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Species · Idaho · BBS 2025 Release · 1966–2024

Swainson's Thrush Population Trend in Idaho

All statesForest birds

Swainson's Thrush in Idaho has surged: up 133% on the route-weighted index since 1971.

+133%Since 1971TrendPercent 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 →
38Routes 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 →
55YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Swainson's 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 →

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 →

Swainson's Thrush has surged in Idaho: up 133% on the route-weighted index since 1971.

Swainson's Thrush Population Forecast in Idaho

If the recent trend holds, Swainson's Thrush in Idaho is projected to rise about 122% by 2029 — from 5.4 in 2024 to a central estimate of 12 (95% range 7.6–16). A 5-year backtest shows a typical error of ±43.7%, with 60% of held-out values landing inside the 95% band.

+122%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 →
12Projected 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 →
7.6–1695% 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 →
±43.7%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 Idaho is projected to rise about 122% by 2029 — from 5.4 in 2024 to a central estimate of 12 (95% range 7.6–16). A 5-year backtest shows a typical error of ±43.7%, with 60% 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 →
2025117.116
2026127.216
2027127.416
2028127.516
2029127.616

Swainson's Thrush Survey Routes in Idaho

Routes recording Swainson's 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 Pass9620191992
Avery6320231979
Rochat Divde6120231993
Pierce5320071990
Grangeville4820241986
Deep Creek4419851985
Marble Creek3920231988
N Fork Cda R3620191993
Baldy Mountain3320162013
Golden3020161987
Naples2620241972
Mivoden2620231977
Cabarton1820231985
Sunbeam1620191994
Cape Horn1320241986
Centerville1220191972
Coolin1220241986
Featherville1220241990
Cascade1119841983
Cobalt1020241998
Silver City1020141993
Alturas919871968
Nezperce720121968
Salmon River720211988
Nezperce Nf719991992

Swainson's Thrush Population Trend in Other States

alaskaarizonacaliforniacoloradoconnecticutillinoismainemarylandmassachusettsmichiganminnesotamontananebraskanevadanew-hampshirenew-mexiconew-yorknorth-carolinaoregonpennsylvaniasouth-dakotautahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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