BirdAnalyst
Species · BCR 30 · BBS 2026 Release · 1966–2025

Marsh Wren In New England / Mid-Atlantic Coast

All regionsNew England / Mid-Atlantic CoastForest birds

Marsh Wren in New England / Mid-Atlantic Coast has declined: down 28% on the route-weighted index since 1968.

-28%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 →
45Routes In RegionSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
59YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable SignalsNotable 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 England / Mid-Atlantic Coast. See the full index history below.

Marsh Wren In New England / Mid-Atlantic Coast Population Forecast

If the recent trend holds, Marsh Wren in New England / Mid-Atlantic Coast is projected to fall about 26% by 2030 — from 0.57 in 2025 to a central estimate of 0.42 (95% range 0.15–0.69). A 5-year backtest shows a typical error of ±41.7%, with 60% of held-out values landing inside the 95% band.

-26%Change by 2030TrendPercent 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 →
0.42Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.15–0.6995% 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 →
±41.7%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 England / Mid-Atlantic Coast is projected to fall about 26% by 2030 — from 0.57 in 2025 to a central estimate of 0.42 (95% range 0.15–0.69). A 5-year backtest shows a typical error of ±41.7%, with 60% of held-out values landing inside the 95% band.19662030
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 →
20260.430.160.69
20270.420.160.69
20280.420.150.69
20290.420.150.69
20300.420.150.69

Routes In New England / Mid-Atlantic Coast

Routes recording Marsh Wren in New England / Mid-Atlantic Coast.
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 →
BlackbirdDELAWARE142025
NewburyportMASSACHUSETTS122022
Pedricktown 2NEW-JERSEY82025
Milton 2DELAWARE72025
PedricktownNEW-JERSEY42012
Chincoteag WVIRGINIA42024
WestbrookCONNECTICUT32025
Bethany BchDELAWARE31990
Piney NeckMARYLAND31980
HarmonyMARYLAND31968
BerlinMARYLAND32005
Jones BeachNEW-YORK32006
Warren 2CONNECTICUT22024
Lowes XrdsDELAWARE21991
Broomes IslMARYLAND21966
ElktonMARYLAND21988
HongaMARYLAND22025
MadisonMARYLAND22025
CokesburyMARYLAND22025
BrocktonMASSACHUSETTS21987
DoverNEW-HAMPSHIRE22025
Del HavenNEW-JERSEY21991
WesthamptonNEW-YORK22006
MysticCONNECTICUT12017
BuckinghamCONNECTICUT12014

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.