Harbor Herons Wading Bird Surveys: A Peek into New York City’s Wild Side

Great Egrets and Double-crested Cormorants both nest on Hoffman Island, which we found to be the second-largest wader colony in New York Harbor during the 2021 nesting season. (One Snowy Egret and one Black-crowned Night-Heron also make appearances in this photo. Can you find them?) Photo: Don Riepe 

Tod Winston | February 16, 2022

A few weekends ago, on a chilly Saturday walk in Flushing Meadows-Corona Park in Queens, a group of beginning birders came across a startling sight: 19 Great Blue Herons, clustered together along the shore of a mostly frozen Willow Lake. The “Great Blue,” the largest of our common wading birds at nearly four feet tall with a six-foot wingspan, is also the hardiest. While most “waders” fly south for the winter, this species manages to find the food it needs in unfrozen oases of water in the City. (This top-of-the-food-chain predator also sometimes resorts to other food sources, such as New York City rats!)

While the Great Blue is the most common wader here in the wintertime, it is just one of many Harbor Heron species seen regularly in New York City. In spring and summer, no matter which borough you call home, you might spot any of up to 10 species of New York City’s “charismatic megafauna”—herons, egrets, night-herons, and ibis—visiting a pond or lake in your local park.

How Did the Harbor Herons Come to Be in New York City? 

For 40 years, NYC Bird Alliance has monitored waders in New York Harbor as part of our Harbor Herons program. Their mere presence here is a great success story. In 1974, herons were discovered nesting on Shooters Island, off the northwest coast of Staten Island. 

Their arrival to our city was actually a triumphant return! Wading birds likely nested in our area historically, but several species—notably the Great Egret and Snowy Egret—were nearly wiped out in the 19th century by hunters seeking the birds’ long plumes to adorn ladies’ hats. The National Audubon Society was founded to protect these birds, leading to the passage of the Migratory Bird Treaty Act in 1918. That critical legislation, along with the Clean Water Act of 1972, led to a more hospitable New York City that could welcome these birds back to their ancestral breeding grounds.

Harbor Herons Survey Leader Tod Winston finds a Great Egret nest on South Brother Island. Photo: Debra Kriensky
Our Work Monitoring the Harbor Herons

Nesting waders have expanded across the harbor since the 1970s, and over time have shifted from their original colonies off Staten Island to several other sets of islands in the East River, the lower harbor, and Jamaica Bay. NYC Bird Alliance has continued to monitor the colonies as part of our yearly nesting survey. With a small team of ecologists and volunteers, we travel to up to 20 harbor islands by boat in the second half of May. 

These small islands, unknown to most New Yorkers, are completely wild habitats where several wader species may nest together in a tangle of trees, shrubs, and vines, often in close quarters with nesting Double-Crested Cormorants. Additionally, Herring and Great Black-backed Gulls, waterfowl like Mallard, American Black Duck, and Gadwall, and shorebirds such as Willet, American Oystercatcher, and Spotted Sandpiper all nest directly on the ground within these colonies. We have to watch our step as we quickly count birds and nests, doing our best to minimize disturbance to the breeding birds.

Glossy Ibis, photographed here during our Jamaica Bay survey on June 19, 2021, unfortunately saw their numbers fall to an all-time survey low of 37 pairs this year. Though numbers of this species tend to fluctuate, their NYC population seems to have declined in recent years for reasons we don’t yet understand. Photo: Don Riepe
What We Learned about Our Nesting Harbor Herons in 2021

After canceling our 2020 survey because of the pandemic, we were very excited to get back out to the islands last year. We’ve just published our 2021 survey report; here are some highlights: 

  • Eight species of waders nested on seven islands in the harbor in 2021.
  • Wader species found on the islands, from most to lead abundant, were Black-crowned Night-Heron (537 nesting pairs), Great Egret (370), Snowy Egret (238), Glossy Ibis (37), Little Blue Heron (7), Green Heron (3), Great Blue Heron (2), and Yellow-crowned Night-Heron (1). Great Blue Heron, which nested on Hoffman Island this year, was found nesting on the islands just twice before.
  • Yellow-crowned Night-Herons have shifted to mainland sites in recent decades: We found 83 pairs nesting at several mainland colonies in New York City, including two large colonies in the middle of housing developments in the Rockaways. Just one pair nested on the islands last year. Twenty-four additional pairs nested in New Jersey.
  • A total count of 1,195 island-nesting wader pairs indicates a stable breeding population in the Harbor compared to our 2019 survey, when we counted 1,186 pairs.
  • An apparent wader population decline over the last three decades seems primarily attributable to a long-term decline in Black-crowned Night Heron, with a smaller effect attributable to a decline in Glossy Ibis, which reached a survey low this year. We hope to explore possible reasons for these declines through upcoming analysis of our long-term data set. Other principal wader species populations appear to be stable or increasing in numbers over this period.
  • 99.7% of island-nesting waders in the harbor were concentrated on six islands in 2021: South Brother Island in the East River/Long Island Sound, Hoffman Island in the lower harbor, and four islands in Jamaica Bay. Previously abandoned colonies that continued to exhibit little to no nesting activity included Mill Rock, North Brother, Goose, and Huckleberry Islands in the East River/Long Island Sound; Canarsie Pol in Jamaica Bay; and Isle of Meadows, Prall’s Island, and Shooters Island in the Arthur Kill/Kill Van Kull.

This adult Yellow-crowned Night-Heron, photographed in Brooklyn in May 2021, likely nests in or around Jamaica Bay. This species, which feeds on crustaceans taken from tidal creeks, mostly nests in residential neighborhoods. Photo: Ryan Mandelbaum
The Value of Our Surveys

NYC Bird Alliance’s survey of the City’s nesting colonies has created a rare multi-decade database of the shifting populations of wader and waterbird species in New York City. Over the years, our data on these birds has helped us preserve several nesting islands, including the original Staten Island colonies and North and South Brother Islands in the East River. We supply our data to city and state agencies to advocate for higher protections for declining species like Black-crowned Night-Heron. 

In addition to monitoring these islands, we continue to work to keep these remarkable habitats free from disturbance by people during the nesting season to allow these beautiful and vulnerable species to successfully reproduce. Please keep off these islands in New York Harbor and let them remain wild!

View the full 2021 Report

Visit our Harbor Herons page to view and download the 2021 Survey Report, including summaries of all the islands we monitor and a write-up of each species.

-Tod Winston, Harbor Herons Survey Leader (2014-2021)