BirdAnalyst
Species · Rhode Island · BBS 2025 Release · 1966–2024

Double-crested Cormorant Population Trend in Rhode Island

All statesWetland birds

Double-crested Cormorant in Rhode Island has surged: up 179% on the route-weighted index since 1985.

+179%Since 1985TrendPercent 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 →
5Routes 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 →
28YearsYears 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 Rhode IslandNotable 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 Rhode Island: up 179% on the route-weighted index since 1985.

Double-crested Cormorant Population Forecast in Rhode Island

If the recent trend holds, Double-crested Cormorant in Rhode Island is projected to fall about 49% by 2028 — from 27 in 2023 to a central estimate of 14 (95% range 0.00–32). A 5-year backtest shows a typical error of ±1576.3%, with 60% of held-out values landing inside the 95% band.

-49%Change by 2028TrendPercent 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 →
14Projected 2028 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–3295% 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 →
±1576.3%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 Rhode Island is projected to fall about 49% by 2028 — from 27 in 2023 to a central estimate of 14 (95% range 0.00–32). A 5-year backtest shows a typical error of ±1576.3%, with 60% of held-out values landing inside the 95% band.19762028
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 →
2024130.0031
2025130.0031
2026130.0031
2027140.0031
2028140.0032

Double-crested Cormorant Survey Routes in Rhode Island

Routes recording Double-crested Cormorant in Rhode Island.
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 →
Shannock5420232022
Block Island620101988
Quonset Pt520222019
Sachuest Pt419901976
Wallum Lake120122012

Double-crested Cormorant Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniasouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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