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

Pigeon Guillemot Population Trend in Washington

All statesGeneralists

Pigeon Guillemot in Washington has fallen sharply: down 69% on the route-weighted index since 1973.

-69%Since 1973TrendPercent 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 →
8Routes 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 →
47YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Pigeon Guillemot 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 →

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 →

Pigeon Guillemot has fallen sharply in Washington: down 69% on the route-weighted index since 1973.

Pigeon Guillemot Population Forecast in Washington

If the recent trend holds, Pigeon Guillemot in Washington is projected to fall about 77% by 2029 — from 0.09 in 2024 to a central estimate of 0.02 (95% range 0.00–0.25). A 5-year backtest shows a typical error of ±70.5%, with 100% of held-out values landing inside the 95% band.

-77%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 →
0.02Projected 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 →
0.00–0.2595% 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 →
±70.5%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, Pigeon Guillemot in Washington is projected to fall about 77% by 2029 — from 0.09 in 2024 to a central estimate of 0.02 (95% range 0.00–0.25). A 5-year backtest shows a typical error of ±70.5%, with 100% of held-out values landing inside the 95% band.19702029
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 →
20250.040.000.27
20260.030.000.27
20270.030.000.26
20280.030.000.26
20290.020.000.25

Pigeon Guillemot Survey Routes in Washington

Routes recording Pigeon Guillemot 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 →
Deception1119981992
Ilwaco419931993
Ozette319831971
Port Angeles320241970
Warm Beach 2220242018
Mukilteo220212016
Warm Beach120161985
Vashon Is.120192000

Pigeon Guillemot Population Trend in Other States

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