Mike Scheibel immediately knew he had an active nest, so he hopped out of his pickup truck, pulled out a Swarovski spotting scope and watched the ospreys in action.One osprey could be seen flying around the nest of piled-high sticks, and the other was barely visible—her brown-and-white head sticking up just above the nest out in the marshes of the Mashomack Preserve on Shelter Island.
Mr. Scheibel, the natural resources manager at the preserve
for The Nature Conservancy, which owns it, earlier this month recorded how many nests were active there. An active nest means that two birds have set up a home on a pole or dead tree and are incubating their eggs.
At each nest, Mr. Scheibel went down his list, marking off in pencil whether there were ospreys visible in the nest or not, noting any differences that he noticed from the year before. The information would later be included in a report and sent to the New York State Department of Environmental Conservation.
“It’s pretty darned easy to see if the nests are active or not,” Mr. Scheibel said, explaining that the Conservancy checks the numbers each year. “Once you’ve looked at thousands of these things, you get a feel for it.”
He said on Shelter Island alone there were close to 42 nests, 15 of those in the preserve, in 2013. He also tracks the birds at Robins Island and Gardiners Island, which are privately owned. Those islands, combined with Shelter Island, had a total of about 75 nests in 2013.
The surveys offer some good news: The number of ospreys has been steadily increasing in recent years, a significant improvement over what had been dismal numbers in the mid-20th century.
Historically, eastern Long Island was home to the largest number of breeding ospreys in the world. However, according to the DEC, the osprey population declined from approximately 1,000 active nests between New York City and Boston in the 1940s to an estimated 150 nests by 1969.
It was the increased use of the pesticide DDT during the 1940s and 1950s that had nearly decimated the osprey population, as well as those of the bald eagle and peregrine falcon, by the late 1960s. According to Aaron Virgin, the vice president of the Group for the East End, a Bridgehampton-based environmental organization, the chemical was found to thin the ospreys’ eggshells, stopping the young from incubating correctly, as well as accumulating in the fatty tissues of animals and humans.
The U.S. Environmental Protection Agency banned the use of DDT pesticide across the nation in 1972 after marine biologist Rachel Carson, in 1962, published her book “Silent Spring,” which detailed the harmful effects of DDT, and conservationists like Dennis Puleston, Art Cooley, Paul Stoutenburgh, Alan Poole and Paul Spitzer also advocated against DDT.
Since then, environmental groups have been trying to help the osprey population rebound by providing poles and platforms for them to nest on, keeping them away from predators like raccoons, and high enough to scout for fish. They also monitor the ospreys each year.
Osprey are a “keystone” species, at the top of the food chain, and indicate the health of the environment, particularly marine ecosystems, through their health and activity.
According to Mr. Virgin, the Group for the East End has been watching the birds closely for decades, and determined that decreased water quality can hurt the birds. “Red and brown tides affect the bottom of the food chain, like phytoplankton,” he said. “If the osprey’s food supply is gone or dwindles, they’re the first ones to disappear.”
Mike Bottini, a naturalist and wildlife biologist who worked for the then-Group for the South Fork in the 1980s, said it is difficult to see what’s going on in the water, so ospreys serve as a good warning sign. “Monitoring nests and hatchlings fledged over time is a good thing to reveal any potential problems or changes in the marine ecosystem because they’re fish eaters,” said Mr. Bottini, who is also an outdoors columnist for The Press.
According to the Group’s numbers and what others on the East End have gathered, there are currently about 250 breeding sites in all five East End towns, up from about 200 to 220 in recent years, and reflecting an increase of about 12 to 15 each year. Their most recent numbers suggest there are more than 50 nests in East Hampton and Southampton towns combined, mostly along the north shore, where there is an abundance of fish.
Osprey are migratory raptors that travel down to the Caribbean and South America during the winter and return, in this case along the Atlantic Coast, in mid-March to their nests, typically the same nest or one in the same area. Their eggs hatch starting in late June or early July, Mr. Scheibel said.
According to Mr. Virgin, the Group for the East End, the Nature Conservancy, Southold Town, which has a dense population of osprey, and the North Fork Audubon Society have been comparing numbers and hope to put together an updated census, since the DEC no longer does census work on ospreys due to financial constraints.
Mr. Virgin said he and two staff members have been going out this month to track breeding sites with financial backing from Dwight Anderson, who manages a hedge fund called Ospraie Management. Mr. Virgin said Mr. Anderson has grown fond of the birds of prey and wants to help track down the numbers.
It is their hope to put together not only a census but also a map that tells the status of each breeding site.
“We’ll be the first ones to notice if the population changes again,” Mr. Virgin said. “We’re kind of the ones watching the community’s back.”
John Sepenoski, who manages Southold Town’s geographic information system and also tracks ospreys for the town, said he is working on the regional map and on a cellphone application that would allow birders to report ospreys they see. That information would be checked out and verified before it would be added to the map of nest locations, he said.
“It is sad to think that at one point on the North Fork of Long Island in the 1970s, we were down to only three active nests,” he said. “Osprey are an example of a success story.”
Mr. Scheibel, of like mind, said that those who championed for the birds were successful.
“Osprey is one of those species that has made it back from being endangered in the 1960s and 1970s to being quite plentiful today,” he said. “We as humans feel a strong connection with the osprey as a symbol of coastal Long Island, and have an obligation to remain vigilant protectors of their welfare.”