Species · BBS 2026 Release · 1966–2025

Marsh Wren Population Analysis

Troglodytidae Forest birdsCistothorus palustris

Marsh Wren has surged: up 150% on the route-weighted index since 1968.

+150%Since 1968

672Routes

59Years Surveyed

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 672 Breeding Bird Survey routes across 41 states, most concentrated in the Prairie Potholes.
Family: Troglodytidae · Forest birds

Notable Marsh Wren Trends

long arc increasecomputed index

Marsh Wren has surged in surveyed states: up 150% on the route-weighted index since 1968.

Marsh Wren Population Forecast

If the recent trend holds, Marsh Wren is projected to rise about 17% by 2030 — from 0.48 in 2025 to a central estimate of 0.56 (95% range 0.42–0.70). A 5-year backtest shows a typical error of ±21.5%, with 100% of held-out values landing inside the 95% band.

+17%Change by 2030

0.56Projected 2030 index

0.42–0.7095% range

±21.5%Backtest error

Projection of the recent trend (dashed) with 80/95% bands — a projection, not a prediction. Habitat, climate, and land use are not modeled.

Year	Projected index	95% low	95% high
2026	0.54	0.40	0.67
2027	0.54	0.41	0.68
2028	0.55	0.41	0.69
2029	0.56	0.42	0.69
2030	0.56	0.42	0.70

Where the Marsh Wren Is Detected

BBS routes recording Marsh Wren, sized by most recent count.

Marsh Wren Population Trend by State

Marsh Wren population trend by state.

Alabama	-79%	1968	3
Arizona	-10%	1994	4
California	+958%	1972	49
Colorado	-69%	1992	16
Connecticut	+442%	1977	7
Delaware	+233%	1968	9
Florida	insufficient data	n/a	5
Georgia	-89%	1970	4
Idaho	+10%	1980	17
Illinois	-34%	1979	13
Indiana	-81%	1981	7
Iowa	+193%	1978	11
Kansas	-21%	1981	4
Louisiana	-42%	1978	12
Maine	-8%	1987	9
Maryland	-82%	1968	10
Massachusetts	+209%	1970	6
Michigan	-51%	1971	25
Minnesota	+230%	1969	66
Missouri	insufficient data	n/a	1
Montana	+141%	1973	26
Nebraska	+121%	1969	18
Nevada	-21%	1995	12
New Hampshire	-22%	1970	6
New Jersey	-2%	1968	10
New York	-13%	1968	36
North Carolina	insufficient data	n/a	2
North Dakota	+977%	1969	47
Ohio	-28%	1974	10
Oregon	-27%	1973	34
Pennsylvania	-73%	1971	7
Rhode Island	insufficient data	n/a	1
South Carolina	-92%	1968	3
South Dakota	+295%	1969	23
Texas	-78%	1985	6
Utah	+14%	1993	14
Vermont	-42%	1970	8
Virginia	insufficient data	n/a	2
Washington	+171%	1970	50
Wisconsin	-40%	1968	54
Wyoming	-59%	1979	25

Marsh Wren Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

Marsh Wren population trend by Bird Conservation Region.

Northern Pacific Rainforest	+613%	1971	47
Great Basin	+584%	1971	76
Northern Rockies	+101%	1973	55
Prairie Potholes	+621%	1969	89
Boreal Hardwood Transition	+113%	1970	37
Lower Great Lakes / St. Lawrence Plain	+19%	1968	32
Atlantic Northern Forest	+92%	1973	24
Southern Rockies / Colorado Plateau	-77%	1992	16
Badlands and Prairies	-31%	1970	24
Shortgrass Prairie	-15%	1994	6
Central Mixed Grass Prairie	+143%	1970	15
Eastern Tallgrass Prairie	+350%	1971	32
Prairie Hardwood Transition	+19%	1968	85
Southeastern Coastal Plain	-92%	1968	15
Appalachian Mountains	-69%	1971	14
New England / Mid-Atlantic Coast	-28%	1968	45
Coastal California	11×	1973	26
Sonoran and Mojave Deserts	-39%	1975	11
Gulf Coastal Prairie	-53%	1980	16

Marsh Wren Conservation Status

Our route-weighted index shows it up about 150% since 1968.

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14. Trend is a route-weighted relative-abundance index, not an absolute population.