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

Yellow Warbler In Coastal California

All regionsCoastal CaliforniaForest birds

Yellow Warbler in Coastal California has risen sharply: up 54% on the route-weighted index since 1970.

+54%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 →

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 →

Yellow Warbler has risen sharply in Coastal California: up 54% on the route-weighted index since 1970.

Yellow Warbler In Coastal California Population Forecast

If the recent trend holds, Yellow Warbler in Coastal California is projected to fall about 48% by 2030 — from 1.6 in 2025 to a central estimate of 0.82 (95% range 0.16–1.5). A 5-year backtest shows a typical error of ±26.1%, with 80% of held-out values landing inside the 95% band.

-48%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 →
0.82Projected 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 →
0.16–1.595% 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 →
±26.1%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, Yellow Warbler in Coastal California is projected to fall about 48% by 2030 — from 1.6 in 2025 to a central estimate of 0.82 (95% range 0.16–1.5). A 5-year backtest shows a typical error of ±26.1%, 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 →
20260.850.191.5
20270.840.181.5
20280.840.181.5
20290.830.171.5
20300.820.161.5

Routes In Coastal California

Routes recording Yellow Warbler 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 →
Jofegan 2CALIFORNIA222025
Santa YnezCALIFORNIA112019
CohassetCALIFORNIA112021
San YsidroCALIFORNIA92019
Mesa GrandeCALIFORNIA92025
Sawmill MtnCALIFORNIA62022
Carmel ValCALIFORNIA62025
Tres PinosCALIFORNIA51982
Foster ParkCALIFORNIA51994
JacumbaCALIFORNIA52025
White RiverCALIFORNIA51992
JacksonCALIFORNIA51984
Harbor Lake 2CALIFORNIA52024
Cp. PendletonCALIFORNIA42003
Cuyamaca PkCALIFORNIA42025
Elizabeth LkCALIFORNIA42016
Lake CachumaCALIFORNIA42016
Red BluffCALIFORNIA32025
FolsomCALIFORNIA32014
SangerCALIFORNIA32024
Green ValleyCALIFORNIA32023
GlennCALIFORNIA32006
LockwoodCALIFORNIA32025
OnealsCALIFORNIA32009
Angelus OaksCALIFORNIA32017

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