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Species · Arizona · BBS 2025 Release · 1966–2024

Red-faced Warbler Population Trend in Arizona

All statesForest birds

Red-faced Warbler in Arizona has surged: up 402% on the route-weighted index since 1970.

+402%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 →
15Routes 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 Red-faced 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 →

Red-faced Warbler has surged in Arizona: up 402% on the route-weighted index since 1970.

Red-faced Warbler Population Forecast in Arizona

If the recent trend holds, Red-faced Warbler in Arizona is projected to rise about 183% by 2029 — from 0.31 in 2024 to a central estimate of 0.89 (95% range 0.00–2.2). A 5-year backtest shows a typical error of ±56.6%, with 100% of held-out values landing inside the 95% band.

+183%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 →
0.89Projected 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 →
0.00–2.295% 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 →
±56.6%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, Red-faced Warbler in Arizona is projected to rise about 183% by 2029 — from 0.31 in 2024 to a central estimate of 0.89 (95% range 0.00–2.2). A 5-year backtest shows a typical error of ±56.6%, 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 →
20250.910.002.2
20260.900.002.2
20270.900.002.2
20280.890.002.2
20290.890.002.2

Red-faced Warbler Survey Routes in Arizona

Routes recording Red-faced 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 →
Mt. Graham4420231995
Prescott1620221975
Happy Jack820241977
Flagstaff619881988
Portal320241975
Alpine320231994
Rucker220041995
Tonto Vill.120212003
Pinetop120212021
Carr Mtn120171988
Mormon Lake119741968
Aztec Peak119781974
Blue119901974
Williams120182001
Sprucedale120211996

Red-faced Warbler Population Trend in Other States

new-mexico

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