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

Hermit Thrush Population Trend in Idaho

All statesForest birds

Hermit Thrush in Idaho has increased: up 47% on the route-weighted index since 1971.

+47%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 →
38Routes 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 →
55YearsYears 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 IdahoNotable 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 Idaho. See the full index history below.

Hermit Thrush Population Forecast in Idaho

If the recent trend holds, Hermit Thrush in Idaho is projected to fall about 18% by 2029 — from 1.0 in 2024 to a central estimate of 0.82 (95% range 0.00–1.8). A 5-year backtest shows a typical error of ±17.6%, with 100% of held-out values landing inside the 95% band.

-18%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 →
0.82Projected 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 →
0.00–1.895% 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 →
±17.6%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 Idaho is projected to fall about 18% by 2029 — from 1.0 in 2024 to a central estimate of 0.82 (95% range 0.00–1.8). A 5-year backtest shows a typical error of ±17.6%, 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 →
20250.840.001.8
20260.830.001.8
20270.830.001.8
20280.820.001.8
20290.820.001.8

Hermit Thrush Survey Routes in Idaho

Routes recording Hermit Thrush in Idaho.
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 →
Deep Creek2019851985
Alturas1819871968
Magic Mtn1020241989
Mivoden820192000
Golden819871987
Cascade819841983
Cobalt820151989
Grangeville620241986
Pierce520051994
Burgdorf420161988
Yellow Pine420161989
Gifford319711971
Lolo Pass320191995
Triangle320211989
Sawtooth City 2320222015
Salmon River320211989
Sawtooth Cty320141988
Baker220131974
Cape Horn220241972
Kyle Canyon220222022
Centerville220191983
Baldy Mountain220162016
Twin Buttes220242024
Sunbeam220181994
Featherville220161989

Hermit Thrush Population Trend in Other States

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

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