BirdAnalyst
Species · Idaho · BBS 2026 Release · 1966–2025

Western Tanager Population Trend in Idaho

All statesForest birds

Western Tanager in Idaho has surged: up 402% on the route-weighted index since 1971.

+402%Since 1971TrendPercent 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 →
60Routes 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 IdahoNotable 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 Idaho: up 402% on the route-weighted index since 1971.

Western Tanager Population Forecast in Idaho

If the recent trend holds, Western Tanager in Idaho is projected to stay roughly flat through 2030, near 9.9 (95% range 7.0–13). A 5-year backtest shows a typical error of ±20.6%, with 80% of held-out values landing inside the 95% band.

-5%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 →
9.9Projected 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 →
7.0–1395% 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 →
±20.6%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, Western Tanager in Idaho is projected to stay roughly flat through 2030, near 9.9 (95% range 7.0–13). A 5-year backtest shows a typical error of ±20.6%, with 80% of held-out values landing inside the 95% band.19682030
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 →
20269.36.512
20279.56.612
20289.66.713
20299.86.913
20309.97.013

Western Tanager Survey Routes in Idaho

Routes recording Western Tanager in Idaho.
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 →
Cascade5419841968
Cobalt4720251989
Deep Creek4419851985
Coolin4020251986
Mivoden3220251977
Grangeville3120251986
Pierce2820071990
Cabarton2520241985
Marble Creek2420251988
Lolo Pass2320191992
Avery2220251979
Salmon River2220251988
Silver City2120251989
N Fork Cda R1820191993
Cape Horn1720251986
Yellow Pine1520161989
Sunbeam1520251994
Rochat Divde1420251993
Sawtooth Cty1320141988
Centerville1220251972
Baldy Mountain1220162013
Sawtooth City 21220252015
Naples1020251975
Challis1020251976
Squirrel1020251971

Western Tanager Population Trend in Other States

alaskaarizonacaliforniacoloradomontananebraskanevadanew-mexicooregonsouth-dakotatexasutahwashingtonwyoming

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