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Species · BCR 2 · BBS 2025 Release · 1966–2024

Swainson's Thrush In BCR 2

All regionsBCR 2Forest birds

Swainson's Thrush in BCR 2 has fallen sharply: down 59% on the route-weighted index since 1994.

-59%Since 1994TrendPercent 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 →
7Routes 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 →
29YearsYears 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 →

Swainson's Thrush has fallen sharply in BCR 2: down 59% on the route-weighted index since 1994.

Forecast

If the recent trend holds, Swainson's Thrush in BCR 2 is projected to rise about 16× by 2029 — from 0.33 in 2024 to a central estimate of 5.2 (95% range 0.00–13). A 5-year backtest shows a typical error of ±1523.5%, with 100% of held-out values landing inside the 95% band.

16×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 →
5.2Projected 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 →
0.00–1395% 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 →
±1523.5%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, Swainson's Thrush in BCR 2 is projected to rise about 16× by 2029 — from 0.33 in 2024 to a central estimate of 5.2 (95% range 0.00–13). A 5-year backtest shows a typical error of ±1523.5%, with 100% of held-out values landing inside the 95% band.19842029
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 →
20255.10.0013
20265.10.0013
20275.20.0013
20285.20.0013
20295.20.0013

Routes In BCR 2

Routes recording Swainson's Thrush in BCR 2.
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 →
DillinghamALASKA502019
Katmai N.P.ALASKA462022
Dillingham (Short)ALASKA271984
King SalmonALASKA32024
Gweek RiverALASKA32002
Cape NomeALASKA12023
Kanektok RivALASKA11995

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