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

Yellow Warbler Population Trend in California

All statesForest birds

Yellow Warbler in California has increased: up 30% on the route-weighted index since 1970.

+30%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 →
194Routes 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 Yellow Warbler Trends in CaliforniaNotable 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 Yellow Warbler in California. See the full index history below.

Yellow Warbler Population Forecast in California

If the recent trend holds, Yellow Warbler in California is projected to stay roughly flat through 2030, near 1.9 (95% range 0.93–2.9). A 5-year backtest shows a typical error of ±53%, with 80% of held-out values landing inside the 95% band.

-1%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 →
1.9Projected 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 →
0.93–2.995% 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 →
±53%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 California is projected to stay roughly flat through 2030, near 1.9 (95% range 0.93–2.9). A 5-year backtest shows a typical error of ±53%, 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 →
20261.90.962.9
20271.90.952.9
20281.90.952.9
20291.90.942.9
20301.90.932.9

Yellow Warbler Survey Routes in California

Routes recording Yellow Warbler in 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 →
Horse Creek6320191970
Genesee2920241972
Jofegan 22220252024
Hay Fork2020172003
Johnsville1820251975
Iron Gate1820191988
Longvale1520231972
Santa Ynez1120191969
Cohasset1120211972
Riverton1020251973
Tahoe Nf1019941987
Paxton1020251998
San Ysidro920191991
Mesa Grande920251970
Mccloud920211973
Chilcoot920241998
Woodfords820251974
Silver City820011993
Willow Spgs719711969
Nubieber620181970
Sawmill Mtn620221970
Carmel Val620251973
Bass Lake520111972
Tres Pinos519821968
Foster Park519941969

Yellow Warbler Population Trend in Other States

alabamaalaskaarizonaarkansascoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckymainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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