Marsh Wren
Marsh Wren has surged: up 136% on the route-weighted index since 1968.
About the Marsh Wren
The Marsh Wren (Cistothorus palustris) is a North American member of the Wrens (Troglodytidae). In this analysis it is grouped with the forest birds.
- Size
- 4–8.5 in long (10–22 cm) — a small, energetic songbird (typical for the family)
- Habitat
- Woodlands and forest edges, including wooded suburbs and parks.
- Diet
- Insects and spiders gleaned from foliage and bark, with seeds and berries in season.
- Range
- Recorded on 657 Breeding Bird Survey routes across 41 states, most concentrated in the Prairie Potholes.
- Family
- Troglodytidae · Forest birds
Notable Marsh Wren Trends
Marsh Wren has surged in surveyed states: up 136% on the route-weighted index since 1968.
Marsh Wren Population Forecast
If the recent trend holds, Marsh Wren is projected to rise about 25% by 2029 — from 0.44 in 2024 to a central estimate of 0.56 (95% range 0.42–0.69). A 5-year backtest shows a typical error of ±27.4%, with 100% of held-out values landing inside the 95% band.
| Year | Projected index | 95% low | 95% high |
|---|---|---|---|
| 2025 | 0.53 | 0.39 | 0.67 |
| 2026 | 0.54 | 0.40 | 0.68 |
| 2027 | 0.54 | 0.41 | 0.68 |
| 2028 | 0.55 | 0.41 | 0.69 |
| 2029 | 0.56 | 0.42 | 0.69 |
Where the Marsh Wren Is Detected
BBS routes recording Marsh Wren, sized by most recent count.
Marsh Wren Population Trend by State
| Alabama | -79% | 1968 | 3 |
| Arizona | -10% | 1994 | 4 |
| California | +811% | 1972 | 48 |
| Colorado | -66% | 1992 | 16 |
| Connecticut | +445% | 1977 | 7 |
| Delaware | +248% | 1968 | 9 |
| Florida | insufficient data | n/a | 5 |
| Georgia | -89% | 1970 | 4 |
| Idaho | -53% | 1980 | 15 |
| Illinois | -76% | 1979 | 10 |
| Indiana | -82% | 1981 | 6 |
| Iowa | +97% | 1978 | 9 |
| Kansas | -21% | 1981 | 4 |
| Louisiana | -15% | 1978 | 12 |
| Maine | -8% | 1987 | 9 |
| Maryland | -82% | 1968 | 10 |
| Massachusetts | +350% | 1970 | 6 |
| Michigan | -51% | 1971 | 25 |
| Minnesota | +204% | 1969 | 66 |
| Missouri | insufficient data | n/a | 1 |
| Montana | +181% | 1973 | 26 |
| Nebraska | +14% | 1969 | 17 |
| Nevada | -13% | 1995 | 11 |
| New Hampshire | -21% | 1970 | 6 |
| New Jersey | -5% | 1968 | 10 |
| New York | +13% | 1968 | 36 |
| North Carolina | insufficient data | n/a | 2 |
| North Dakota | +924% | 1969 | 47 |
| Ohio | -19% | 1974 | 9 |
| Oregon | -1% | 1973 | 33 |
| Pennsylvania | -73% | 1971 | 7 |
| Rhode Island | insufficient data | n/a | 1 |
| South Carolina | -95% | 1968 | 3 |
| South Dakota | +282% | 1969 | 23 |
| Texas | -55% | 1985 | 5 |
| Utah | +24% | 1993 | 14 |
| Vermont | -43% | 1970 | 8 |
| Virginia | insufficient data | n/a | 2 |
| Washington | +150% | 1970 | 49 |
| Wisconsin | -31% | 1968 | 54 |
| Wyoming | -57% | 1979 | 25 |
Marsh Wren Population Trend by Region
Bird Conservation Regions are the ecological unit for trends.
| Northern Pacific Rainforest | +582% | 1971 | 46 |
| Great Basin | +646% | 1971 | 72 |
| Northern Rockies | +145% | 1973 | 55 |
| Prairie Potholes | +584% | 1969 | 89 |
| Boreal Hardwood Transition | +206% | 1970 | 37 |
| Lower Great Lakes / St. Lawrence Plain | +41% | 1968 | 31 |
| Atlantic Northern Forest | +92% | 1973 | 24 |
| Southern Rockies / Colorado Plateau | -70% | 1992 | 16 |
| Badlands and Prairies | +59% | 1970 | 24 |
| Shortgrass Prairie | -15% | 1994 | 6 |
| Central Mixed Grass Prairie | +13% | 1970 | 15 |
| Eastern Tallgrass Prairie | +93% | 1971 | 25 |
| Prairie Hardwood Transition | +18% | 1968 | 85 |
| Southeastern Coastal Plain | -96% | 1968 | 15 |
| Appalachian Mountains | -69% | 1971 | 14 |
| New England / Mid-Atlantic Coast | -24% | 1968 | 45 |
| Coastal California | +864% | 1973 | 25 |
| Sonoran and Mojave Deserts | -22% | 1975 | 11 |
| Gulf Coastal Prairie | -54% | 1980 | 15 |
Marsh Wren Conservation Status
Our route-weighted index shows it up about 136% since 1968.
Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22. Trend is a route-weighted relative-abundance index, not an absolute population.