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

Townsend's Warbler Population Trend in Washington

All statesForest birds

Townsend's Warbler in Washington has surged: up 154% on the route-weighted index since 1970.

+154%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 →
69Routes 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 →
57YearsYears 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 WashingtonNotable 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 Washington: up 154% on the route-weighted index since 1970.

Townsend's Warbler Population Forecast in Washington

If the recent trend holds, Townsend's Warbler in Washington is projected to stay roughly flat through 2030, near 6.5 (95% range 3.9–9.0). A 5-year backtest shows a typical error of ±16.4%, with 100% of held-out values landing inside the 95% band.

+2%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 →
6.5Projected 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 →
3.9–9.095% 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 →
±16.4%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, Townsend's Warbler in Washington is projected to stay roughly flat through 2030, near 6.5 (95% range 3.9–9.0). A 5-year backtest shows a typical error of ±16.4%, with 100% 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 →
20266.23.78.8
20276.33.78.9
20286.33.88.9
20296.43.89.0
20306.53.99.0

Townsend's Warbler Survey Routes in Washington

Routes recording Townsend's Warbler in Washington.
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 →
Blewett Pass6320251992
Rimrock3720251968
E. Mt. Adams3220251996
Hurricane Rg3120251992
Mt. Adams2520251994
L Pend O Nwr2120241995
Sullivan Lake 22120252000
Sullivan Lk1819991999
Index 21720232015
Cedar Falls1620141996
Taholah1520221987
No Cascades1420191988
Cusick1420251982
Twin Lakes1220251986
Ronald1120251973
Leavenworth1120241982
Packwood1120251975
Cloverland1120251993
Greenwater1120252015
Cascade Riv1020061988
Mazama1020221993
Omak Creek920241996
Glacier820241975
Kamilche619781972
Concrete620252013

Townsend's Warbler Population Trend in Other States

alaskaidahomontanaoregonwyoming

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