Species · Delaware · BBS 2025 Release · 1966–2024
Marsh Wren Population Trend in Delaware
Marsh Wren in Delaware has surged: up 248% on the route-weighted index since 1968.
+248%Since 1968
9Routes In State
54Years
Notable Marsh Wren Trends in Delaware
long arc increasecomputed index
Marsh Wren has surged in Delaware: up 248% on the route-weighted index since 1968.
Marsh Wren Population Forecast in Delaware
If the recent trend holds, Marsh Wren in Delaware is projected to stay roughly flat through 2029, near 3.3 (95% range 1.7–4.9). A 5-year backtest shows a typical error of ±28.4%, with 80% of held-out values landing inside the 95% band.
-3%Change by 2029
3.3Projected 2029 index
1.7–4.995% range
±28.4%Backtest error
| Year | Projected index | 95% low | 95% high |
|---|---|---|---|
| 2025 | 3.1 | 1.5 | 4.8 |
| 2026 | 3.2 | 1.5 | 4.8 |
| 2027 | 3.2 | 1.6 | 4.9 |
| 2028 | 3.3 | 1.6 | 4.9 |
| 2029 | 3.3 | 1.7 | 4.9 |
Marsh Wren Survey Routes in Delaware
| Blackbird | 15 | 2024 | 1994 |
| Bethany Bch | 3 | 1990 | 1967 |
| Harrington | 2 | 2024 | 1967 |
| Lowes Xrds | 2 | 1991 | 1991 |
| Milton 2 | 2 | 2017 | 2017 |
| Wilmington | 1 | 2014 | 1966 |
| Dover | 1 | 1986 | 1966 |
| Milton | 1 | 2011 | 1966 |
| Georgetown | 1 | 2022 | 1995 |
Marsh Wren Population Trend in Other States
alabamaarizonacaliforniacoloradoconnecticutfloridageorgiaidahoillinoisindianaiowakansaslouisianamainemarylandmassachusettsmichiganminnesotamissourimontananebraskanevadanew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiooregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatexasutahvermontvirginiawashingtonwisconsinwyoming
Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22.