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

American Bittern Population Trend in Vermont

All statesWetland birds

American Bittern in Vermont has held roughly steady: down 2% on the route-weighted index since 1968.

-2%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 →
23Routes 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 American Bittern 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 American Bittern in Vermont. See the full index history below.

American Bittern Population Forecast in Vermont

If the recent trend holds, American Bittern in Vermont is projected to fall about 16% by 2029 — from 0.33 in 2024 to a central estimate of 0.28 (95% range 0.00–0.61). A 5-year backtest shows a typical error of ±105.2%, with 100% of held-out values landing inside the 95% band.

-16%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 →
0.28Projected 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 →
0.00–0.6195% 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 →
±105.2%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, American Bittern in Vermont is projected to fall about 16% by 2029 — from 0.33 in 2024 to a central estimate of 0.28 (95% range 0.00–0.61). A 5-year backtest shows a typical error of ±105.2%, 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 →
20250.280.000.61
20260.280.000.61
20270.280.000.61
20280.280.000.61
20290.280.000.61

American Bittern Survey Routes in Vermont

Routes recording American Bittern 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 →
W Rutland320241967
S Reading220241977
East Calais220231968
Hardwick220071967
Stowe220231999
Marlboro120191978
Stratton120131968
Landgrove119711971
Post Mills120141976
Shaftsbury120001968
S Wallingfrd120211966
St Johnsbury120191991
East Haven120081968
Northfld Fls120162002
Middlesex120182007
Greensboro120241969
Fletcher120191969
Waterville119801980
Hinesburg119891969
Colchester120082007
Grand Isle119951969
Newbury 2120162008
Bristol120132008

American Bittern Population Trend in Other States

alaskacaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaslouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-dakotaohiooklahomaoregonpennsylvaniasouth-carolinasouth-dakotatexasutahvirginiawashingtonwest-virginiawisconsinwyoming

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