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Species · Louisiana · BBS 2025 Release · 1966–2024

Double-crested Cormorant Population Trend in Louisiana

All statesWetland birds

Double-crested Cormorant in Louisiana has declined: down 32% on the route-weighted index since 1975.

-32%Since 1975TrendPercent 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 →
27Routes 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 LouisianaNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

No notable trend signals for Double-crested Cormorant in Louisiana. See the full index history below.

Double-crested Cormorant Population Forecast in Louisiana

If the recent trend holds, Double-crested Cormorant in Louisiana is projected to rise about 468% by 2029 — from 0.07 in 2024 to a central estimate of 0.41 (95% range 0.00–1.4). A 5-year backtest shows a typical error of ±886.5%, with 100% of held-out values landing inside the 95% band.

+468%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 →
0.41Projected 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 →
0.00–1.495% 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 →
±886.5%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 Louisiana is projected to rise about 468% by 2029 — from 0.07 in 2024 to a central estimate of 0.41 (95% range 0.00–1.4). A 5-year backtest shows a typical error of ±886.5%, with 100% of held-out values landing inside the 95% band.19672029
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 →
20250.420.001.4
20260.420.001.4
20270.420.001.4
20280.420.001.4
20290.410.001.4

Double-crested Cormorant Survey Routes in Louisiana

Routes recording Double-crested Cormorant in Louisiana.
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 →
Creole2019871975
Gran Chenier1419821967
Esther920141988
Atchafalaya419961996
Zwolle420231998
Sabine Nwr 2320172009
Morgan City220222022
Belair220071995
Sabine Nwr220031992
Haughton120011998
Junior119911988
River Road120241995
Tensas Nwr120042004
Bickham119851985
Baton Rouge120211996
Hackberry119711971
Shaw120091990
Longstreet119901990
Forked Island 2120102010
Glencoe119981998
Ramah120121993
Kaplan120192001
Woodlawn120182016
Port Allen120112003
Frogmore120242024

Double-crested Cormorant Population Trend in Other States

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

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