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Species · Oregon · BBS 2025 Release · 1966–2024

Double-crested Cormorant Population Trend in Oregon

All statesWetland birds

Double-crested Cormorant in Oregon has fallen sharply: down 72% on the route-weighted index since 1971.

-72%Since 1971TrendPercent 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 →
23Routes 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 →
55YearsYears 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 OregonNotable 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 fallen sharply in Oregon: down 71% on the route-weighted index since 1971.

Double-crested Cormorant Population Forecast in Oregon

If the recent trend holds, Double-crested Cormorant in Oregon is projected to rise about 20% by 2029 — from 0.32 in 2024 to a central estimate of 0.39 (95% range 0.00–1.6). A 5-year backtest shows a typical error of ±106.8%, with 100% of held-out values landing inside the 95% band.

+20%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 →
0.39Projected 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 →
0.00–1.695% 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 →
±106.8%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 Oregon is projected to rise about 20% by 2029 — from 0.32 in 2024 to a central estimate of 0.39 (95% range 0.00–1.6). A 5-year backtest shows a typical error of ±106.8%, with 100% of held-out values landing inside the 95% band.19692029
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 →
20250.430.001.7
20260.420.001.7
20270.410.001.7
20280.400.001.6
20290.390.001.6

Double-crested Cormorant Survey Routes in Oregon

Routes recording Double-crested Cormorant in Oregon.
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 →
Glasgow2420241989
Princeton819851978
Malheur Nwr719981986
Dell Spring519891980
Elk Lake520161982
Nicolai Mtn.320241994
Modoc Point320181969
Wedderburn220241970
Barnes Val219741974
Clearwater220021991
Fish Lake220151987
Green220232023
Catlow Rim220162004
Lapham Res.120062006
Elkton119951995
Hazel Camp120221975
Emigrant Lk119861986
Blizzard Gap120161989
Coquille120242016
Harney Lake119971993
Warner Vally120211996
Sheaville120222013
Chinchalo120051995

Double-crested Cormorant Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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