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

Virginia's Warbler Population Trend in Arizona

All statesForest birds

Virginia's Warbler in Arizona has surged: up 152% on the route-weighted index since 1970.

+152%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 →
24Routes 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 →
55YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Virginia's Warbler Trends in ArizonaNotable 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 →

Virginia's Warbler has surged in Arizona: up 152% on the route-weighted index since 1970.

Virginia's Warbler Population Forecast in Arizona

If the recent trend holds, Virginia's Warbler in Arizona is projected to fall about 25% by 2030 — from 1.0 in 2025 to a central estimate of 0.78 (95% range 0.00–4.2). A 5-year backtest shows a typical error of ±284%, with 100% of held-out values landing inside the 95% band.

-25%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 →
0.78Projected 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 →
0.00–4.295% 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 →
±284%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, Virginia's Warbler in Arizona is projected to fall about 25% by 2030 — from 1.0 in 2025 to a central estimate of 0.78 (95% range 0.00–4.2). A 5-year backtest shows a typical error of ±284%, 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 →
20260.940.004.3
20270.900.004.3
20280.860.004.3
20290.820.004.2
20300.780.004.2

Virginia's Warbler Survey Routes in Arizona

Routes recording Virginia's Warbler in Arizona.
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 →
Pomerene1720041995
Prescott1020251974
Aztec Peak1019781974
Tonto Vill.920251994
Mt. Graham920251995
Happy Jack820251999
Williams320252001
Skull Valley320111996
Portal220251978
Blue219911975
Sunizona219961968
House Rock119741974
Black Mesa119921992
Rucker119971996
Flagstaff119911990
Sawmill120142005
Mormon Lake119751968
Dry Park120042000
Maine119971997
Forest Lakes120251994
Alpine120181996
Seligman120112011
Carr Mtn120251985
Sprucedale120221992

Virginia's Warbler Population Trend in Other States

californiacoloradoidahonevadanew-mexicosouth-dakotautahwyoming

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