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

Hermit Thrush Population Trend in Colorado

All statesForest birds

Hermit Thrush in Colorado has surged: up 277% on the route-weighted index since 1970.

+277%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 →
81Routes 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 ColoradoNotable 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 Colorado: up 277% on the route-weighted index since 1970.

Hermit Thrush Population Forecast in Colorado

If the recent trend holds, Hermit Thrush in Colorado is projected to rise about 41% by 2029 — from 4.6 in 2024 to a central estimate of 6.5 (95% range 4.6–8.4). A 5-year backtest shows a typical error of ±37.2%, with 20% of held-out values landing inside the 95% band.

+41%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 →
6.5Projected 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 →
4.6–8.495% 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 →
±37.2%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 Colorado is projected to rise about 41% by 2029 — from 4.6 in 2024 to a central estimate of 6.5 (95% range 4.6–8.4). A 5-year backtest shows a typical error of ±37.2%, with 20% 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 →
20256.14.28.0
20266.24.38.1
20276.34.48.2
20286.44.58.3
20296.54.68.4

Hermit Thrush Survey Routes in Colorado

Routes recording Hermit Thrush in Colorado.
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 →
Buffalo Park7720231992
Pinos Creek4419901988
Mount Evans3420241996
South Fork3320241994
Haycamp Mesa3220241998
Mcphee Res.2720241996
Baxter Pass2520241994
Cochetopa Pass2520241998
Pinon2420241992
Lake City2220031988
Rollins Pass2220221998
Deadman Rd.2020241992
Dunckley Pas1720241992
Owl Creek Pass1620241998
Lizard Head Pass1620242001
Uncompahgre1520241988
Guanella Pas1520241992
Dolores Riv1420241988
Lake City 21420242016
Weston Pass1420001994
Stillwater Pass1420092005
Nucla1420241999
Como1320241994
Moon Pass1220241998
Lost Lake1020241990

Hermit Thrush Population Trend in Other States

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

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