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

Marsh Wren Population Trend in Vermont

All statesForest birds

Marsh Wren in Vermont has declined: down 43% on the route-weighted index since 1970.

-43%Since 1970TrendPercent 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 →
8Routes 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 →
48YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Marsh Wren 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 Marsh Wren in Vermont. See the full index history below.

Marsh Wren Population Forecast in Vermont

If the recent trend holds, Marsh Wren in Vermont is projected to rise about 216% by 2029 — from 0.11 in 2024 to a central estimate of 0.35 (95% range 0.00–0.86). A 5-year backtest shows a typical error of ±558.2%, with 100% of held-out values landing inside the 95% band.

+216%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 →
0.35Projected 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 →
0.00–0.8695% 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 →
±558.2%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, Marsh Wren in Vermont is projected to rise about 216% by 2029 — from 0.11 in 2024 to a central estimate of 0.35 (95% range 0.00–0.86). A 5-year backtest shows a typical error of ±558.2%, with 100% of held-out values landing inside the 95% band.19672029
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 →
20250.350.000.87
20260.350.000.87
20270.350.000.86
20280.350.000.86
20290.350.000.86

Marsh Wren Survey Routes in Vermont

Routes recording Marsh Wren 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 →
Hinesburg819941977
Bristol320001995
S Wallingfrd220221973
W Rutland220241979
Landgrove120172017
Post Mills120182018
Colchester120082008
Grand Isle119921967

Marsh Wren Population Trend in Other States

alabamaarizonacaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaslouisianamainemarylandmassachusettsmichiganminnesotamissourimontananebraskanevadanew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiooregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatexasutahvirginiawashingtonwisconsinwyoming

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