BirdAnalyst
Species · Vermont · BBS 2026 Release · 1966–2025

Brown Thrasher Population Trend in Vermont

All statesForest birds

Brown Thrasher in Vermont has fallen sharply: down 69% on the route-weighted index since 1968.

-69%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 →
24Routes 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 →
58YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Brown Thrasher 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 →

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 →

Brown Thrasher has fallen sharply in Vermont: down 69% on the route-weighted index since 1968.

Brown Thrasher Population Forecast in Vermont

If the recent trend holds, Brown Thrasher in Vermont is projected to fall about 100% by 2030 — from 0.61 in 2025 to a central estimate of 0.00 (95% range 0.00–0.74). A 5-year backtest shows a typical error of ±175.5%, with 80% of held-out values landing inside the 95% band.

-100%Change by 2030TrendPercent 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 →
0.00Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.7495% 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 →
±175.5%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, Brown Thrasher in Vermont is projected to fall about 100% by 2030 — from 0.61 in 2025 to a central estimate of 0.00 (95% range 0.00–0.74). A 5-year backtest shows a typical error of ±175.5%, with 80% of held-out values landing inside the 95% band.19662030
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 →
20260.000.000.74
20270.000.000.74
20280.000.000.74
20290.000.000.74
20300.000.000.74

Brown Thrasher Survey Routes in Vermont

Routes recording Brown Thrasher 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 →
North Pownal420251966
Waterville319801967
East Haven220251966
Hardwick220111968
Grand Isle220251967
Marlboro119911966
Stratton119981973
Landgrove120251966
S Reading120171966
Gaysville120061966
Post Mills120251966
Shaftsbury120251966
S Wallingfrd120191966
W Rutland120191967
St Johnsbury120181970
Northfld Fls119931980
Middlesex119861971
East Calais119981969
Newbury119951995
Greensboro120151968
Fletcher120241968
Hinesburg119921966
Colchester120222013
Bristol120091996

Brown Thrasher Population Trend in Other States

alabamaarkansascoloradoconnecticutdelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasvirginiawest-virginiawisconsinwyoming

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.