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

Double-crested Cormorant Population Trend in Washington

All statesWetland birds

Double-crested Cormorant in Washington has held roughly steady: down 7% on the route-weighted index since 1976.

-7%Since 1976TrendPercent 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 →
38Routes 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 →
45YearsYears 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 WashingtonNotable 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 Washington. See the full index history below.

Double-crested Cormorant Population Forecast in Washington

If the recent trend holds, Double-crested Cormorant in Washington is projected to rise about 549% by 2029 — from 0.26 in 2024 to a central estimate of 1.7 (95% range 0.00–4.7). A 5-year backtest shows a typical error of ±729.4%, with 100% of held-out values landing inside the 95% band.

+549%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 →
1.7Projected 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 →
0.00–4.795% 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 →
±729.4%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 Washington is projected to rise about 549% by 2029 — from 0.26 in 2024 to a central estimate of 1.7 (95% range 0.00–4.7). A 5-year backtest shows a typical error of ±729.4%, 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 →
20251.60.004.6
20261.60.004.6
20271.70.004.6
20281.70.004.7
20291.70.004.7

Double-crested Cormorant Survey Routes in Washington

Routes recording Double-crested Cormorant in Washington.
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 →
Port Angeles4720161978
Hanford Site3919961991
South Elma2020162016
Moses Lake1220171990
Potholes620151996
Mesa620041999
Kamilche520092009
Horn Rapids520242005
Raymond520052005
Turnbull Nwr420191997
Deception319971993
Columbia Nwr320221992
Mercer320031998
Ilwaco320241993
Scootney Reservoir320192010
Malden319991999
Mukilteo320172016
Ozette219861971
Taholah220051969
Harrington220122000
Raymond 2220222022
Cusick220242017
Othello219911990
Keystone220242007
Odessa220081996

Double-crested Cormorant Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawest-virginiawisconsinwyoming

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