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

Black-throated Blue Warbler Population Trend in Vermont

All statesForest birds

Black-throated Blue Warbler in Vermont has surged: up 349% on the route-weighted index since 1968.

+349%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 →
25Routes 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 Black-throated Blue 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 →

Black-throated Blue Warbler has surged in Vermont: up 349% on the route-weighted index since 1968.

Black-throated Blue Warbler Population Forecast in Vermont

If the recent trend holds, Black-throated Blue Warbler in Vermont is projected to rise about 121% by 2029 — from 1.3 in 2024 to a central estimate of 2.9 (95% range 1.7–4.2). A 5-year backtest shows a typical error of ±66.1%, with 60% of held-out values landing inside the 95% band.

+121%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 →
2.9Projected 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 →
1.7–4.295% 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 →
±66.1%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, Black-throated Blue Warbler in Vermont is projected to rise about 121% by 2029 — from 1.3 in 2024 to a central estimate of 2.9 (95% range 1.7–4.2). A 5-year backtest shows a typical error of ±66.1%, with 60% 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 →
20252.81.54.1
20262.81.64.1
20272.91.64.2
20282.91.64.2
20292.91.74.2

Black-throated Blue Warbler Survey Routes in Vermont

Routes recording Black-throated Blue 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 →
Stratton620241966
Marlboro520241967
Gaysville320211966
Northfld Fls320211980
Newbury320031986
Waterville319801968
Colchester319911990
Newbury 2320232008
Stowe320241989
North Pownal220211971
Landgrove220241979
Shaftsbury220231968
St Johnsbury220231970
East Haven220241966
Middlesex220241968
East Calais220241967
Greensboro220231969
S Reading120241966
Post Mills120181975
S Wallingfrd120221974
W Rutland120151987
Hardwick120241968
Fletcher120221999
Hinesburg119931969
Grand Isle119851985

Black-throated Blue Warbler Population Trend in Other States

connecticutgeorgiamainemarylandmassachusettsmichiganminnesotanew-hampshirenew-jerseynew-yorknorth-carolinapennsylvaniarhode-islandtennesseevirginiawest-virginiawisconsin

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