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

Townsend's Warbler Population Trend in Washington

All statesForest birds

Townsend's Warbler in Washington has surged: up 129% on the route-weighted index since 1970.

+129%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 →
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 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 129% 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 rise about 13% by 2029 — from 5.6 in 2024 to a central estimate of 6.4 (95% range 3.8–9.0). A 5-year backtest shows a typical error of ±21.7%, with 100% of held-out values landing inside the 95% band.

+13%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 →
6.4Projected 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 →
3.8–9.095% 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 →
±21.7%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 rise about 13% by 2029 — from 5.6 in 2024 to a central estimate of 6.4 (95% range 3.8–9.0). A 5-year backtest shows a typical error of ±21.7%, with 100% of held-out values landing inside the 95% band.19682029
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 →
20256.23.68.8
20266.23.68.8
20276.33.78.9
20286.33.79.0
20296.43.89.0

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 Pass8720241992
Hurricane Rg3620241992
Rimrock2820241968
L Pend O Nwr2120241995
Cusick2120241982
Sullivan Lake 21820242000
Sullivan Lk1819991999
Index 21720232015
Cedar Falls1620141996
Taholah1520221987
No Cascades1420191988
Cloverland1420241993
Twin Lakes1120241986
Leavenworth1120241982
Greenwater1120242015
Cascade Riv1020061988
Mazama1020221993
Ronald920241973
Omak Creek920241996
Glacier820241975
Spring Lake720241986
L. Wenatchee720241993
Kamilche619781972
Packwood620241975
Mt St Helens520241992

Townsend's Warbler Population Trend in Other States

alaskaidahomontanaoregonwyoming

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