recent findings about the state of Heron Colonies in New York Harbor

Decades of Littoral Society boat support to the NYC Bird Alliance Harbor Herons surveys advances important recent findings about the state of today’s Heron Colonies in New York Harbor ​

Great Egret Chick. Photo credit: Don Riepe

For decades, the return of herons, egrets, and ibises to New York Harbor stood as a symbol of environmental recovery. After disappearing from the region during the era of severe pollution and habitat loss prior to the 1970’s, these birds rebounded following the Clean Water Act and became one of the clearest signs that the harbor ecosystem was improving. However, a new 22-year study spearheaded by the science and conservation team at NYC Bird alliance has revealed a troubling reversal: the Northeast's largest breeding population of colonial wading birds has declined by 27%, with losses driven primarily by dramatic drops in black-crowned night herons and glossy ibises. Most concerning is the black-crowned night heron, a longtime icon of New York City's waterways, whose population has fallen by more than half and could disappear locally in the next few decades if current trends continue.

The critical long-term study known widely among the local ornithological community as the annual “Harbor Heron’s Survey” has been made possible over the years by a truly outstanding and enduring collaborative effort between the NYC Bird Alliance, their partners across academic institutions, City, State and Federal agencies, local experts, non-profit organizations, volunteers, the Hudson River Foundation, and of course the American Littoral Society!

​Over the last 20 years, Don Riepe, the American Littoral Society’s Jamaica Bay Guardian and captain of the Society’s NY program boat has been providing critical boat support to ferry scientists and volunteers from the NYC Bird alliance to known isolated heron colony islands across New York Harbor, thus enabling researchers conduct long-term monitoring survey efforts detailed in the recent scientific paper linked at the end of this story.   ​

Don Riepe with the Jamaica Bay Guardian

The findings from the recently published study by Dustin Partridge of the NYC Bird Alliance and his collaborators raise important questions about the health of the New York–New Jersey Harbor ecosystem. Colonial wading birds are considered indicator species, meaning their populations reflect broader environmental conditions as they play key ecological roles in nutrient cycling, food web dynamics, and connecting aquatic and terrestrial habitats. Researchers point to several possible causes for the recent declines, including lingering pollution, habitat degradation, climate-related impacts, rising sea levels, nest predation by raccoons, competition for nesting space, and human disturbance on protected island colonies. While some species, such as great egrets and snowy egrets, are increasing, their gains are being overwhelmed by the steep losses of black-crowned night herons.

​Despite the alarming trends, researchers emphasize that there is still time to act. The study calls for stronger conservation measures, including improved habitat management, pollution monitoring, predator control, and enhanced legal protections for black-crowned night herons in New York State. Future research will be critical in identifying the root causes of the declines and determining whether similar losses are occurring across the broader Northeast region. Just as past environmental policy and advocacy helped bring wading birds like Egrets, Herons and Ibises back half a century ago. Scientists and conservationists hope that timely action now can once again alter the current projected trajectory of these birds, ensuring that these distinctive harbor residents remain part of New York’s natural heritage for generations to come. 

Ibis and heron at BJ Pond. Photo credit: Don Riepe

You can read the recent scientific publication here

And you can read the follow-up recent New York Times article here