A playful, social animal, the river otter is not an uncommon sight along the Jersey Shore, especially in winter.
What they are: Otters are mustelids, belonging to a group of mammals that includes weasels, mink and badgers. They’re specially adapted for life in and near lakes, rivers and estuaries, with long, streamlined bodies, a thick, insulated coat of fur and webbed feet on short legs.
The species we see locally, the North American river otter, is light brown to black and can be between 2 and 3.5 feet long, weighing in between 10 and 30 pounds. A long, tapered tail makes up a third of an adult’s length. They have dark eyes and thick, long whiskers that help them sense their surroundings.
A river otter’s diet consists mostly of fish, though they’re opportunistic carnivores, and will also eat crustaceans, mollusks, insects and even small birds and mammals. Fierce ambush hunters, otters can catch and kill fish up to half their own size.
River otters are highly social, and form family groups centered around a female and her young. Adult males often gather in their own close social groups, though adults of both sexes have been known to attach themselves to unrelated otter families as “helpers.”
While they’re far faster and more agile in water, otters are also known for being expert sliders on land. A muddy slope or ice- or snow-covered surface is a perfect substrate, and lets them move much faster than their stubby legs alone can carry them.
Where to find them: River otters used to be abundant across most of the continent, wherever there were permanent bodies of water that offered an adequate food supply. They were extensively trapped for hundreds of years, but habitat loss is the main reason they’re far less common than they used to be.
Otters need plenty of unspoiled waterfront acreage to thrive. Because they don’t dig their own dens in the banks of rivers, streams and brackish waterways, the areas where they live must also support complimentary species like beavers, muskrats and foxes, who do the digging for them. They’re also highly sensitive to pollution from PCBs and mercury.
Development and environmental degradation led to population declines all over the country, but river otters have made a comeback since the mid 1900s thanks to conservation and reintroduction efforts. Today, they’re abundant enough to be given a “species of least concern” designation.
New Jersey’s rivers, reservoirs and coastal estuaries are home to lots of river otters, but because they’re reclusive, many people don’t realize they’re around. From spring to fall, they tend to be nocturnal, but they’re much more active during the day in winter.
Look for them in undeveloped waterfront areas, especially where there’s a steep bank, as opposed to a sloping sandy beach. Studying up on their tracks and scat may help you pinpoint likely otter habitats. I’ve seen otters swimming and playing in Manahawkin’s Mill Creek, and others I know have spotted them in the Metedeconk and Navesink rivers.
Why bother: Otters are highly entertaining creatures. They seem to have a well-developed sense of play, and will swim and dive and chatter with companions and generally look like they’re having a great time.
Because otters are shy and absent form highly populated areas, people are often surprised to learn that they live here at all – and that just makes it more satisfying when one pops up.