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Species · California · BBS 2026 Release · 1966–2025

Warbling Vireo Population Trend in California

All statesForest birds

Warbling Vireo in California has increased: up 34% on the route-weighted index since 1970.

+34%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 →
182Routes 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 Warbling Vireo 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 Warbling Vireo in California. See the full index history below.

Warbling Vireo Population Forecast in California

If the recent trend holds, Warbling Vireo in California is projected to rise about 47% by 2030 — from 3.4 in 2025 to a central estimate of 5.0 (95% range 3.4–6.7). A 5-year backtest shows a typical error of ±43.6%, with 20% of held-out values landing inside the 95% band.

+47%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 →
5.0Projected 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 →
3.4–6.795% 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 →
±43.6%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, Warbling Vireo in California is projected to rise about 47% by 2030 — from 3.4 in 2025 to a central estimate of 5.0 (95% range 3.4–6.7). A 5-year backtest shows a typical error of ±43.6%, with 20% 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 →
20264.93.36.6
20275.03.36.6
20285.03.36.6
20295.03.36.7
20305.03.46.7

Warbling Vireo Survey Routes in California

Routes recording Warbling Vireo 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 →
Waterman Gap3720251972
Honeydew3420171968
Point Reyes3020251970
Genesee2420241972
Pescadero2320251992
Carmel Val2120251973
Johnsville1720251975
Woodfords1720251973
Fairfax1620241972
Alderpoint1620121974
Riverton1520251973
Tuolumne Grove1320251972
Bartle1320211972
Meadow Valley1320251999
Horse Creek1220191971
Holmes1220251968
Macdoel1220191974
Cottage Spgs1119681968
Dardanelle1120191972
Butte Meadow1020141972
Laytonville1020251972
Little Truckee1020251997
Hay Fork1020132005
Strawberry1020191999
Stonyford1020182015

Warbling Vireo Population Trend in Other States

alabamaalaskaarizonaarkansascoloradoconnecticutdelawareidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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