BirdAnalyst
Species · New York · BBS 2025 Release · 1966–2024

Double-crested Cormorant Population Trend in New York

All statesWetland birds

Double-crested Cormorant in New York has surged: up 267% on the route-weighted index since 1987.

+267%Since 1987TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology →
25Routes In StateSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
37YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Double-crested Cormorant Trends in New YorkNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

long arc increasecomputed indexTrend sourceWhether the figure is our own computed route-weighted index or an official USGS modeled estimate. The current build labels every trend as computed.Full methodology →

Double-crested Cormorant has surged in New York: up 267% on the route-weighted index since 1987.

Double-crested Cormorant Population Forecast in New York

If the recent trend holds, Double-crested Cormorant in New York is projected to rise about 104% by 2029 — from 0.15 in 2024 to a central estimate of 0.31 (95% range 0.00–1.1). A 5-year backtest shows a typical error of ±38.3%, with 100% of held-out values landing inside the 95% band.

+104%Change by 2029TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology →
0.31Projected 2029 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–1.195% range95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →
±38.3%Backtest errorBacktest errorTypical error when we hold out the most recent years, forecast them, and compare to what actually happened. Lower means a more trustworthy projection.Full methodology →
If the recent trend holds, Double-crested Cormorant in New York is projected to rise about 104% by 2029 — from 0.15 in 2024 to a central estimate of 0.31 (95% range 0.00–1.1). A 5-year backtest shows a typical error of ±38.3%, with 100% of held-out values landing inside the 95% band.19822029
Projection of the recent trend (dashed) with 80/95% bands — a projection, not a prediction. Habitat, climate, and land use are not modeled.
YearProjected indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →95% low95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →95% high95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →
20250.300.001.1
20260.300.001.1
20270.310.001.1
20280.310.001.1
20290.310.001.1

Double-crested Cormorant Survey Routes in New York

Routes recording Double-crested Cormorant in New York.
Recent countThe raw number of individuals recorded on this route in its most recent survey year. A single-route tally, not a trend.Full methodology →
St Johnsburg919981998
Hamburg820132000
Highland720222000
Ogdensburg620241996
Westhampton520061982
Huntington420231987
Ghent420042004
Cayuga419901990
Macdougall420211999
Purdy320092009
Crescent320191999
Jones Beach220131987
Bedford219951992
Westbrookvle120062006
E Newark120182018
Branchport120152015
Cherry Hill120142014
Cicero Ctr120101988
Salem120242014
North Easton120131991
Wanakena120142014
Willsboro120191995
Philadelphia120242004
Downsville120172017
Milford120081994

Double-crested Cormorant Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22.