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

Marsh Wren Population Trend in Iowa

All statesForest birds

Marsh Wren in Iowa has surged: up 97% on the route-weighted index since 1978.

+97%Since 1978
9Routes In State
26Years

Notable Marsh Wren Trends in Iowa

long arc increasecomputed index

Marsh Wren has surged in Iowa: up 97% on the route-weighted index since 1978.

Marsh Wren Population Forecast in Iowa

If the recent trend holds, Marsh Wren in Iowa is projected to fall about 15% by 2029 — from 0.14 in 2024 to a central estimate of 0.12 (95% range 0.00–0.29). A 5-year backtest shows a typical error of ±63.7%, with 100% of held-out values landing inside the 95% band.

-15%Change by 2029
0.12Projected 2029 index
0.00–0.2995% range
±63.7%Backtest error
19732029
Projection of the recent trend (dashed) with 80/95% bands — a projection, not a prediction. Habitat, climate, and land use are not modeled.
YearProjected index95% low95% high
20250.110.000.29
20260.120.000.29
20270.120.000.29
20280.120.000.29
20290.120.000.29

Marsh Wren Survey Routes in Iowa

Routes recording Marsh Wren in Iowa.
Kanawha320242021
Burchinal120122012
Williamsburg119961996
Tipton120212021
Panther120082008
Alice119881978
Scranton120171975
Sioux City120221973
Garner119751975

Marsh Wren Population Trend in Other States

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

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