Great Gull Island

Less than a hundred miles from New York City, at the eastern end of Long Island Sound, sits Great Gull Island. On a clear day three states are visible from it: Connecticut, Rhode Island, and New York. Millions of people live within relatively close proximity, and yet it couldn’t feel further from civilization. “I call it the wildest place on the coast of the eastern United States,” says Joan Walsh, one of the primary researchers on the island. Only 17 acres, the island is home to a dense city of its own in the summer: the largest breeding colony of Common Terns in the world and the largest Roseate Tern colony in the Western Hemisphere. Think of it as Tern City.

Volunteers and researchers search for nests on Great Gull Island. Photo by Sophie Zyla.

For nearly 60 years, researchers with New York’s American Museum of Natural History and hundreds of volunteers have monitored those birds. But they haven’t only studied them; they’ve helped turn the colony into what it is today, marking one of the continent’s great conservation success stories. And as those birds face extreme challenges brought on by climate change, its researchers are looking to secure its future. Since the Roseate Terns are endangered, both in the U.S. and in Brazil, where they spend winters, Walsh says, “we have a global responsibility to maintain this population.”

Terns nested on Great Gull Island until the turn of the 20th century. In 1895, one observer estimated the tern colony at 3,500. The U.S. Army acquired it in 1897 to build a fort to guard the entrance to Long Island Sound, but their populations had already been decimated by plume hunters. The island, formed of sand and rubble left behind by the last Ice Age some 12,000 years earlier, was paved over by the Army to build concrete fortifications and permanent gun emplacements. The island’s shoreline was also armored with big granite rocks. Legend has it that those were brought over from the excavation of New York City’s first subway line, since blast marks are evident on them. The name Great Gull Island came from those terns—in the 19th century, they were known as mackerel gulls because they arrived each spring along with the fish.

Roseate Tern. Photo by Jennifer Kepler.

Roseate Terns prefer a nest with a roof over it. Photo by Margaret Rubega.

Common Terns with chicks.They prefer to nest on open or sparsely vegetated ground. Photo by Jennifer Kepler.

If they were lumped together it’s because to the naked eye they look similar. In early summer, the Roseates have a thin black bill and a pink blush to their underside and a long tail that extends well beyond their wingtips. The Commons are grayer overall, with a tail usually shorter than their wingtips, and an orange-red bill with dark tip. They’re almost the same size. But the Commons are far more aggressive in defending their territory than their cousins, a dynamic that may explain why the Roseates choose to nest alongside them. Both species migrate between South and North America.

Between the two world wars, up to 500 men were stationed on the island. A few Common Terns attempted to nest there in the first few years of military occupation, but soldiers drove them off. There was no colony when the Army left. In 1949, the museum purchased it from the government for one dollar and assigned the Linnaean Society of New York the task of returning it to a site that would attract terns again. Volunteers raked the grounds and tore down some of the structures. And then people waited for the birds to return. It didn’t take long. In 1955, a Linnaean Society member flew over the island and spotted 25 pairs of Common Terns nesting at its eastern end. The Roseates followed. In 1963, the museum’s Helen Hays visited the island for the first time. Through force of will, Hays, now a legend among ornithologists, helped turn this decimated colony into a globally important one.

Left: Helen Hays in her Great Gull Island office, 1975. Photo by Michael Male.
Right: Hays waving from Great Gull Island, 2017. Photo by Jennifer Kepler.

Hays, a native of upstate New York, had graduated from Wellesley College in 1953 and then studied Ruddy Ducks before she joined the museum staff. She worked on cataloging its specimen collection, but was far more interested in working with live birds. Brought to the island by the head of the museum’s Education department, Catherine Pessino, Hays thought it looked like a terrific place to increase the number of terns. In fact, the birds seemed to enjoy nesting right on the concrete of the old fort structures, and as long as those lasted, there would be open areas for them to nest. The Roseates especially liked to nest under the granite rocks, while the Commons preferred open spaces, like the gun emplacements. Terns were a perfect subject for Hays’ research; since they’re colonial nesters and can live beyond 25 years, she could follow the same individuals over time if they returned to Great Gull Island.

