BirdAnalyst
Species · BCR 15 · BBS 2025 Release · 1966–2024

Hermit Thrush In Sierra Nevada

All regionsSierra NevadaForest birds

Hermit Thrush in Sierra Nevada has fallen sharply: down 50% on the route-weighted index since 1972.

-50%Since 1972TrendPercent 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 →
36Routes In RegionSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
54YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable SignalsNotable 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 declinecomputed 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 fallen sharply in Sierra Nevada: down 50% on the route-weighted index since 1972.

Hermit Thrush In Sierra Nevada Population Forecast

If the recent trend holds, Hermit Thrush in Sierra Nevada is projected to rise about 167% by 2029 — from 1.0 in 2024 to a central estimate of 2.7 (95% range 0.65–4.7). A 5-year backtest shows a typical error of ±81%, with 80% of held-out values landing inside the 95% band.

+167%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 →
2.7Projected 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 →
0.65–4.795% 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 →
±81%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 Sierra Nevada is projected to rise about 167% by 2029 — from 1.0 in 2024 to a central estimate of 2.7 (95% range 0.65–4.7). A 5-year backtest shows a typical error of ±81%, with 80% 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 →
20252.80.754.8
20262.70.734.8
20272.70.704.7
20282.70.674.7
20292.70.654.7

Routes In Sierra Nevada

Routes recording Hermit Thrush in Sierra Nevada.
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 →
GoumazCALIFORNIA112011
Lassen ParkCALIFORNIA101989
JohnsvilleCALIFORNIA82024
Little TruckeeCALIFORNIA82023
Tahoe NfCALIFORNIA61994
LumberyardCALIFORNIA52024
ChesterCALIFORNIA52017
StrawberryCALIFORNIA52019
DardanelleCALIFORNIA42019
DownievilleCALIFORNIA32021
Forest HillCALIFORNIA32019
Pine MountainCALIFORNIA32017
Silver CityCALIFORNIA22013
Kings CanyonCALIFORNIA21988
Tuolumne GroveCALIFORNIA22023
Butte MeadowCALIFORNIA22014
Hat CreekCALIFORNIA22018
LakeshoreCALIFORNIA22011
Chaos CraterCALIFORNIA22019
Meadow ValleyCALIFORNIA22024
WawonaCALIFORNIA22022
ChilcootCALIFORNIA22024
Forest Hill 2CALIFORNIA22005
Eagle LakeCALIFORNIA12022
WestvilleCALIFORNIA12024

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