BirdAnalyst
Species · New Jersey · BBS 2025 Release · 1966–2024

Marsh Wren Population Trend in New Jersey

All statesForest birds

Marsh Wren in New Jersey has held roughly steady: down 5% on the route-weighted index since 1968.

-5%Since 1968TrendPercent 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 →
10Routes 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 →
47YearsYears 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 New JerseyNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

No notable trend signals for Marsh Wren in New Jersey. See the full index history below.

Marsh Wren Population Forecast in New Jersey

If the recent trend holds, Marsh Wren in New Jersey is projected to rise about 54% by 2029 — from 0.14 in 2024 to a central estimate of 0.22 (95% range 0.00–0.70). A 5-year backtest shows a typical error of ±70.1%, with 80% of held-out values landing inside the 95% band.

+54%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 →
0.22Projected 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 →
0.00–0.7095% 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 →
±70.1%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 New Jersey is projected to rise about 54% by 2029 — from 0.14 in 2024 to a central estimate of 0.22 (95% range 0.00–0.70). A 5-year backtest shows a typical error of ±70.1%, with 80% of held-out values landing inside the 95% band.19662029
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 →
20250.230.000.70
20260.220.000.70
20270.220.000.70
20280.220.000.70
20290.220.000.70

Marsh Wren Survey Routes in New Jersey

Routes recording Marsh Wren in New Jersey.
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 →
Pedricktown420121991
Pedricktown 2320242013
Del Haven219911991
Greenwich120011966
Six Points120101978
Hope119761976
Midvale119801975
Friendship119951995
Ocean City120001979
Villas119791979

Marsh Wren Population Trend in Other States

alabamaarizonacaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaslouisianamainemarylandmassachusettsmichiganminnesotamissourimontananebraskanevadanew-hampshirenew-yorknorth-carolinanorth-dakotaohiooregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatexasutahvermontvirginiawashingtonwisconsinwyoming

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