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Species · Arizona · BBS 2026 Release · 1966–2025

Olive Warbler Population Trend in Arizona

All statesForest birds

Olive Warbler in Arizona has surged: up 377% on the route-weighted index since 1979.

+377%Since 1979TrendPercent 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 →
13Routes 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 →
42YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Olive 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 →

Olive Warbler has surged in Arizona: up 377% on the route-weighted index since 1979.

Olive Warbler Population Forecast in Arizona

If the recent trend holds, Olive Warbler in Arizona is projected to fall about 44% by 2030 — from 0.71 in 2025 to a central estimate of 0.40 (95% range 0.13–0.67). A 5-year backtest shows a typical error of ±67.4%, with 40% of held-out values landing inside the 95% band.

-44%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 →
0.40Projected 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 →
0.13–0.6795% 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 →
±67.4%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, Olive Warbler in Arizona is projected to fall about 44% by 2030 — from 0.71 in 2025 to a central estimate of 0.40 (95% range 0.13–0.67). A 5-year backtest shows a typical error of ±67.4%, with 40% of held-out values landing inside the 95% band.19772030
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 →
20260.370.100.64
20270.380.110.65
20280.380.120.65
20290.390.120.66
20300.400.130.67

Olive Warbler Survey Routes in Arizona

Routes recording Olive 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. Graham1320251995
Tonto Vill.720252001
Portal420251977
Forest Lakes320212001
Prescott320181992
Pinetop220222021
Carr Mtn220181989
Alpine220252002
Williams220012001
Sprucedale220252005
Rucker120042004
Happy Jack120252001
Aztec Peak119771977

Olive Warbler Population Trend in Other States

new-mexico

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