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

Western Tanager In Coastal California

All regionsCoastal CaliforniaForest birds

Western Tanager in Coastal California has declined: down 32% on the route-weighted index since 1970.

-32%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 →
86Routes 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 Western Tanager in Coastal California. See the full index history below.

Western Tanager In Coastal California Population Forecast

If the recent trend holds, Western Tanager in Coastal California is projected to rise about 54% by 2030 — from 1.3 in 2025 to a central estimate of 2.1 (95% range 0.69–3.4). A 5-year backtest shows a typical error of ±41.9%, with 100% of held-out values landing inside the 95% band.

+54%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 →
2.1Projected 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 →
0.69–3.495% 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 →
±41.9%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, Western Tanager in Coastal California is projected to rise about 54% by 2030 — from 1.3 in 2025 to a central estimate of 2.1 (95% range 0.69–3.4). A 5-year backtest shows a typical error of ±41.9%, 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 →
20262.10.723.5
20272.10.723.4
20282.10.713.4
20292.10.703.4
20302.10.693.4

Routes In Coastal California

Routes recording Western Tanager 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 →
Hough SpringsCALIFORNIA382007
StonyfordCALIFORNIA312018
FallsvaleCALIFORNIA241981
CohassetCALIFORNIA212025
JacksonCALIFORNIA161984
Mt BaldyCALIFORNIA152024
Bartlett SpsCALIFORNIA142018
ValyermoCALIFORNIA132019
Angelus OaksCALIFORNIA122017
Green ValleyCALIFORNIA112023
TehamaCALIFORNIA102022
TomheadCALIFORNIA102011
CalpellaCALIFORNIA81986
RumseyCALIFORNIA82008
Point ReyesCALIFORNIA82008
White RiverCALIFORNIA71992
Waterman GapCALIFORNIA72025
Santa YnezCALIFORNIA62014
Lake HemetCALIFORNIA61986
Cuyamaca PkCALIFORNIA62025
Lake SuccessCALIFORNIA51996
Big BearCALIFORNIA51986
Mesa GrandeCALIFORNIA52025
ColmaCALIFORNIA41968
FolsomCALIFORNIA42023

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