BirdAnalyst
Species · BCR 30 · BBS 2025 Release · 1966–2024

Chestnut-sided Warbler In New England / Mid-Atlantic Coast

All regionsNew England / Mid-Atlantic CoastForest birds

Chestnut-sided Warbler in New England / Mid-Atlantic Coast has declined: down 41% on the route-weighted index since 1968.

-41%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 →
62Routes 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 →
58YearsYears 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 Chestnut-sided Warbler in New England / Mid-Atlantic Coast. See the full index history below.

Forecast

If the recent trend holds, Chestnut-sided Warbler in New England / Mid-Atlantic Coast is projected to fall about 21% by 2029 — from 0.80 in 2024 to a central estimate of 0.64 (95% range 0.15–1.1). A 5-year backtest shows a typical error of ±26.2%, with 100% of held-out values landing inside the 95% band.

-21%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 →
0.64Projected 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 →
0.15–1.195% 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 →
±26.2%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, Chestnut-sided Warbler in New England / Mid-Atlantic Coast is projected to fall about 21% by 2029 — from 0.80 in 2024 to a central estimate of 0.64 (95% range 0.15–1.1). A 5-year backtest shows a typical error of ±26.2%, with 100% 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 →
20250.720.241.2
20260.700.221.2
20270.680.201.2
20280.660.181.1
20290.640.151.1

Routes In New England / Mid-Atlantic Coast

Routes recording Chestnut-sided Warbler 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 →
WarrenCONNECTICUT292011
S BarreMASSACHUSETTS152024
Ware RiverMASSACHUSETTS142022
Woodstock 2CONNECTICUT82024
GranbyCONNECTICUT72024
BelchertownMASSACHUSETTS72024
PrincetonMASSACHUSETTS51976
StraffordNEW-HAMPSHIRE52024
RooseveltNEW-JERSEY52007
E HartlandCONNECTICUT41992
WoodstockCONNECTICUT42007
Warren 2CONNECTICUT42024
East KingstonNEW-HAMPSHIRE42024
No WoodburyCONNECTICUT32024
HoldenMASSACHUSETTS32023
N. AndoverMASSACHUSETTS32004
Warren 2MASSACHUSETTS32024
ShermanCONNECTICUT22019
Long HillCONNECTICUT22017
MarionMASSACHUSETTS21977
WellfleetMASSACHUSETTS21987
MaynardMASSACHUSETTS22022
LittletonMASSACHUSETTS22024
E PepperellMASSACHUSETTS21993
WarrenMASSACHUSETTS22009

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