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

Virginia's Warbler Population Trend in Arizona

All statesForest birds

Virginia's Warbler in Arizona has surged: up 109% on the route-weighted index since 1970.

+109%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 →
54YearsYears 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 109% 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 rise about 617% by 2029 — from 0.11 in 2024 to a central estimate of 0.82 (95% range 0.00–4.2). A 5-year backtest shows a typical error of ±284.1%, with 100% of held-out values landing inside the 95% band.

+617%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 →
0.82Projected 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 →
0.00–4.295% 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 →
±284.1%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, Virginia's Warbler in Arizona is projected to rise about 617% by 2029 — from 0.11 in 2024 to a central estimate of 0.82 (95% range 0.00–4.2). A 5-year backtest shows a typical error of ±284.1%, with 100% 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 →
20250.980.004.4
20260.940.004.4
20270.900.004.3
20280.860.004.3
20290.820.004.2

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 →
Prescott1920221974
Pomerene1720041995
Aztec Peak1019781974
Mt. Graham1020231995
Tonto Vill.720211994
Skull Valley320111996
Blue219911975
Sunizona219961968
Forest Lakes220241994
House Rock119741974
Black Mesa119921992
Portal120241978
Rucker119971996
Flagstaff119911990
Sawmill120142005
Mormon Lake119751968
Dry Park120042000
Williams120182001
Maine119971997
Alpine120181996
Seligman120112011
Happy Jack120221999
Carr Mtn120241985
Sprucedale120221992

Virginia's Warbler Population Trend in Other States

californiacoloradoidahonevadanew-mexicosouth-dakotautahwyoming

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22.