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

Chestnut-sided Warbler Population Trend in Vermont

All statesForest birds

Chestnut-sided Warbler in Vermont has risen sharply: up 52% on the route-weighted index since 1968.

+52%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 →
26Routes 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 →
59YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Chestnut-sided Warbler 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 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 →

Chestnut-sided Warbler has risen sharply in Vermont: up 52% on the route-weighted index since 1968.

Chestnut-sided Warbler Population Forecast in Vermont

If the recent trend holds, Chestnut-sided Warbler in Vermont is projected to fall about 35% by 2030 — from 16 in 2025 to a central estimate of 10 (95% range 6.3–15). A 5-year backtest shows a typical error of ±34.2%, with 20% of held-out values landing inside the 95% band.

-35%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 →
10Projected 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 →
6.3–1595% 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 →
±34.2%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, Chestnut-sided Warbler in Vermont is projected to fall about 35% by 2030 — from 16 in 2025 to a central estimate of 10 (95% range 6.3–15). A 5-year backtest shows a typical error of ±34.2%, with 20% 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 →
2026106.315
2027106.315
2028106.315
2029106.315
2030106.315

Chestnut-sided Warbler Survey Routes in Vermont

Routes recording Chestnut-sided Warbler 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 →
Stowe3820241988
Landgrove3020251966
Gaysville3020251966
Northfld Fls2920251980
Greensboro2320251967
Shaftsbury2220251966
East Haven2120251966
S Wallingfrd1920221966
St Johnsbury1920251970
Middlesex1920251968
Hardwick1920241966
Waterville1919801968
East Calais1720251966
North Pownal1420251966
S Reading1420241966
Fletcher1320251971
Marlboro1120251966
Post Mills1120251966
Stratton1020251966
W Rutland920251966
Newbury 2920232005
Bristol620251995
Colchester420251986
Newbury320041986
Hinesburg319941966

Chestnut-sided Warbler Population Trend in Other States

alabamaarkansascoloradoconnecticutgeorgiaillinoisindianaiowakansaskentuckymainemarylandmassachusettsmichiganminnesotanevadanew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiopennsylvaniarhode-islandtennesseevirginiawest-virginiawisconsinwyoming

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