Listening in on the Birds of New York City

As our boat rounded a corner, a sandy shore dotted with large stones came into view. A hazy heat shimmer reflected at us from the beach, and Black-backed Gulls hulked formidably on shore, shrieking us away from their wandering, nearly full-grown chicks. A pair of American Oystercatchers joined the chorus of voices, presumably watching over their own young, and dozens of herons and egrets stirred in the trees. The smell of breeding birds was overpowering, and I felt as if I was laying eyes on an uninhabited tropical island.

But I wasn’t in the tropics, not even close. In fact, I was a few hundred yards offshore from Rikers Island, in New York Harbor, surrounded by clean water and a phenomenal abundance of life. We’d just finished deploying autonomous recording units (ARUs) along the Bronx River, where instead of oozing sewer sludge and Ninja Turtles, we’d found roosting night herons and a large snapping turtle.

American Bird Conservancy (ABC) is using ARUs along these waterways around New York Harbor to understand and document returning birdlife returning to the area as it recovers. Working in close collaboration with the Billion Oyster Project, Newtown Creek Alliance, y Alianza de Aves de Nueva York, we are listening in on the birds nesting in the trees and rocks along the shores, and to those pausing to rest and rejuvenate as they undertake their long-distance journeys from breeding grounds in the Arctic to wintering grounds in Latin America and the Caribbean. The harbor, too, is on its own kind of hero’s journey.

When Europeans first sailed into New York Harbor, they found vast and phenomenally productive oyster beds, bountiful fish, whales, and a bewildering array of bird life. It was quite literally one of the most biologically productive and exuberant places on Earth. Fed by the Hudson River to the north, to the east by the tidal strait of the East River, and by dozens of creeks that empty into the estuary, it is, even today, a wild landscape of swirling brackish water. As Europeans settled the region (displacing the native Lenape people in the process), they established farms, channelized the waterways, and ultimately established the first industry in what would become the United States of America. In turn, the waterways of the New York City Estuary became a dumping ground for tanneries, sugar refineries, canneries, and copper wiring plants, amongst other early keystone industries. Within 250 years, the landscape was ruined — ship captains could count on a stay in the harbor to kill off and clean parasites from their hulls. In the 1960s and 1970s, a series of laws were passed, including the Pure Waters Bond Act and the Clean Water Act, to improve the health of the harbor, but many still perceive its waters as toxic and polluted, devoid of life (except the mutant Ninja Turtle variety). The truth, however, is that those laws and other, more directed restoration efforts are allowing life to not only return to the estuary, but to even thrive in some places.

ARUs help us measure the outcome of these efforts. Using ABC’s Índice BirdsPlus, we are examining how the avian diversity in these riparian habitats compares to that in the surrounding areas. Our aim is to put a number on the value these improving habitats provide to biodiversity and, ultimately, to regional ecosystem services. In other words, we want to measure how increased biodiversity also contributes to human well-being in the form of cleaner water and air, nutrient cycling, or even the pure enjoyment of these places by people.

The story of the estuary around New York City is largely one of resilience, of simply providing an unpolluted and undisturbed place for nature to recover. The pace of this recovery has been accelerated by the active efforts of a number of conservation and community-led initiatives. One such leader in this space is the Billion Oyster Project, a remarkable initiative partnering with over a hundred NYC schools, tens of thousands of volunteers, and dozens of restaurants to restore oysters to New York Harbor. Oyster beds provide a three-dimensional reef structure that harbors a multitude of life, including tunicates (a type of marine invertebrate), crabs, and fish. This life, in turn, feeds birds like terns, which have returned in droves to nest in places like Governors Island. Oysters are filter feeders, removing pollutants and excess nitrogen from the water in the process; the very presence of these oyster beds provides New Yorkers with a key ecosystem service. Although water quality remains a persistent problem, with many combined sewer overflows (CSOs) regularly dumping raw sewage into the harbor, the waters in New York Harbor are cleaner than they have been in over a century, thanks, in part, to the efforts of the Billion Oyster Project and the 18 active restoration sites they have created to date.

The creeks that feed New York Harbor vary in their current levels of recovery. The Bronx River, for example, is largely forested today along the banks of its mouth. Belted Kingfishers and nesting Yellow Warblers can be heard from the water, and dozens of Black-crowned and Yellow-crowned Night Herons fly in front of passing boats. In the East River, South Brother Island, which was once the site of New York City’s first dump, now hosts nesting herons, egrets, gulls, cormorants, and even American Oystercatchers. North Brother Island, which for more than a hundred years housed those suffering from contagious diseases such as smallpox and tuberculosis, is now home to a similarly impressive array of nesting birds. NYC Bird Alliance has been monitoring these protected and off-limits heron nesting sites for over 40 years, and has been witness to impressive recoveries over that time.

Other sites are slowly recovering from a much more severe state of degradation. Newtown Creek, for example, endured a massive underground oil spill, copper contamination from adjacent superfund sites holding hazardous waste, and a channel that has been completely encased in bulkheads, leading to low rates of dissolved oxygen and water flow. Yet even here, owing in large part to the tremendous efforts of the Newtown Creek Alliance, life is returning. Crabs can be found at the mouth, oysters are slowly spreading up the creek, and wetland plants are returning to dilapidated bulkheads. The group has been experimenting, successfully, with replanting saltmarsh grass along portions of shoreline, and is creating structures and encouraging filter-feeding mussels to colonize them. Cormorants and night herons can be found well upstream, and hundreds of Barn Swallows nest along the channel. Slowly but surely, life is returning to Newtown Creek.

By placing ARUs throughout these waterways, ABC is creating an acoustic baseline we can revisit as biodiversity continues to find its way back to the nooks and crannies of recovering habitat that have grown and revitalized these historically overharvested and polluted waterways. Using the BirdsPlus Index, we can compare the birdlife of New York Harbor to regional expectations, documenting the biodiversity value these recovering habitats quietly provide to millions of unacquainted New Yorkers.

Already, of course, thousands of clued-in birders take advantage of these habitats daily — tens of thousands of eBird checklists have already been submitted from along the waterfront. Over time, with repeated acoustic sampling from ABC, we will be able to use these recordings to track biodiversity as it recovers. Moving forward, with continued legislation to protect our waters, air, and wildlife, Herculean restoration efforts of groups like the Billion Oyster Project and the Newtown Creek Alliance and their dedicated volunteers, and data to guide their efforts, these areas are poised to make a remarkable recovery. While entirely foreign to most New Yorkers, birding these creeks by kayak or canoe is already possible today.  New York Harbor’s transformation is proof that nature is resilient, and given a chance, it will thrive.