BirdAnalyst
Species · Alabama · BBS 2025 Release · 1966–2024

Double-crested Cormorant Population Trend in Alabama

All statesWetland birds

Double-crested Cormorant in Alabama has surged: up 38× on the route-weighted index since 1983.

38×Since 1983TrendPercent 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 →
31Routes 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 →
34YearsYears 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 AlabamaNotable 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 Alabama: up 38× on the route-weighted index since 1983.

Double-crested Cormorant Population Forecast in Alabama

If the recent trend holds, Double-crested Cormorant in Alabama is projected to rise about 218% by 2029 — from 0.32 in 2024 to a central estimate of 1.0 (95% range 0.00–2.4). A 5-year backtest shows a typical error of ±513.3%, with 100% of held-out values landing inside the 95% band.

+218%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 →
1.0Projected 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 →
0.00–2.495% 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 →
±513.3%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 Alabama is projected to rise about 218% by 2029 — from 0.32 in 2024 to a central estimate of 1.0 (95% range 0.00–2.4). A 5-year backtest shows a typical error of ±513.3%, with 100% of held-out values landing inside the 95% band.19772029
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 →
20250.910.002.3
20260.930.002.3
20270.960.002.4
20280.980.002.4
20291.00.002.4

Double-crested Cormorant Survey Routes in Alabama

Routes recording Double-crested Cormorant in Alabama.
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 →
Wheeler Dam10220232001
Elkmont3620142014
Castleberry2320082008
Guntersville1520242001
Wedgeworth620022001
Rock Chapel520022002
Dauphin Is 2420182008
St Florian319991999
Valhermoso Spgs320101996
Pine Grove320241983
Greensboro320122012
Greensport220192000
Billingsley220082008
Alabama Pt219991977
Calebee220081997
Triana220112002
Dauphin Is 3220212021
Alabama Pt 2120152004
Kymulga120222022
Grangeburg119951995
Brundidge120042004
Dauphin Is119811981
Grove Hill119901990
Fairview119951995
Odenville120212021

Double-crested Cormorant Population Trend in Other States

alaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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