Great and Snowy Egrets display during breeding season in the Jamaica Bay Wildlife Refuge, Queens. Photo: Don Riepe
Harbor Herons
New York City, one of the world’s great metropolises known for its bustling culture and skyscrapers, is also home to a hidden wilderness: the Harbor Heron islands. These protected wildlife sanctuaries right in our midst provide safe nesting grounds for Great and Snowy Egrets, Black- and Yellow-crowned Night-Herons, Glossy Ibis, and Little Blue and Tricolored Herons. For over 35 years, NYC Bird Alliance has monitored and advocated for the protection of these birds and their nesting and foraging habitat.
The history of the Harbor Herons program is in a sense the history of the Audubon Society itself: In New York City and Massachusetts, a movement began in the late 1800s to stop the large-scale slaughter of egrets and herons to acquire feathers for ladies’ hats, and the Audubon Society was born. The final result of this early and passionate conservation campaign was the Federal Migratory Bird Treaty Act of 1918, which has protected North American birds for over a century. Slowly, under the Act’s protection, wading bird populations rebounded in the 20th century. Fast forward to the early-1970s, when local birders were astonished to find nesting egrets on several small islands off the coast of Staten Island. NYC Bird Alliance conducted its first Harbor Herons nesting survey in 1982, and has conducted annual surveys continuously since 1985.
The discovery of breeding wading birds in New York City jumpstarted much of NYC Bird Alliance’s early habitat conservation work: our advocacy was instrumental in the preservation of nesting islands such as the Isle of Meadows and Prall’s Island in the Arthur Kill, Shooters Island in the Kill Van Kull/Newark Bay, and South Brother Island in the Bronx. (Learn more about our work to protect the Harbor Heron islands.) We hold a continuing leadership role on the Harbor Herons Subcommittee of the New York/New Jersey Harbor Estuary Program, created by the U.S. Environmental Protection Agency to protect, conserve, and restore our estuary.
State of the Harbor Herons 2023
Great Egrets on Elders East in Jamaica Bay. Photo: NYC Bird Alliance
For over 40 years, NYC Bird Alliance scientists have monitored and protected 10 species of herons, egrets, and ibis—collectively known as the Harbor Herons—that nest on wild islands throughout our City’s waterways. Learn about their nesting habits, conservation issues facing the harbor and its wildlife, and the incredible work done by NYC Bird Alliance to protect these magnificent birds by reading our annual State of the Harbor Herons report.
State of the Harbor Herons 2023
For over 40 years, NYC Bird Alliance scientists have monitored and protected 10 species of herons, egrets, and ibis—collectively known as the Harbor Herons—that nest on wild islands throughout our City’s waterways. Learn about their nesting habits, conservation issues facing the harbor and its wildlife, and the incredible work done by NYC Bird Alliance to protect these magnificent birds by reading our annual State of the Harbor Herons report.
The Hoffman Island nesting colony includes Great and Snowy Egrets and Black-crowned Night-Herons, seen above, as well as Glossy Ibis, Double-crested Cormorants, and Great Black-backed and Herring Gulls. Photo: NYC Bird Alliance
Get to Know the Harbor Herons!
As many as 10 species of wading birds nest on New York City's Harbor Heron islands, along with cormorants and gulls, which NYC Bird Alliance also monitors during its annual survey of the islands. Get to know the colonial waterbird species that call our city home.
Snowy Egret nests like this one on South Brother Island are made of fine sticks and can host as many as six eggs. Photo: Christopher Girgenti
Nesting Surveys and Recent Conservation Efforts
Since 1982, NYC Bird Alliance has been monitoring the populations of wading birds (including herons, egrets, and ibis) and other waterbirds (cormorants, gulls, and terns) on select islands in the New York/New Jersey Harbor and surrounding waterways, while also noting the presence of other nesting bird species and current nesting habitat. In the second half of May each year, an enthusiastic corps of biologists, naturalists, and community scientists access each island via boat, quickly counting nests, eggs, and/or adults, while minimizing disturbance to the birds. More than 35 years of continuous data helps us determine what species or habitats are most in need of protection—and provides a critical benchmark for future research into the effects of climate change and environmental contaminants.
