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Species · Idaho · BBS 2026 Release · 1966–2025

Townsend's Warbler Population Trend in Idaho

All statesForest birds

Townsend's Warbler in Idaho has surged: up 802% on the route-weighted index since 1972.

+802%Since 1972TrendPercent 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 →
26Routes 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 Townsend's Warbler 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 →

Townsend's Warbler has surged in Idaho: up 802% on the route-weighted index since 1972.

Townsend's Warbler Population Forecast in Idaho

If the recent trend holds, Townsend's Warbler in Idaho is projected to rise about 68% by 2030 — from 4.2 in 2025 to a central estimate of 7.1 (95% range 3.9–10). A 5-year backtest shows a typical error of ±145.3%, with 40% of held-out values landing inside the 95% band.

+68%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 →
7.1Projected 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 →
3.9–1095% 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 →
±145.3%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, Townsend's Warbler in Idaho is projected to rise about 68% by 2030 — from 4.2 in 2025 to a central estimate of 7.1 (95% range 3.9–10). A 5-year backtest shows a typical error of ±145.3%, with 40% 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 →
20266.73.59.9
20276.83.610.0
20286.93.710
20297.03.810
20307.13.910

Townsend's Warbler Survey Routes in Idaho

Routes recording Townsend's Warbler 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 →
Lolo Pass16220191992
Baldy Mountain5120162013
Avery4020251979
Marble Creek3520251988
Mivoden2920251977
Nezperce Nf2419991992
N Fork Cda R2320191993
Golden2120161987
Pierce2120071990
Rochat Divde1420251993
Grangeville1320251986
Coolin920251986
Squirrel719941994
Nezperce520121985
Cascade519841983
Cabarton520231985
Salmon River420251988
Alturas319681968
Burgdorf220251988
Naples120251972
Gifford119911971
Centerville120251983
Joel120112006
Cobalt120102010
Yellow Pine120141991

Townsend's Warbler Population Trend in Other States

alaskamontanaoregonwashingtonwyoming

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