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Species · Washington · BBS 2026 Release · 1966–2025

Swainson's Thrush Population Trend in Washington

All statesForest birds

Swainson's Thrush in Washington has declined: down 32% on the route-weighted index since 1970.

-32%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 →
82Routes 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 Swainson's Thrush 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 →

No notable trend signals for Swainson's Thrush in Washington. See the full index history below.

Swainson's Thrush Population Forecast in Washington

If the recent trend holds, Swainson's Thrush in Washington is projected to fall about 21% by 2030 — from 24 in 2025 to a central estimate of 19 (95% range 9.0–29). A 5-year backtest shows a typical error of ±21.8%, with 100% of held-out values landing inside the 95% band.

-21%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 →
19Projected 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 →
9.0–2995% 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 →
±21.8%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, Swainson's Thrush in Washington is projected to fall about 21% by 2030 — from 24 in 2025 to a central estimate of 19 (95% range 9.0–29). A 5-year backtest shows a typical error of ±21.8%, 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 →
2026199.729
2027199.529
2028199.429
2029199.229
2030199.029

Swainson's Thrush Survey Routes in Washington

Routes recording Swainson's Thrush 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 →
Ozette9620251971
Raymond 28420242022
Mendota 38320252005
Kendall7820251981
Neilton6519751975
Raymond6520211993
Taholah6420221969
Pe Ell6220251993
Montesand6120241986
Ilwaco5920251975
Issaquah5819871969
Cusick5620251982
Concrete5520252013
Newhalem5320251968
Index4919711968
South Elma4920241975
Sullivan Lake 24620252000
Mendota4519881977
L. Wenatchee4520251993
Rainier4520251993
Twin Lakes4220251983
Index 24120232014
Vashon Is.4120251995
Warm Beach3920171968
Suiattle Riv3820191993

Swainson's Thrush Population Trend in Other States

alaskaarizonacaliforniacoloradoconnecticutidahoillinoismainemarylandmassachusettsmichiganminnesotamontananebraskanevadanew-hampshirenew-mexiconew-yorknorth-carolinaoregonpennsylvaniasouth-dakotautahvermontvirginiawest-virginiawisconsinwyoming

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