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Species · Washington · BBS 2025 Release · 1966–2024

Swainson's Thrush Population Trend in Washington

All statesForest birds

Swainson's Thrush in Washington has declined: down 35% on the route-weighted index since 1970.

-35%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 →
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 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 2029 — from 24 in 2024 to a central estimate of 19 (95% range 8.8–29). A 5-year backtest shows a typical error of ±24%, with 100% of held-out values landing inside the 95% band.

-21%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 →
19Projected 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 →
8.8–2995% 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 →
±24%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 2029 — from 24 in 2024 to a central estimate of 19 (95% range 8.8–29). A 5-year backtest shows a typical error of ±24%, 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 →
2025199.529
2026199.329
2027199.229
2028199.029
2029198.829

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 →
Pe Ell9820231993
Ozette8820241971
Raymond 28420242022
Neilton6519751975
Raymond6520211993
Taholah6420221969
Kendall6420241981
Concrete6420242013
Montesand6120241986
Sullivan Lake 26020242000
Issaquah5819871969
Ilwaco5720241975
Mendota 35420242005
Carnation5020241988
Index4919711968
South Elma4920241975
Vashon Is.4820241995
Mendota4519881977
Index 24120232014
Newhalem4020241968
Port Angeles3920241970
Warm Beach3920171968
Suiattle Riv3820191993
White Chuck3720241992
Twin Lakes3620241983

Swainson's Thrush Population Trend in Other States

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

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