BirdAnalyst
Species · BCR 32 · BBS 2026 Release · 1966–2025

Black-headed Grosbeak In Coastal California

All regionsCoastal CaliforniaForest birds

Black-headed Grosbeak in Coastal California has edged down: down 13% on the route-weighted index since 1970.

-13%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 →
114Routes In RegionSurvey 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 SignalsNotable 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 Black-headed Grosbeak in Coastal California. See the full index history below.

Black-headed Grosbeak In Coastal California Population Forecast

If the recent trend holds, Black-headed Grosbeak in Coastal California is projected to rise about 10% by 2030 — from 6.4 in 2025 to a central estimate of 7.0 (95% range 4.0–10). A 5-year backtest shows a typical error of ±19.1%, with 100% of held-out values landing inside the 95% band.

+10%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 →
7.0Projected 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 →
4.0–1095% 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 →
±19.1%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 Coastal California is projected to rise about 10% by 2030 — from 6.4 in 2025 to a central estimate of 7.0 (95% range 4.0–10). A 5-year backtest shows a typical error of ±19.1%, with 100% 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 →
20267.24.210
20277.24.210
20287.14.110
20297.14.010
20307.04.010

Routes In Coastal California

Routes recording Black-headed Grosbeak in Coastal California.
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 →
Mt BaldyCALIFORNIA692024
White RiverCALIFORNIA491992
Cuyamaca PkCALIFORNIA422025
Lake SuccessCALIFORNIA331996
Bartlett SpsCALIFORNIA332018
Cal Hot SpgsCALIFORNIA312019
StonyfordCALIFORNIA292018
JacksonCALIFORNIA251992
San Benito Mtn.CALIFORNIA222009
RumseyCALIFORNIA212008
Carmel ValCALIFORNIA212025
Hough SpringsCALIFORNIA192007
Mt PinosCALIFORNIA182004
Green ValleyCALIFORNIA182023
CohassetCALIFORNIA172025
Elsinore MtnCALIFORNIA172025
TomheadCALIFORNIA172011
Yokohl ValCALIFORNIA151997
OnoCALIFORNIA152011
Elizabeth LkCALIFORNIA152016
Foster ParkCALIFORNIA141994
TujungaCALIFORNIA142021
AlamarCALIFORNIA142017
Point ReyesCALIFORNIA132025
Lake CachumaCALIFORNIA132016

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