River otters, landing on the North Shore after swimming in from the Bronx, Westchester and Connecticut, are only gradually expanding their range on Long Island — and cars could be the reason, experts say.
The problem, explained Mike Bottini, a wildlife biologist with the nonprofit Seatuck Environmental Association, who tracks otters killed on the road to learn where these shy creatures are dispersing, is that so many of the Island’s dams are too high, blocking them from ponds or wetlands on the far side.
So the river otters, especially youngsters who head out on their own after about a year, must venture out on the roads — with all too often fatal results because so much of Long Island's open space lies between highly developed areas.
After an otter recently died on an Eastport road, Bottini, working with the Town of Brookhaven, built a 4½-foot stairway out of about a dozen concrete blocks, each about 8 inches high, at a dam on the hamlet's Little Seatuck Creek, which flows into the Great South Bay.
Two cameras were set up to see if any otters — or other water-lovers, such as raccoons and muskrats, also use the new stairs.
After about three centuries of trapping that started in the 1600s, New York State had just one group of river otters left in the Adirondacks, Bottini said.
A total of 279 river otters were caught and released in western New York from 1995 to 2000, the state Department of Environmental Conservation says. Long Island was not seen as a place they could thrive.
Yet now river otters have been leaving their tracks and scent from Glen Cove to Orient Point on the North Shore, by the Connetquot and Carmans rivers on the South Shore, and out East, by the Peconic River — and in Southold, and East Hampton though not Montauk or Amagansett, Bottini said.
"We probably have several dozen" on Long Island, he said. Counting them is tough. Though highly social, river otters are elusive, and lack distinctive markings, which can leave biologists wondering if the trail camera captured a new otter — or a regular.
If the otters use the new stairs, more may follow, Bottini said, noting ramps are another possibility.
Said Amanda Bailey, a DEC wildlife biologist: "This is kind of a cool first step, we'll have to see how it works."