BirdAnalyst
Species · California · BBS 2026 Release · 1966–2025

Hermit Thrush Population Trend in California

All statesForest birds

Hermit Thrush in California has edged up: up 21% on the route-weighted index since 1970.

+21%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 →
116Routes 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 Hermit Thrush Trends in CaliforniaNotable 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 Thrush in California. See the full index history below.

Hermit Thrush Population Forecast in California

If the recent trend holds, Hermit Thrush in California is projected to rise about 135% by 2030 — from 1.1 in 2025 to a central estimate of 2.5 (95% range 0.94–4.1). A 5-year backtest shows a typical error of ±175.7%, with 0% of held-out values landing inside the 95% band.

+135%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 →
2.5Projected 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 →
0.94–4.195% 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 →
±175.7%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, Hermit Thrush in California is projected to rise about 135% by 2030 — from 1.1 in 2025 to a central estimate of 2.5 (95% range 0.94–4.1). A 5-year backtest shows a typical error of ±175.7%, with 0% 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 →
20262.50.904.1
20272.50.914.1
20282.50.924.1
20292.50.934.1
20302.50.944.1

Hermit Thrush Survey Routes in California

Routes recording Hermit Thrush in California.
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 →
Martins Fy3320091976
Ukiah2820111988
Big Flat2220142002
Navarro2120111972
Medicine Mtn.2020212000
Fairfax1920241975
Ship Mtn.1820171994
Hiouchi1820142002
Dirigio1820141999
Bodega Bay1620211972
Fish Rock1520141968
Waterman Gap1420251972
Holmes1320251969
Offield Mtn1320141973
Westville1120251971
Bartle1120211972
Pescadero1120251992
Lonesome Rdg1120141994
Tionesta1120211997
Goumaz1120111997
Lassen Park1019891972
Johnsville1020251975
Mt Shasta1020191972
Burnt Ranch1020162001
Pilot Creek919961994

Hermit Thrush Population Trend in Other States

alaskaarizonacoloradoconnecticutidahoindianamainemarylandmassachusettsmichiganminnesotamontananevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinaohiooregonpennsylvaniarhode-islandsouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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