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

Marsh Wren Population Trend in Wisconsin

All statesForest birds

Marsh Wren in Wisconsin has declined: down 31% on the route-weighted index since 1968.

-31%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 →
54Routes 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 Marsh Wren Trends in WisconsinNotable 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 Wisconsin. See the full index history below.

Marsh Wren Population Forecast in Wisconsin

If the recent trend holds, Marsh Wren in Wisconsin is projected to fall about 20% by 2029 — from 0.21 in 2024 to a central estimate of 0.17 (95% range 0.00–0.46). A 5-year backtest shows a typical error of ±56.1%, with 100% of held-out values landing inside the 95% band.

-20%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 →
0.17Projected 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 →
0.00–0.4695% 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 →
±56.1%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, Marsh Wren in Wisconsin is projected to fall about 20% by 2029 — from 0.21 in 2024 to a central estimate of 0.17 (95% range 0.00–0.46). A 5-year backtest shows a typical error of ±56.1%, 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 →
20250.180.000.48
20260.180.000.47
20270.170.000.47
20280.170.000.47
20290.170.000.46

Marsh Wren Survey Routes in Wisconsin

Routes recording Marsh Wren in Wisconsin.
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 →
Wis Rapids820231966
Iron River520241967
Bayfield519821982
Manitowoc420051975
Hatfield319951971
Hudson220151984
Cumberland219741974
Princeton219761970
Beaver Dam220231966
Buena Vista220232023
Briggsville220231999
Paris220241966
Chaffey119901990
Minong119941980
Shanagolden119861986
Montreal119851983
Dresser120231967
Loraine120051974
Weyerhauser119941994
Exeland120052004
Gilman120211981
Holway119701970
Omro 2120242004
Mcnaughton120182018
Esdaile119931969

Marsh Wren Population Trend in Other States

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

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