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

Marsh Wren Population Trend in Washington

All statesForest birds

Marsh Wren in Washington has surged: up 150% on the route-weighted index since 1970.

+150%Since 1970TrendPercent 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 →
49Routes 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 WashingtonNotable 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 Washington: up 150% on the route-weighted index since 1970.

Marsh Wren Population Forecast in Washington

If the recent trend holds, Marsh Wren in Washington is projected to rise about 86% by 2029 — from 0.53 in 2024 to a central estimate of 0.98 (95% range 0.58–1.4). A 5-year backtest shows a typical error of ±90.3%, with 20% of held-out values landing inside the 95% band.

+86%Change by 2029TrendPercent 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 →
0.98Projected 2029 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.58–1.495% 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 →
±90.3%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 Washington is projected to rise about 86% by 2029 — from 0.53 in 2024 to a central estimate of 0.98 (95% range 0.58–1.4). A 5-year backtest shows a typical error of ±90.3%, with 20% of held-out values landing inside the 95% band.19682029
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 →
20250.920.531.3
20260.940.541.3
20270.950.561.3
20280.960.571.4
20290.980.581.4

Marsh Wren Survey Routes in Washington

Routes recording Marsh Wren in Washington.
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 →
Reardan1920142000
Mendota 31020242005
Mendota 2920001989
Raymond 2520242023
Raymond520211994
Brewster420152000
Issaquah419861980
Ardenvoir419681968
Mcchord420151996
Tonasket420102007
South Elma420241991
Taholah320181975
Ewan320191985
Potholes320231996
Mukilteo320191994
Warm Beach 2320222018
Ewan 2220242024
Moses Lake220221975
Bunker Hill220241969
Kendall220181984
Cusick220182002
Mendota219861981
Scootney Reservoir220242009
Malden220242003
Ozette120031985

Marsh Wren Population Trend in Other States

alabamaarizonacaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaslouisianamainemarylandmassachusettsmichiganminnesotamissourimontananebraskanevadanew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiooregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatexasutahvermontvirginiawisconsinwyoming

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