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Great Egret Nesting Pairs Increased 96% While Black-crowned Night Herons Fell 55% in New York–New Jersey Harbor

Great egret displaying breeding plumes on a nest in Ocean City, New Jersey
Conservation · Population & status

A 22-year census of colonial wading birds in New York, USA–New Jersey Harbor found sharply contrasting trends among its most common species. From 2000 to 2022, the modelled number of nesting pairs of great egret (Ardea alba) increased by 96% and snowy egret (Egretta thula) by 26%, while black-crowned night heron (Nycticorax nycticorax) declined by 55% and glossy ibis (Plegadis falcinellus) by 59%. The study was first published on 3 June 2026 in Conservation Science and Practice.

Researchers used complete nest censuses from all known breeding locations in the harbor. The analysis focused particularly on the four most abundant species, which together accounted for 96% of the observations in the dataset. Years with only partial surveys were excluded from the trend models, and no survey was conducted in 2020 because of COVID-19 restrictions.

Egrets increased as night herons and ibises declined

For great egret, the model estimated an increase from 238 nesting pairs in 2000 to 467 in 2022, a gain of 229 pairs. Snowy egret increased from 220 to 277 pairs, a gain of 57. The authors suggest that these increases may partly continue the long recovery of the two egret species following legal protection and improvements in water quality during the twentieth century.

The pattern was very different for black-crowned night heron. Its modelled nesting population fell from 1,038 pairs in 2000 to 472 in 2022, a loss of 566 pairs. Glossy ibis declined from 266 to 109 pairs. Because black-crowned night heron has historically been the most numerous colonial wading bird in the harbor, its decline was a major driver of the 27% decrease in the overall nesting population of wading birds during the study period.

Nest counts and modelled trends for the four most common wading bird species
Nesting pairs of black-crowned night heron (a), glossy ibis (b), great egret (c) and snowy egret (d), 2000–2022. Points show survey counts; blue lines show modelled trends with uncertainty ranges. Figure 3 from Partridge et al. (2026), CC BY 4.0.

The number of active breeding colonies did not show a significant trend and remained around six colonies on average. The decline therefore reflected fewer nesting birds rather than a simple disappearance of nesting islands.

Projections if the declines continue

The researchers also projected what continued declines could mean for the two decreasing species. A linear extrapolation placed possible local loss of breeding black-crowned night heron as early as 2037 and glossy ibis in the mid-2030s. A separate population-viability model estimated when numbers might fall to 5% of each species’ maximum abundance during 2000–2022, with median dates of 2077 for black-crowned night heron and 2048 for glossy ibis. The authors emphasize that uncertainty around these projections was wide.

They discuss several possible pressures that require further investigation, including contaminants, competition for nesting space, changes in vegetation on colony islands and increasing predators. The authors conclude that the rapid decline of black-crowned night heron in what remains the largest breeding population in the northeastern United States requires immediate conservation attention.

Sources and image credit

  1. Partridge, D., Curley, S. R., Winston, T., Ramírez-Garofalo, J. R., Allen, M. C., Tobón, E., Kerlinger, P., Craig, E., & Elbin, S. B. (2026). Steep declines of colonial wading birds in northeastern North America's largest breeding population. Conservation Science and Practice, 8(7), e70316. https://doi.org/10.1111/csp2.70316Published 3 June 2026. Nest censuses from New York–New Jersey Harbor, 2000–2022, with species-specific trends and projections under continued decline.

Image: Rhododendrites — wild great egret displaying aigrettes on a nest in Ocean City, New Jersey, 1 May 2026; Wikimedia Commons; representative nesting image from New Jersey, not a nest from the census dataset; cropped to 16:9 · CC BY-SA 4.0 — https://creativecommons.org/licenses/by-sa/4.0/ · Source

About this content: This story was produced with AI assistance within an editorial workflow developed by Wildlife Vagabond. Editorial responsibility remains with Wildlife Vagabond.How AI is used

Population & status

SPECIES IN THIS STORY

Species in this story

Great Egret Ardea alba Explore species Snowy Egret Egretta thula Explore species Black-crowned Night Heron Nycticorax nycticorax Explore species

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