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Species · Alaska · BBS 2025 Release · 1966–2024

Varied Thrush Population Trend in Alaska

All statesForest birds

Varied Thrush in Alaska has surged: up 143% on the route-weighted index since 1973.

+143%Since 1973TrendPercent 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 →
119Routes 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 →
50YearsYears 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 AlaskaNotable 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 →

Varied Thrush has surged in Alaska: up 143% on the route-weighted index since 1973.

Varied Thrush Population Forecast in Alaska

If the recent trend holds, Varied Thrush in Alaska is projected to rise about 29% by 2029 — from 19 in 2024 to a central estimate of 24 (95% range 15–34). A 5-year backtest shows a typical error of ±28.1%, with 100% of held-out values landing inside the 95% band.

+29%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 →
24Projected 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 →
15–3495% 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 →
±28.1%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 Alaska is projected to rise about 29% by 2029 — from 19 in 2024 to a central estimate of 24 (95% range 15–34). A 5-year backtest shows a typical error of ±28.1%, 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 →
2025241433
2026241433
2027241433
2028241534
2029241534

Varied Thrush Survey Routes in Alaska

Routes recording Varied Thrush in Alaska.
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 →
Chichagof Is15520241994
Hoonah14520241993
Copper River9820111993
Seward9519921982
Yakutat (Short)9419841984
Kuiu Island9320102004
Petersburg7919871987
Stikine River6920241998
Harlequin L.5920241993
Hyder5920091994
Chiniak5320241985
Tupuknuk5219951995
Sitka (Short)5019921984
Mitkof Isle4920241988
Hope4720241985
Whale Pass4620241997
Craig4520241983
Dillingham4520191993
Thorne Bay 24320242013
Zimovia Strt4020241988
Tatalina4020191995
Moose Pass3919921983
Homer3719821977
Thorne Bay3620121989
Petersville3320241986

Varied Thrush Population Trend in Other States

californiaidahomontanaoregonwashington

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