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

Marsh Wren Population Trend in Maine

All statesForest birds

Marsh Wren in Maine has held roughly steady: down 8% on the route-weighted index since 1987.

-8%Since 1987TrendPercent 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 →
9Routes 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 →
18YearsYears 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 MaineNotable 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 Maine. See the full index history below.

Marsh Wren Population Forecast in Maine

If the recent trend holds, Marsh Wren in Maine is projected to stay roughly flat through 2022, near 0.05 (95% range 0.00–0.10). A 5-year backtest shows a typical error of ±61.9%, with 80% of held-out values landing inside the 95% band.

n/aChange by 2022TrendPercent 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 →
0.05Projected 2022 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.1095% 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 →
±61.9%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 Maine is projected to stay roughly flat through 2022, near 0.05 (95% range 0.00–0.10). A 5-year backtest shows a typical error of ±61.9%, with 80% of held-out values landing inside the 95% band.19812022
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 →
20180.050.000.10
20190.050.000.10
20200.050.000.10
20210.050.000.10
20220.050.000.10

Marsh Wren Survey Routes in Maine

Routes recording Marsh Wren in Maine.
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 →
Warren219901986
Carrabassett120172017
Charleston120092006
Biddeford119811981
Hudson119971995
Bowdoin Ctr119941994
Washburn119941994
Harmony120072006
Jefferson120101991

Marsh Wren Population Trend in Other States

alabamaarizonacaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaslouisianamarylandmassachusettsmichiganminnesotamissourimontananebraskanevadanew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiooregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatexasutahvermontvirginiawashingtonwisconsinwyoming

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