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Species · Montana · BBS 2026 Release · 1966–2025

Marsh Wren Population Trend in Montana

All statesForest birds

Marsh Wren in Montana has surged: up 141% on the route-weighted index since 1973.

+141%Since 1973TrendPercent 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 →
53YearsYears 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 MontanaNotable 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 →

Marsh Wren has surged in Montana: up 141% on the route-weighted index since 1973.

Marsh Wren Population Forecast in Montana

If the recent trend holds, Marsh Wren in Montana is projected to rise about 23% by 2030 — from 0.27 in 2025 to a central estimate of 0.33 (95% range 0.14–0.51). A 5-year backtest shows a typical error of ±11.9%, with 100% of held-out values landing inside the 95% band.

+23%Change by 2030TrendPercent 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 →
0.33Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.14–0.5195% 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 →
±11.9%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 Montana is projected to rise about 23% by 2030 — from 0.27 in 2025 to a central estimate of 0.33 (95% range 0.14–0.51). A 5-year backtest shows a typical error of ±11.9%, with 100% of held-out values landing inside the 95% band.19682030
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 →
20260.310.120.50
20270.310.130.50
20280.320.130.50
20290.320.140.51
20300.330.140.51

Marsh Wren Survey Routes in Montana

Routes recording Marsh Wren in Montana.
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 →
Westby1220252015
Willow Creek 2720251985
Kalispell220241979
Redstone220171978
Polson219991997
Elliston219911991
Two Dot220182018
Beaverhead220241994
Ester Lake220172017
Libby Dam119881988
Cleveland120232023
Glen120251978
Oswego120191996
Arlee120061991
Augusta120251993
Highwood120081993
Brusett120171985
Twin Bridges119761968
Laurel120192019
Brandenberg119741974
Red Rock119891989
Wolf Point120152015
Wolf Creek120152015
Pablo Res.120251998
Miles City120192019

Marsh Wren Population Trend in Other States

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

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.