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

Black-throated Green Warbler Population Trend in Vermont

All statesForest birds

Black-throated Green Warbler in Vermont has surged: up 238% on the route-weighted index since 1968.

+238%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 →
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 Green 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 Green Warbler has surged in Vermont: up 238% on the route-weighted index since 1968.

Black-throated Green Warbler Population Forecast in Vermont

If the recent trend holds, Black-throated Green Warbler in Vermont is projected to rise about 31% by 2029 — from 3.5 in 2024 to a central estimate of 4.6 (95% range 2.7–6.5). A 5-year backtest shows a typical error of ±72.7%, with 40% of held-out values landing inside the 95% band.

+31%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 →
4.6Projected 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 →
2.7–6.595% 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 →
±72.7%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, Black-throated Green Warbler in Vermont is projected to rise about 31% by 2029 — from 3.5 in 2024 to a central estimate of 4.6 (95% range 2.7–6.5). A 5-year backtest shows a typical error of ±72.7%, with 40% 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 →
20254.42.56.3
20264.42.56.3
20274.52.66.4
20284.52.66.4
20294.62.76.5

Black-throated Green Warbler Survey Routes in Vermont

Routes recording Black-throated Green 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 →
Stowe1320241989
East Calais920241966
Marlboro820241966
Stratton820241966
Middlesex820241968
Hardwick820161966
Landgrove720241966
Northfld Fls720211980
Waterville619801969
Gaysville520191966
Newbury420041987
East Haven320241967
Newbury 2320222005
St Johnsbury220241970
Bristol219981998
North Pownal120211967
S Reading120241966
Post Mills120241969
Shaftsbury120241967
S Wallingfrd120221967
W Rutland120241974
Greensboro120221969
Fletcher120241983
Hinesburg119901971
Colchester120071988

Black-throated Green Warbler Population Trend in Other States

alabamaarkansasconnecticutgeorgiaindianakentuckymainemarylandmassachusettsmichiganminnesotamissourinew-hampshirenew-jerseynew-yorknorth-carolinaohiooklahomapennsylvaniarhode-islandsouth-carolinatennesseevirginiawest-virginiawisconsin

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