BirdAnalyst
Species · Vermont · BBS 2025 Release · 1966–2024

Swainson's Thrush Population Trend in Vermont

All statesForest birds

Swainson's Thrush in Vermont has increased: up 26% on the route-weighted index since 1968.

+26%Since 1968TrendPercent 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 →
16Routes 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 Swainson's Thrush Trends in VermontNotable 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 Swainson's Thrush in Vermont. See the full index history below.

Swainson's Thrush Population Forecast in Vermont

If the recent trend holds, Swainson's Thrush in Vermont is projected to fall about 23% by 2029 — from 0.28 in 2024 to a central estimate of 0.21 (95% range 0.00–0.55). A 5-year backtest shows a typical error of ±147.7%, with 100% of held-out values landing inside the 95% band.

-23%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 →
0.21Projected 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 →
0.00–0.5595% 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 →
±147.7%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 Vermont is projected to fall about 23% by 2029 — from 0.28 in 2024 to a central estimate of 0.21 (95% range 0.00–0.55). A 5-year backtest shows a typical error of ±147.7%, with 100% of held-out values landing inside the 95% band.19662029
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 →
20250.220.000.55
20260.220.000.55
20270.210.000.55
20280.210.000.55
20290.210.000.55

Swainson's Thrush Survey Routes in Vermont

Routes recording Swainson's Thrush in Vermont.
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 →
Middlesex319861968
Stratton220241966
Landgrove220241988
Post Mills219761975
St Johnsbury219931970
Marlboro119711971
S Reading119861968
East Haven120231968
Northfld Fls119951980
East Calais119871966
Hardwick119911982
Greensboro120061999
Waterville119801967
Hinesburg119831983
Newbury 2120232023
Stowe120241991

Swainson's Thrush Population Trend in Other States

alaskaarizonacaliforniacoloradoconnecticutidahoillinoismainemarylandmassachusettsmichiganminnesotamontananebraskanevadanew-hampshirenew-mexiconew-yorknorth-carolinaoregonpennsylvaniasouth-dakotautahvirginiawashingtonwest-virginiawisconsinwyoming

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