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Species · Washington · BBS 2025 Release · 1966–2024

Marbled Murrelet Population Trend in Washington

All statesGeneralists

Marbled Murrelet in Washington has collapsed: down 88% on the route-weighted index since 1987.

-88%Since 1987TrendPercent 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 →
4Routes 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 →
19YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Marbled Murrelet 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 →

Marbled Murrelet has collapsed in Washington: down 88% on the route-weighted index since 1987.

Marbled Murrelet Population Forecast in Washington

If the recent trend holds, Marbled Murrelet in Washington is projected to stay roughly flat through 2027, near 0.01 (95% range 0.00–0.34). A 5-year backtest shows a typical error of ±1473.4%, with 100% of held-out values landing inside the 95% band.

n/aChange by 2027TrendPercent 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 →
0.01Projected 2027 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.3495% 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 →
±1473.4%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, Marbled Murrelet in Washington is projected to stay roughly flat through 2027, near 0.01 (95% range 0.00–0.34). A 5-year backtest shows a typical error of ±1473.4%, with 100% of held-out values landing inside the 95% band.19852027
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 →
20230.030.000.35
20240.020.000.35
20250.020.000.35
20260.020.000.34
20270.010.000.34

Marbled Murrelet Survey Routes in Washington

Routes recording Marbled Murrelet 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 →
Warm Beach2720021985
Mukilteo120182015
Ozette120221991
Port Angeles120072002

Marbled Murrelet Population Trend in Other States

alaskacaliforniaoregon

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