But Hays couldn’t do it alone. She jumped at the chance to recruit others, and by 1969, she had enough people willing to stay for the summer to monitor the growing colony. So began the Great Gull Island Project. Their original accommodations were the dilapidated buildings the Army had abandoned. As Hays recalled some years ago: “At the center of the island, three hollow-eyed buildings stood silent and empty, their copper gutters torn off by enterprising ‘treasure’ hunters. Rooms had been stripped of doors, windows and anything else that could be removed. The roofs of all buildings leaked, causing floor boards to rot. The bottom of an old pot-bellied stove, two coal-burning cook stoves and a few radiators were the only furnishings left in buildings which had once been offices and officers’ quarters.”

First-time volunteers would enter their lodgings and walk out moments later looking as if they had seen a ghost. Hays herself slept on a handmade bed in a building that had holes in the floor and which was nicknamed the Death Trap. She communicated to the outside world on a marine band radio. To this day, the island lacks running water or plumbing. But solar panels now provide electricity. Supplies arrived weekly on a boat from Connecticut. Hays resided on the island for six months, from April to September, for more than 50 years.

Left: A Common Tern nest with chicks, marked with a numbered tongue depressor. Photo by Jennifer Kepler.
Right: The bird banding room, 1975. Photo by Michael Male.

Hays and her team of volunteers began to learn about the terns they were sharing the island with. Each year, volunteers search for nests and mark them with numbered tongue depressors. The terns aggressively defend their territories, however, so volunteers wear a big straw hat with a high crown of plastic flowers, since terns aim for the highest point. As soon as the chicks start to hatch, the adults grow even more protective. “They have three ways to be protective,” says Walsh. “They can hit you, poop on you and scream at you.” From the beginning, volunteers banded the adults and their chicks. Those bands would turn them into individuals with known histories. The birds often return to the location of their previous year’s nest. Over time, Hays and her team were able to follow the lineage of family groups. It was the kind of data that one can only get from a long-term study.

But banding the whole island was a big job and done by sometimes up to 30 volunteers after the young hatched in early June. Between 1969 and 2014, about 400,000 birds were banded. This was backbreaking physical work. “There are larger colonies of birds out there in the world, but they were not created like this,” says Walsh. The current breeding population is made up of approximately 12,000 pairs of Common Terns and 2,200 pairs of Roseate Terns. So over 40,000 adult and young birds are typical at its peak. It’s a very noisy place.

Joan Walsh, one of the primary researchers on Great Gull Island, seen here c. 1982 Photo by Margaret Rubega.

Margaret Rubega (left), before she was a professor at the University of Connecticut. Also shown are Matthew Male (right) and Terry Getz (middle). 

Many of the volunteers have returned for decades. In 1980, Walsh was a sophomore at Southern Connecticut State College studying botany when she was invited to Great Gull Island by her chemistry lab partner, Matthew Male, who had been going with his father and three brothers since the early 1970s. Walsh knew nothing about birds, but she went for a weekend and ended up staying the summer. “The first thing they said to me was to look down,” she says. “Always look down because there are babies under your feet all the time.” Walsh ditched botany and became an ornithologist, and she has returned ever since, for many years on behalf of Mass Audubon. The same goes for Margaret Rubega, a professor at the University of Connecticut, who went to the island for the first time in 1979 and now brings her students, and Peter Paton, a professor at the University of Rhode Island who does the same, and first went to the island in 2012. The island has shaped at least two generations of scientists. “So many people came through and were trained up and went on to do remarkable stuff,” Walsh says, naming the current head of scientific integrity at the Environmental Protection Agency as well as other scientists and policymakers.

Hundreds of scientific papers have been produced from the work at Great Gull Island, charting new territory on these two species. For instance, Common and Roseate Terns will choose the same mate of the previous year, but they won’t wait around if the other doesn’t arrive on time. As they get older, though, the birds settle down with a more stable choice of mate. There have been several documented firsts. In the early years, they found several Roseate and Common Tern hybrids in the colony. On a few occasions they found Common Terns with multiple nests and they also found the first record of multiple Roseates on a single nest, in this instance a male and two females.

Hays was always looking for ways to grow the colony. In 1981, upon the suggestion of a mammologist at the museum, meadow voles were introduced to tackle the island’s thick vegetation. They ate through all of it in a few years, clearing every blade of grass and more than doubling the area for the Common Terns to place their nests. Between 1969 and 1984 there were between 1,500-2,000 pairs of Common Terns on the islands, but after the voles did their job that grew to 6,000. It’s doubled again. For the Roseate Terns, volunteers erected three sets of terraces on the sides of a gun emplacement, building wooden shelters within them to replicate the roofs of their preferred rock shelters.

