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Species · Idaho · BBS 2026 Release · 1966–2025

Varied Thrush Population Trend in Idaho

All statesForest birds

Varied Thrush in Idaho has edged down: down 19% on the route-weighted index since 1972.

-19%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 →
24Routes 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 →
52YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Varied 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 Varied Thrush in Idaho. See the full index history below.

Varied Thrush Population Forecast in Idaho

If the recent trend holds, Varied Thrush in Idaho is projected to rise about 38% by 2030 — from 1.3 in 2025 to a central estimate of 1.7 (95% range 0.00–3.6). A 5-year backtest shows a typical error of ±101.5%, with 100% of held-out values landing inside the 95% band.

+38%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 →
1.7Projected 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 →
0.00–3.695% 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 →
±101.5%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, Varied Thrush in Idaho is projected to rise about 38% by 2030 — from 1.3 in 2025 to a central estimate of 1.7 (95% range 0.00–3.6). A 5-year backtest shows a typical error of ±101.5%, 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 →
20261.80.003.6
20271.80.003.6
20281.80.003.6
20291.70.003.6
20301.70.003.6

Varied Thrush Survey Routes in Idaho

Routes recording Varied 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 →
Lolo Pass3220191992
Grangeville1920251986
Baldy Mountain1620162013
Avery1520251979
Pierce1020071990
Marble Creek920251988
N Fork Cda R620191993
Cascade419831983
Rochat Divde420241993
Alturas419681968
Coolin320241986
Naples220221972
Nezperce220121968
Golden220161987
Nezperce Nf219991992
Mivoden120251977
Deep Creek119851985
Cape Horn120051997
Centerville120072007
Salmon River120211988
Burgdorf120161988
Cobalt120022002
Yellow Pine120011991
Featherville120071989

Varied Thrush Population Trend in Other States

alaskacaliforniamontanaoregonwashington

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