BirdAnalyst
Species · Washington · BBS 2026 Release · 1966–2025

Black-headed Grosbeak Population Trend in Washington

All statesForest birds

Black-headed Grosbeak in Washington has surged: up 316% on the route-weighted index since 1970.

+316%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 →
57YearsYears 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 316% 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 2030, near 10 (95% range 8.6–12). A 5-year backtest shows a typical error of ±9.8%, with 80% of held-out values landing inside the 95% band.

-4%Change by 2030TrendPercent 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 →
10Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
8.6–1295% 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 →
±9.8%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, Black-headed Grosbeak in Washington is projected to stay roughly flat through 2030, near 10 (95% range 8.6–12). A 5-year backtest shows a typical error of ±9.8%, with 80% of held-out values landing inside the 95% band.19682030
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 →
20269.68.011
20279.88.111
20289.98.312
2029108.412
2030108.612

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 →
Mendota 23720001989
Kendall3420251981
Mendota 33320252005
Cougar3220231970
Snowden2820251973
Blewett Pass2820251995
Mukilteo2620251993
Warm Beach2520171968
Kamilche2420251968
Lake Chelan2420251988
Raymond 22320242022
Pe Ell2220251993
Vashon Is.2120251995
Everett1920251975
Carnation1920251988
Newhalem1820251968
Ellensburg1820251981
Nighthawk1820251993
Rainier1820251993
Deception1820181992
Port Angeles1620251975
Twisp1620241970
Ardenvoir1519871969
South Elma1520241975
Laurier1520251996

Black-headed Grosbeak Population Trend in Other States

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Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.