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Species · Idaho · BBS 2026 Release · 1966–2025

Hermit Thrush Population Trend in Idaho

All statesForest birds

Hermit Thrush in Idaho has surged: up 103% on the route-weighted index since 1971.

+103%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 →
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 IdahoNotable 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 Idaho: up 103% on the route-weighted index since 1971.

Hermit Thrush Population Forecast in Idaho

If the recent trend holds, Hermit Thrush in Idaho is projected to fall about 45% by 2030 — from 1.7 in 2025 to a central estimate of 0.91 (95% range 0.00–1.9). A 5-year backtest shows a typical error of ±20.5%, with 100% of held-out values landing inside the 95% band.

-45%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 →
0.91Projected 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 →
0.00–1.995% 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 →
±20.5%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 45% by 2030 — from 1.7 in 2025 to a central estimate of 0.91 (95% range 0.00–1.9). A 5-year backtest shows a typical error of ±20.5%, with 100% 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 →
20260.920.001.9
20270.910.001.9
20280.910.001.9
20290.910.001.9
20300.910.001.9

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
Avery1320252012
Cobalt920251989
Mivoden820192000
Golden819871987
Cascade819841983
Silver City820251989
Magic Mtn720251989
Challis620251975
Rochat Divde520241994
Pierce520051994
Grangeville420251986
Yellow Pine420161989
Gifford319711971
Lolo Pass320191995
Salmon River320251989
Sawtooth Cty320141988
Baker220131974
Cape Horn220241972
Kyle Canyon220222022
Coolin220251989
Baldy Mountain220162016
Twin Buttes220242024
Sunbeam220251994

Hermit Thrush Population Trend in Other States

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

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