Tern chicks camoflauge well on rocks and mottled ground. Photo by Jennifer Kepler.

Hays was also curious where they went to in South America, four or five thousand miles away, once they left Great Gull Island. That made up half of their lives. Her desire to solve that puzzle led to what ornithologists today call full life-cycle conservation. Beginning in 1995, Hays made trips to the coasts of Brazil and Argentina, looking for the birds they’d banded. Common Terns were seen in Punta Rasa, Argentina, while Roseate Terns, like a needle in a haystack, were found by the Abrolhos Islands seven miles off the Brazilian coast. These trips entered ornithological folklore. In both countries – and later the Azores in Portugal, where Common and Roseate Terns also nest – Hays forged connections with biologists who were monitoring this other stage of their life cycle, painting a full picture of how these citizens of the world handle a whole suite of challenges. This past winter, Walsh and researchers from National and local Brazilian e-NGOs attached GPS radios on terns in Brazil, where oil and offshore wind development pose risks to the birds. Some of those made it back to Great Gull Island.

Those challenges only grow. Twenty scientists and conservationists from the national to local level recently came together to plot, as Walsh calls it, Great Gull Island 2.0. The two main threats are biosecurity and climate change, and they’re linked. For the former, they’re doing everything they can to keep rats and mice and mammalian predators like raccoons off the island and to rid it of invasive plants. Those voles which did so well in their grass-clearing job are now seen as a possible vector for HPAI, the new highly pathogenic avian influenza, and are slated to be removed from the island. And with the help of a habitat specialist, they’ve cleared a noxious weed called wild radish that blanketed the open areas to make space for seaside goldenrod to flourish. It’s a plant that by July grows tall enough to offer shade to the tern chicks. “You could call us a seaside goldenrod preserve now,” Walsh jokes. Monarch butterflies love it, too, and thousands now stop there to feed on their nectar during their autumn migration.

Top: Wild radish, an invasive plant, blanketed much of the island in 2012. The dense tangle crowds the birds, making it difficult for them to move.

Bottom: The recent removal of wild radish and other invasives has resulted in dramatic habitat improvement. Seaslde goldenrod is now widespread. Photos by Margaret Rubega.

Top: When the goldenrod blooms in fall, the island attracts thousands of migrating monarch butterflies. Photo by Margaret Rubega.

Bottom: Goldenrod shelters chicks and provides enough space for them to move freely. Photo by Peter Paton.

Building up the island’s climate resiliency in the face of severe storms and rising sea level is the second tenet of this reboot. “We can’t change the temperature of the ocean,” Walsh says. “It’s unfortunate, but we can’t. Their prey base could change. But we can provide them with the right sort of managed habitat.” Part of the north side of the island has been lost to erosion, and the bluffs on the south side have been worn down by winter storms. Roseate Terns nest in the rocks in both areas, so Walsh says they’ve been experimenting with different wooden boxes in different configurations with the hope that the Roseates will see a box as an adequate replacement for a rock. This year, for the first time, there are more Roseates in the new boxes than in the rocks—an encouraging sign for restoration planning.

Professor Margaret Rubega's analysis of potential Roseate Tern nesting site loss due to sea level rise.

A variety of Roseate Tern nesting boxes. Photos by Margaret Rubega.

Eventually they’ll have to reinforce the shoreline, which will stir up the Roseates’ existing nesting spaces. “We have to move forward with a short-term and medium-term and long-term plan to add some resiliency to the island, so that a hundred years from now, some kid from New York City can go out there and say, ‘Man, Roseate Terns? This is the wildest place on the East Coast of the United States. And I’m only 70 miles from New York City.”

Great Gull Island remains a wild place, though now researchers have a boardwalk. Photo by Margaret Rubega.

To learn more about the Great Gull Island Project, as well as to contribute directly, please visit the Linnaean Society of New York website.

Great Gull Island is home to the world's largest nesting Common Tern colony and the largest Roseate Tern colony in the Western Hemisphere. Since its 1949 acquisition by the American Museum of Natural History, the Linnaean Society of New York has worked tirelessly to support conservation and research projects to protect these important bird populations.