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

Double-crested Cormorant Population Trend in Idaho

All statesWetland birds

Double-crested Cormorant in Idaho has collapsed: down 76% on the route-weighted index since 1981.

-76%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 →
17Routes 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 →
41YearsYears 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 IdahoNotable 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 Idaho: down 76% on the route-weighted index since 1981.

Double-crested Cormorant Population Forecast in Idaho

If the recent trend holds, Double-crested Cormorant in Idaho is projected to rise about 699% by 2029 — from 0.08 in 2024 to a central estimate of 0.64 (95% range 0.00–1.8). A 5-year backtest shows a typical error of ±831.5%, with 100% of held-out values landing inside the 95% band.

+699%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 →
0.64Projected 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 →
0.00–1.895% 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 →
±831.5%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 Idaho is projected to rise about 699% by 2029 — from 0.08 in 2024 to a central estimate of 0.64 (95% range 0.00–1.8). A 5-year backtest shows a typical error of ±831.5%, with 100% of held-out values landing inside the 95% band.19722029
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 →
20250.620.001.8
20260.620.001.8
20270.630.001.8
20280.630.001.8
20290.640.001.8

Double-crested Cormorant Survey Routes in Idaho

Routes recording Double-crested Cormorant in Idaho.
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 →
Blackft Res620081994
Springfield620151972
Pocatello420061995
Daniels Res320001988
Naples220242014
Cedar Hill220212006
Joel220232023
Crane Creek220001995
Featherville220042001
Gifford119931993
Preston120081988
Baker120192019
Cabarton120102010
Blacks Creek120101976
Ririe119861986
Pasadena Val120161988
Mud Lake120112011

Double-crested Cormorant Population Trend in Other States

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

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