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

Double-crested Cormorant Population Trend in New Jersey

All statesWetland birds

Double-crested Cormorant in New Jersey has surged: up 145% on the route-weighted index since 1981.

+145%Since 1981TrendPercent 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 →
24Routes 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 →
43YearsYears 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 JerseyNotable 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 Jersey: up 145% on the route-weighted index since 1981.

Double-crested Cormorant Population Forecast in New Jersey

If the recent trend holds, Double-crested Cormorant in New Jersey is projected to rise about 82% by 2029 — from 0.43 in 2024 to a central estimate of 0.78 (95% range 0.00–3.9). A 5-year backtest shows a typical error of ±100.1%, with 80% of held-out values landing inside the 95% band.

+82%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 →
0.78Projected 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 →
0.00–3.995% 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 →
±100.1%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 Jersey is projected to rise about 82% by 2029 — from 0.43 in 2024 to a central estimate of 0.78 (95% range 0.00–3.9). A 5-year backtest shows a typical error of ±100.1%, with 80% of held-out values landing inside the 95% band.19712029
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 →
20250.830.004.0
20260.820.004.0
20270.810.004.0
20280.790.003.9
20290.780.003.9

Double-crested Cormorant Survey Routes in New Jersey

Routes recording Double-crested Cormorant in New Jersey.
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 →
Pedricktown1020061991
Ocean City820241979
Bennett Mill419981998
New Bedford420121994
Toms River320221996
Bloomsbury320181997
High Point320031994
Dover320222000
Cranbury220101995
Woodbury Hgt120242024
Greenwich120232013
Six Points120222022
Albion119881988
Sandbrook120231989
Holmansville119711971
Midvale120141996
Kemah Lake120022002
Keyport119921992
Roosevelt120162015
Friendship119951982
Pedricktown 2120152013
Cape May Ch120101992
Winslow119961996
Ramseysburg120002000

Double-crested Cormorant Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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