BirdAnalyst
Species · California · BBS 2025 Release · 1966–2024

Yellow Warbler Population Trend in California

All statesForest birds

Yellow Warbler in California has held roughly steady: up 7% on the route-weighted index since 1970.

+7%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 →
193Routes 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 →
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 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 rise about 16% by 2029 — from 1.7 in 2024 to a central estimate of 1.9 (95% range 0.93–2.9). A 5-year backtest shows a typical error of ±54.1%, with 80% of held-out values landing inside the 95% band.

+16%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 →
1.9Projected 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 →
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 →
±54.1%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 California is projected to rise about 16% by 2029 — from 1.7 in 2024 to a central estimate of 1.9 (95% range 0.93–2.9). A 5-year backtest shows a typical error of ±54.1%, with 80% 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 →
20251.90.962.9
20261.90.962.9
20271.90.952.9
20281.90.942.9
20291.90.932.9

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
Hay Fork2020172003
Iron Gate1820191988
Jofegan 21720242024
Longvale1520231972
Johnsville1320241975
Santa Ynez1120191969
Cohasset1120211972
Paxton1120241998
Tahoe Nf1019941987
San Ysidro920191991
Mesa Grande920241970
Mccloud920211973
Chilcoot920241998
Anza Borrego820241993
Silver City820011993
Willow Spgs719711969
Little Truckee720231997
Nubieber620181970
Sawmill Mtn620221970
Bass Lake520111972
Tres Pinos519821968
Foster Park519941969
White River519921972

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 2026-05-22.