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

Black-headed Grosbeak Population Trend in Washington

All statesGeneralists

Black-headed Grosbeak in Washington has surged: up 271% on the route-weighted index since 1970.

+271%Since 1970TrendPercent 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 →
102Routes 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 →
56YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Black-headed Grosbeak 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 increasecomputed 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 →

Black-headed Grosbeak has surged in Washington: up 271% on the route-weighted index since 1970.

Black-headed Grosbeak Population Forecast in Washington

If the recent trend holds, Black-headed Grosbeak in Washington is projected to stay roughly flat through 2029, near 10.0 (95% range 8.4–12). A 5-year backtest shows a typical error of ±7.7%, with 80% of held-out values landing inside the 95% band.

+8%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 →
10.0Projected 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 →
8.4–1295% 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 →
±7.7%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, Black-headed Grosbeak in Washington is projected to stay roughly flat through 2029, near 10.0 (95% range 8.4–12). A 5-year backtest shows a typical error of ±7.7%, with 80% of held-out values landing inside the 95% band.19682029
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 →
20259.47.811
20269.57.911
20279.78.111
20289.88.211
202910.08.412

Black-headed Grosbeak Survey Routes in Washington

Routes recording Black-headed Grosbeak 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 →
Kendall3920241981
Mendota 23720001989
Pe Ell3420231993
Cougar3220231970
Mendota 33220242005
Everett2820241975
Concrete2720242013
Warm Beach2520171968
Mukilteo2520241993
Snowden2420241973
Lake Chelan2320241988
Raymond 22320242022
Vashon Is.2120241995
Newhalem2020241968
Rainier1920191993
Ellensburg1820241981
Deception1820181992
Blewett Pass1720241995
Twisp1620241970
Ardenvoir1519871969
South Elma1520241975
Bay View1420171993
Montesand1420241987
Ronald1320241973
White Chuck1320241992

Black-headed Grosbeak Population Trend in Other States

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