BirdAnalyst
Species · BCR 32 · BBS 2025 Release · 1966–2024

Black-headed Grosbeak In Coastal California

All regionsCoastal CaliforniaGeneralists

Black-headed Grosbeak in Coastal California has edged down: down 16% on the route-weighted index since 1970.

-16%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 →
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 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 stay roughly flat through 2029, near 7.2 (95% range 4.1–10). A 5-year backtest shows a typical error of ±21.4%, with 100% of held-out values landing inside the 95% band.

+6%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 →
7.2Projected 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 →
4.1–1095% 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 →
±21.4%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, Black-headed Grosbeak in Coastal California is projected to stay roughly flat through 2029, near 7.2 (95% range 4.1–10). A 5-year backtest shows a typical error of ±21.4%, with 100% 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 →
20257.44.310
20267.34.310
20277.34.210
20287.24.210
20297.24.110

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
Lake SuccessCALIFORNIA331996
Bartlett SpsCALIFORNIA332018
Cuyamaca PkCALIFORNIA322024
Cal Hot SpgsCALIFORNIA312019
StonyfordCALIFORNIA292018
CohassetCALIFORNIA272024
JacksonCALIFORNIA251992
Elsinore MtnCALIFORNIA232024
San Benito Mtn.CALIFORNIA222009
RumseyCALIFORNIA212008
Point ReyesCALIFORNIA212023
Hough SpringsCALIFORNIA192007
Mt PinosCALIFORNIA182004
Green ValleyCALIFORNIA182023
TomheadCALIFORNIA172011
Yokohl ValCALIFORNIA151997
Oak GroveCALIFORNIA152024
OnoCALIFORNIA152011
Elizabeth LkCALIFORNIA152016
Foster ParkCALIFORNIA141994
FolsomCALIFORNIA142024
TujungaCALIFORNIA142021
Gold HillCALIFORNIA142024

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