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Species · BCR 4 · BBS 2025 Release · 1966–2024

Varied Thrush In BCR 4

All regionsBCR 4Forest birds

Varied Thrush in BCR 4 has edged down: down 14% on the route-weighted index since 1976.

-14%Since 1976TrendPercent 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 →
67Routes 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 →
47YearsYears 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 →

No notable trend signals for Varied Thrush in BCR 4. See the full index history below.

Varied Thrush In BCR 4 Population Forecast

If the recent trend holds, Varied Thrush in BCR 4 is projected to rise about 40% by 2029 — from 6.9 in 2024 to a central estimate of 9.7 (95% range 3.0–16). A 5-year backtest shows a typical error of ±42.2%, with 100% of held-out values landing inside the 95% band.

+40%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 →
9.7Projected 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 →
3.0–1695% 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 →
±42.2%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, Varied Thrush in BCR 4 is projected to rise about 40% by 2029 — from 6.9 in 2024 to a central estimate of 9.7 (95% range 3.0–16). A 5-year backtest shows a typical error of ±42.2%, 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 →
2025103.417
2026103.317
20279.93.217
20289.83.117
20299.73.016

Routes In BCR 4

Routes recording Varied Thrush in BCR 4.
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 →
TatalinaALASKA402019
HomerALASKA371982
PetersvilleALASKA332024
Seven LakesALASKA282023
Unalakleet RiverALASKA272024
Chena Hot Spring 2ALASKA262024
Bear CreekALASKA251991
Swan Lake RdALASKA252023
L SalchaALASKA232023
ChickenALASKA202024
WasillaALASKA201983
Mt. FairplayALASKA202024
RubyALASKA202024
MatanuskaALASKA191983
Goose BayALASKA181982
Kobuk River (Short)ALASKA151992
Skilak LakeALASKA141985
Koyukuk Riv.ALASKA142001
Anvik RiverALASKA132024
Chatanika RALASKA122023
Chena RiverALASKA121988
Nabesna RoadALASKA122024
SlanaALASKA112024
Ft. RichrdsnALASKA102023
LivengoodALASKA92021

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