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

Hermit Warbler Population Trend in Washington

All statesForest birds

Hermit Warbler in Washington has held roughly steady: up 1% on the route-weighted index since 1971.

+1%Since 1971TrendPercent 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 →
27Routes 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 →
51YearsYears 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 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 →

No notable trend signals for Hermit Warbler in Washington. See the full index history below.

Hermit Warbler Population Forecast in Washington

If the recent trend holds, Hermit Warbler in Washington is projected to fall about 20% by 2029 — from 1.5 in 2024 to a central estimate of 1.2 (95% range 0.35–2.1). A 5-year backtest shows a typical error of ±32.9%, with 100% of held-out values landing inside the 95% band.

-20%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 →
1.2Projected 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 →
0.35–2.195% 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 →
±32.9%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 Warbler in Washington is projected to fall about 20% by 2029 — from 1.5 in 2024 to a central estimate of 1.2 (95% range 0.35–2.1). A 5-year backtest shows a typical error of ±32.9%, with 100% of held-out values landing inside the 95% band.19692029
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 →
20251.20.302.0
20261.20.312.0
20271.20.332.0
20281.20.342.0
20291.20.352.1

Hermit Warbler Survey Routes in Washington

Routes recording Hermit 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 →
Mt. Adams4720241993
E. Mt. Adams3120241995
Suiattle Riv1520192017
Cougar1220231969
Mt Rainier520151991
Raymond 2420242022
South Elma419751975
Kamilche320221984
Deception219981998
Mendota 2220001989
Bunker Hill220242016
Ronald219971978
Ilwaco219781975
Mt St Helens220242013
Pe Ell220221994
Montesand119901990
Taholah120092009
Mcchord120151996
Rimrock119761976
Snowden120221984
Mendota119831983
Packwood120151975
White Chuck119991999
Carlton119981997
Raymond119931993

Hermit Warbler Population Trend in Other States

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