Though the harbor’s wading bird population has remained fairly stable over the decades, recent years have indicated a possible decline over the survey period. In the chart below, see the total number of island-nesting pairs of wader species observed during nesting surveys conducted from 1982 to 2019. (Years with substantial uncertainty in the data—survey years that did not capture one or more of the major breeding colonies—are indicated with gray bars (1998, 2006, 2012). "}" data-trix-content-type="undefined" class="attachment attachment--content"> Total number of island-nesting pairs of wader species observed through the NYC Bird Alliance Harbor Herons nesting surveys from 1982 to 2019. Years with substantial uncertainty in the data (survey years that did not capture one or more of the major breeding colonies) are indicated with gray bars (1998, 2006, 2012). Chart: NYC Bird Alliance
Key: BCNH = Black-crowned Night-Heron; GREG = Great Egret; SNEG = Snowy Egret; GLIB = Glossy Ibis; CAEG = Cattle Egret; YCNH = Yellow-crowned Night-Heron; LBHE = Little Blue Heron; TRHE = Tricolored Heron; GRHE = Green Heron
Examination of the Harbor Herons Populations chart above reveals that in particular, our local population of Black-crowned Night-Herons has declined since the early 1990s, mirroring a decline reported by researchers regionally. In early 2020, NYC Bird Alliance provided its data to the New York State Department of Environmental Conservation to support upgrading the conservation status of Black-crowned Night-Herons in New York to “Threatened.” This change would provide greater protections to this charismatic species.
Over time, the pattern of wader nesting in the harbor has shown great variability. As can be seen in the chart below, since the early 1980s, breeding activity has shifted completely from the three “pioneer” rookeries in the Arthur Kill and Kill Van Kull (Prall’s Island, Isle of Meadows, and Shooters Island). The abandonment of these colonies occurred in the decade following the 1990 Exxon oil pipeline spill in the Arthur Kill, and may have been related to contamination from that spill.
Over the last two decades, the most populous wader colonies have included South Brother Island in the Bronx, Hoffman Island in the lower bay, and Subway Island in Jamaica Bay. In recent years, several previously productive islands have sharply declined or been abandoned: Canarsie Pol and Elders Point East Island, in Jamaica Bay; Mill Rock, in the East River, and Goose and Huckleberry Islands, in Long Island Sound. Encroachment by predators and people are possible suspects in all cases. Frequent flooding may also be a primary culprit in the lower-lying islands of Jamaica Bay: during our 2017 and 2018 surveys of Elders East Island, we found drowned Great Egret nestlings; by our 2019 survey, waders appeared to have deserted the colony. Such findings are an unsettling foreshadowing of what awaits our coastal areas in coming decades.
"}" data-trix-content-type="undefined" class="attachment attachment--content"> Nesting island trends, all wader species (1982-2019): the island colonies are arranged, in both the area chart and its legend, from the earliest colonies established, at the bottom, to the most recent, at the top. Gray bars indicate years with incomplete data (1998, 2006, 2012). Chart: NYC Bird Alliance
The continuous shifting of nesting waders around the harbor underscores the importance of protecting the current nesting islands, and of maintaining additional wild islands where the birds can move when disturbed. NYC Bird Alliance is currently working with the National Park Service and NYC Parks to increase signage on the islands of the largest colonies in order to discourage human visitation during nesting season. We will continue to be vigilant in protecting these charismatic and vulnerable species from harm.
Nesting Survey Reports
Below, view or download reports from the Harbor Herons Nesting Survey project. (“Full Reports” document “full surveys”: every three years, we survey all islands that have hosted nesting waders during the entire history of the survey. Other years, we survey only islands where nesting occurred in the prior year; those surveys are documented in “Interim Reports."
A fledgling Great Egret banded on South Brother Island in the Bronx. Photo: NYC Bird Alliance
Harbor Heron Banding Research
Since 2006, NYC Bird Alliance has banded and tagged nesting waterbird species on the Harbor Heron islands including Great Egret, Snowy Egret, Little Blue Heron, Glossy Ibis, and Double-crested Cormorant. Individually coded metal and large plastic “field-readable” bands allow us to identify individual birds and study the longevity, survival, migration, and dispersal of waterbird populations in New York Harbor. NYC Bird Alliance is participating in a global study of Glossy Ibis genetics, collecting feather samples from NYC-born Glossy Ibis, and recently published an article on Glossy Ibis nesting in the City for the inaugural issue of the research publication Stork, Ibis, and Spoonbill Conservation.
In recent years, new technologies have allowed us to track waterbird movement more continuously, via GPS technology. In collaborative research with 1000 Herons, New Jersey Audubon, and the U.S. Forest Service, we have tagged several Great Egrets and followed their movements.
Other Resources
The U.S. Army Corps of Engineers and The Port Authority of New York & New Jersey draft Comprehensive Restoration Plan for the Hudson-Raritan Estuary and the Harbor Herons Subcommittee of the Harbor Estuary Program’s Harbor Herons Conservation Plan together provide historical perspective of Harbor Herons and their breeding and foraging habitat, identify threats to the persistence of these species in the harbor, and lay out a plan of action for protecting these birds in the future.
THANK YOU TO OUR SUPPORTERS
NYC Bird Alliance’s 2023 Harbor Herons research was made possible through funding from the Hudson River Foundation, the Sarah K. de Coizart Article TENTH Perpetual Charitable Trust, and Elizabeth Woods and Charles Denholm. Critical support is also provided by the generous annual contributions of our members and donors.
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