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

Double-crested Cormorant Population Trend in Florida

All statesWetland birds

Double-crested Cormorant in Florida has collapsed: down 94% on the route-weighted index since 1968.

-94%Since 1968TrendPercent 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 →
92Routes 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 →
58YearsYears 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 FloridaNotable 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 declinecomputed 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 collapsed in Florida: down 94% on the route-weighted index since 1968.

Double-crested Cormorant Population Forecast in Florida

If the recent trend holds, Double-crested Cormorant in Florida is projected to fall about 100% by 2029 — from 0.25 in 2024 to a central estimate of 0.00 (95% range 0.00–2.7). A 5-year backtest shows a typical error of ±92.5%, with 100% of held-out values landing inside the 95% band.

-100%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 →
0.00Projected 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 →
0.00–2.795% 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 →
±92.5%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 Florida is projected to fall about 100% by 2029 — from 0.25 in 2024 to a central estimate of 0.00 (95% range 0.00–2.7). A 5-year backtest shows a typical error of ±92.5%, with 100% of held-out values landing inside the 95% band.19662029
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 →
20250.130.002.8
20260.050.002.8
20270.000.002.7
20280.000.002.7
20290.000.002.7

Double-crested Cormorant Survey Routes in Florida

Routes recording Double-crested Cormorant in Florida.
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 →
Plantation K8020041966
Shawano7020021987
Key West2919871987
Sugarloaf Key2720041999
Merritt Isl1320111991
Merritt Island 21320142014
Ridge Harbor1120152000
Ft Waltn Bch820081971
Scottsmoor720241968
Andytown719981974
St Augustine620141973
Pennywash Cr620172001
Key Largo619911987
Hixtown Swmp520151987
Sandy 2520162016
Shawano 2520112004
Dale Mabry419861980
Myakka Head420112002
Tamiami419711966
Lake Buffum420141990
Miccosukee320002000
Pinetta320242012
Sebastian319911988
Cross City320211989
Citrus Park320171994

Double-crested Cormorant Population Trend in Other States

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

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