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

Western Tanager Population Trend in Arizona

All statesGeneralists

Western Tanager in Arizona has surged: up 16× on the route-weighted index since 1970.

16×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 →
37Routes 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 Western Tanager 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 →

Western Tanager has surged in Arizona: up 16× on the route-weighted index since 1970.

Western Tanager Population Forecast in Arizona

If the recent trend holds, Western Tanager in Arizona is projected to rise about 116% by 2029 — from 2.1 in 2024 to a central estimate of 4.5 (95% range 1.8–7.2). A 5-year backtest shows a typical error of ±39.4%, with 100% of held-out values landing inside the 95% band.

+116%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 →
4.5Projected 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 →
1.8–7.295% 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 →
±39.4%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, Western Tanager in Arizona is projected to rise about 116% by 2029 — from 2.1 in 2024 to a central estimate of 4.5 (95% range 1.8–7.2). A 5-year backtest shows a typical error of ±39.4%, 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 →
20254.31.67.0
20264.41.77.0
20274.41.77.1
20284.51.87.1
20294.51.87.2

Western Tanager Survey Routes in Arizona

Routes recording Western Tanager 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. Graham4520231995
Flagstaff3520221988
Happy Jack3320241977
Tsaile3220231993
Dry Park2820241992
Alpine2120231993
Prescott1720221974
Sprucedale1720231992
Williams1320191993
Redington1220232022
Sawmill1020141988
Pinetop1020221993
Aztec Peak719781974
Blue719911974
Portal520241975
Pomerene420221971
Rucker320091995
Wikieup320121992
Forest Lakes320241992
House Rock220221971
Round Rock219761970
Sunizona219861970
Tonto Vill.220211992
Carr Mtn220241985
Black Mesa119911988

Western Tanager Population Trend in Other States

alaskacaliforniacoloradoidahomontananebraskanevadanew-mexicooregonsouth-dakotatexasutahwashingtonwyoming

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