Long Island’s River otter population is on the rise

06/18/2019 6:00 AM |

Photo caption: A river otter was spotted at Marion Lake in East Marion.  (Carolyn Bunn photo)

The North American river otter is making a comeback on Long Island, a place where otters were thought to have vanished not that long ago.

Mike Bottini, a wildlife biologist for the Long Island Nature Organization, has been studying otters for years and said that, while otters appeared to be making a comeback on Long Island in the past, it’s now more conclusive based on the results of studies he undertook in 2008 and 2018.

“I have enough information to say it looks like they have expanded their range considerably on Long Island,” he said in an interview last Thursday.

Factors including unregulated trapping, water pollution and habitat loss are believed to be responsible for the otter’s disappearance from places like Long Island by 1800. But conservation laws enacted in the twentieth century — such as a ban on otter trapping from 1936 to 1945 — enabled what was left of otter populations to expand and recolonize.

Otters are difficult to locate in the wild, so the best way to measure their presence is by the number of so-called otter latrines in a particular location, Mr. Bottini said.

Otter latrines, he explained, are sites where otters leave their scent in the form of scat and small areas cleared of leaf litter.

In 2008, Mr. Bottini and a team of volunteers surveyed 143 areas and found 22 otter latrine sites. Compare that to 2018, when a survey of 168 areas across Long Island revealed 77 latrine sites.

The 2008 study showed a gap of about 40 miles on the North Shore where there were no signs of otters were found. This area stretched from the North Shore of Suffolk and Nassau counties all the way to Greenport and Shelter Island, he said.

By 2018, however, there were signs of otters on the North Shore. Scientists have also learned about the presence of otters based on some cases where they were hit by cars. In one case, Mr. Bottini said, an otter was hit by a car on Route 111 in Manorville, just south of the 7-Eleven.

The people who found it said it was on the west side of the road, and it looked like it was headed south.

“So I get on Google Earth and I wonder, ‘Where the heck did it come from?’ ” Mr. Bottini said.

“It turns out there’s a tributary of the Peconic River that I never knew about, that goes under the Long Island Expressway and ends in the back of the that place with all the wooden sculptures, not too far from Starbucks. And then I’m thinking, ‘Where’s the next wetland that it would have been heading to?’ — because I’ve driven that road thousands of times.” It turned out there is a red maple swamp and a pond that Mr. Bottini said he never noticed before.

An otter that was found dead on Route 58 in Riverhead in April 2018 appeared to be headed toward five little freshwater ponds on the north side of the road, which Mr. Bottini also hadn’t known about previously. There was “tons of otter scat” on two of the ponds, he said.

But where did the otter come from?

“The only place it could have come from is the Peconic River, because the Riverhead ponds are too small an area for it to live year round,” Mr. Bottini said.

He said he then found a tributary south of Route 58 that goes right into the Peconic River. The ponds on the north side of Route 58 were recently cleared for a shopping center, and Mr. Bottini believes this was a wetlands violations.

The Arshamomaque Preserve in the unincorporated part of Greenport is the No. 1 one spot in the region for otter sightings, Mr. Bottini said.

Caption: A river otter spotted at Marion Lake in East Marion last May.  (Carolyn Bunn photo)

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