2017-11-16 / Nature

River Otters Make Great Neighbors

By Charles Avenengo

Despite leaving signs of their presence, river otters are seldom seen locally. This otter lives at the Blue Hills Trailside Museum in Milton, Mass. Despite leaving signs of their presence, river otters are seldom seen locally. This otter lives at the Blue Hills Trailside Museum in Milton, Mass. While coyotes have been unwelcome neighbors since moving onto Aquidneck Island, another formidable carnivore, the river otter, has been quietly rubbing shoulders with islanders for decades, possibly even centuries, without creating a stir.

The coyote is originally a denizen of the American West, only arriving in the East in the early 20th century, but otters have always been near or at the top of the food chain in Rhode Island.

Last month, while bird watching along Easton Pond early one morning, I was standing near the spillway at the dam across from the First Beach Newport-Middletown border when, out of the corner of my eye, I saw movement in the water. At first it looked like a fin, which prompted me to investigate. Suddenly, a river otter appeared. It didn’t notice me and I was able to watch it busily fish for a few moments.

This was only my second sighting ever of an otter on the island. The first took place 12 years ago at the Easton Pond access at the Valley Road/Aquidneck Avenue split in Middletown.

It was December and I was conducting a Christmas bird count with former Norman Bird Sanctuary naturalist Kelly Fox. It had been a cold month and much of the pond was frozen. From where we stood, there was open water directly in front of us. The otter suddenly emerged from the water, not even 20 yards away, and then disappeared after spotting us. Otters can stay underwater for up to eight minutes, and despite our efforts to relocate it, the mammal vanished.

Slinking along waterways at a height of about 10 inches, (with serpentine tails extended,) otters are nearly four feet long. The charismatic mammals can weigh up to 30 pounds and are members of the carnivorous weasel family, Mustelidae. This family has 15 species in North America that range in size from the burly wolverine to the nine-inch, nine-pound weasel.

Mustelids are the most diverse family of the world’s carnivores, and their numbers globally include 13 species of otters. All are declining in population, except for the North American river otter, which is roughly estimated at 100,000. But they are difficult to accurately census because of their secretive habits.

Except for the high northern tundra and some western desert areas, river otters range throughout the continent. While they have been known to take the occasional backyard chicken, their diet consists primarily of fish. Therefore, they are found along streams and lake borders, of which Aquidneck Island has plenty.

There are at least 10 waterways that are approximately one mile or longer on the island. The longest is the Maidford River, which stretches nearly four miles from its mouth at Third Beach north to near the Middletown Portsmouth border. Additionally, there are at least 15 ponds and reservoirs that contain enough fish to sustain otters. On average, otters consume between two to three pounds daily.

The otter’s presence is a good sign, because in addition to requiring an abundant amount of fish, they also require clean water. Although the river otter’s population is considered stable, pollution, along with urbanization, has led to some decline in their range.

The only other animal on Aquidneck Island they can be confused with are minks. While they share the same aquatic habitats, otters dwarf minks, which weigh around three pounds and are less than three feet long. Unlike otters, they have white-colored chins.

On that sunny morning last month, after watching the otter hunt for a few moments, I began calling other island naturalists to tell them what I was seeing. I offered to keep an eye on the otter until they could arrive. However, the otter slunk up and over the berm, and disappeared into Easton Pond.

Otters can travel more than 20 miles in a day, and considering that this is only my second sighting despite thousands of times observing nature on the island, it might be a dozen years or more before I see another, if ever.

And, unlike coyotes, that’s the sign of a great neighbor.

Naturalist Charles Avenengo has been chasing Aquidneck Island wildlife for more than 40 years.

Training Offered

Rhode Island shores are a magnet for stranded marine mammals. Mystic Aquarium possesses the federal stranding permit for Rhode Island and is responsible for any marine mammal stranding throughout the state. The aquarium will be offering a basic First Responder class on Friday, Nov. 17 from 6 to 8 p.m. at the Audubon Society of Rhode Island Environmental Education Center in Bristol. For further information about how to get involved, visit the aquarium’s website at mysticaquarium.org.

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