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

Hermit Thrush Population Trend in Washington

All statesForest birds

Hermit Thrush in Washington has surged: up 122% on the route-weighted index since 1970.

+122%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 →
51Routes 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 Hermit 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 →

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 →

Hermit Thrush has surged in Washington: up 122% on the route-weighted index since 1970.

Hermit Thrush Population Forecast in Washington

If the recent trend holds, Hermit Thrush in Washington is projected to stay roughly flat through 2029, near 5.0 (95% range 3.5–6.5). A 5-year backtest shows a typical error of ±26.3%, with 80% of held-out values landing inside the 95% band.

+2%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 →
5.0Projected 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 →
3.5–6.595% 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 →
±26.3%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, Hermit Thrush in Washington is projected to stay roughly flat through 2029, near 5.0 (95% range 3.5–6.5). A 5-year backtest shows a typical error of ±26.3%, with 80% 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 →
20254.73.26.2
20264.83.36.3
20274.93.46.3
20284.93.56.4
20295.03.56.5

Hermit Thrush Survey Routes in Washington

Routes recording Hermit 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 →
Blewett Pass6920241992
Mt. Adams4020241993
Cloverland3220241996
E. Mt. Adams2720241995
Twin Lakes2319931986
Ronald2320241973
Glacier1420241975
Rimrock1320241968
Sullivan Lake 21120242000
Spring Lake1120241985
Mt Rainier1020211990
Laurier1020222005
Greenwater1020242015
No Cascades820191988
Hurricane Rg820241992
Mt St Helens820241992
Index819971997
Twisp720151985
Leavenworth720241984
Cusick420221988
Nighthawk420001992
Sullivan Lk419991999
L. Wenatchee420241993
Mendota319881978
Packwood320241976

Hermit Thrush Population Trend in Other States

alaskaarizonacaliforniacoloradoconnecticutidahomainemarylandmassachusettsmichiganminnesotamontananevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinaohiooregonpennsylvaniarhode-islandsouth-dakotatennesseetexasutahvermontvirginiawest-virginiawisconsinwyoming

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