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

Western Tanager Population Trend in Alaska

All statesGeneralists

Western Tanager in Alaska has surged: up 208% on the route-weighted index since 1990.

+208%Since 1990TrendPercent 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 →
10Routes 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 →
35YearsYears 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 AlaskaNotable 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 Alaska: up 208% on the route-weighted index since 1990.

Western Tanager Population Forecast in Alaska

If the recent trend holds, Western Tanager in Alaska is projected to fall about 38% by 2029 — from 0.24 in 2024 to a central estimate of 0.15 (95% range 0.04–0.26). A 5-year backtest shows a typical error of ±32.9%, with 80% of held-out values landing inside the 95% band.

-38%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 →
0.15Projected 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 →
0.04–0.2695% 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 →
±32.9%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 Alaska is projected to fall about 38% by 2029 — from 0.24 in 2024 to a central estimate of 0.15 (95% range 0.04–0.26). A 5-year backtest shows a typical error of ±32.9%, with 80% of held-out values landing inside the 95% band.19882029
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 →
20250.140.030.25
20260.140.030.25
20270.140.030.25
20280.140.030.26
20290.150.040.26

Western Tanager Survey Routes in Alaska

Routes recording Western Tanager in Alaska.
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 →
Skagway520241994
Haines520241994
Stikine River420241998
Hyder420091995
Juneau220242024
Mitkof Isle220231988
Zimovia Strt120041990
Harlequin L.120072007
Hoonah120032003
Thorne Bay 2120172017

Western Tanager Population Trend in Other States

arizonacaliforniacoloradoidahomontananebraskanevadanew-mexicooregonsouth-dakotatexasutahwashingtonwyoming

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