooth body over 2 feet long, tapered tail trailing behind. He dived below the surface without splashing. A few seconds later, his round head emerges at the edge of the pond. We looked at each other.

Making eye contact with a river otter was a first for me, and probably unusual for the animal as well. River otters (Lontra canadensis) tend to be most active from dusk to dawn. This member of the weasel family will travel great distances across its territory, on land and in water, and can explore up to 20 miles of waterways in search of prey. Otters can hunt and swim together in mother and baby family groups or in social groups. They are excellent swimmers, aided by a number of traits that help them maneuver underwater.

“Their bodies are so flexible,” said Margaret Gillespie, a naturalist at Squam Lakes Natural Science Center in New Hampshire. “The way they handle each other is pretty amazing.” Otters swim acrobatically, curling and squeezing through the water. Thanks to their powerful webbed hind legs and strong tails, which also help steer, otters can swim up to 8 miles per hour. For comparison, Olympic swimmer Michael Phelps peaks at 5 miles per hour, while a more average human swimmer can reach 2 miles per hour.

River otters have dense fur that provides insulation and coarse guard hairs that repel water. They are able to close the valves in their noses and ears when they swim and dive, and they have a transparent third eyelid, which functions as swimming goggles. At night, in dark or murky water, however, sight becomes less important than touch, and river otters brush their sensitive whiskers in the water and along the bottom of a pond or river in feeling the movement – maybe a crayfish crawling in the mud between the rocks.

Otters primarily hunt fish and shellfish, but they eat a wide variety of prey including frogs, turtles, birds, and even small mammals. Powerful jaws and sharp teeth creak crayfish shells and fish bones. Because catching fish is difficult for river otters in a strong current, they often hunt in calm waters, including beaver ponds, according to Gillespie. By the late 1800s, New Hampshire’s beaver population had been all but wiped out, largely due to unregulated harvesting during the fur trade and loss of habitat. As a result, the number of otters was also dangerously low. As beaver populations recovered in the mid-1900s and their dams altered water flow, the river otter population also increased. Turtles, amphibians, and muskrats also use beaver ponds and sometimes become prey for otters.

Otters puppies – usually between one and three years old – are born in late winter, furry, toothless and with their eyes closed. River otters often raise their young in abandoned beaver lodges. Baby otters cannot swim for the first few weeks of life, and reluctant teens avoid water until their mother trains them around 2 months of age. In late spring, however, the puppies will feed with their mother and next winter they will be alone.

River otters depend on – and can be indicators of – a healthy and clean ecosystem. Because they are at the top of a long food chain, they can bioaccumulate concentrations of mercury, lead, and PCBs from their prey, which can affect their nervous and endocrine systems, affecting social behavior and pup survival. . They can become malnourished if pollution kills their prey. A stable or growing population of river otters is a good indicator of the prosperity of a watershed: if they are healthy, creatures lower in the food chain are probably doing well.

I felt so lucky to see a river otter that day, even though the experience was brief. Shortly after spotting it, the otter dove to the edge of the pond and ran along the shore through thick brush. This beautiful animal reminded us why we work to conserve wild lands and keep waterways clean and free from pollution.

Rey Katz is a writer who lives in Boston, Massachusetts, and operates a website: reywrites.com. Illustration by Adelaide Murphy Tyrol. The Outside Story is attributed and edited by Northern Woodlands Magazine and sponsored by the Wellborn Ecology Fund of the New Hampshire Charitable Foundation: nhcf.org.


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