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Species · Massachusetts · BBS 2025 Release · 1966–2024

Chestnut-sided Warbler Population Trend in Massachusetts

All statesForest birds

Chestnut-sided Warbler in Massachusetts has increased: up 50% on the route-weighted index since 1968.

+50%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 →
28Routes 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 →
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 Chestnut-sided Warbler Trends in MassachusettsNotable 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 Massachusetts. See the full index history below.

Chestnut-sided Warbler Population Forecast in Massachusetts

If the recent trend holds, Chestnut-sided Warbler in Massachusetts is projected to fall about 38% by 2029 — from 6.3 in 2024 to a central estimate of 3.9 (95% range 1.2–6.6). A 5-year backtest shows a typical error of ±30.7%, with 80% of held-out values landing inside the 95% band.

-38%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 →
3.9Projected 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 →
1.2–6.695% 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 →
±30.7%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, Chestnut-sided Warbler in Massachusetts is projected to fall about 38% by 2029 — from 6.3 in 2024 to a central estimate of 3.9 (95% range 1.2–6.6). A 5-year backtest shows a typical error of ±30.7%, 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 →
20254.11.46.7
20264.01.36.7
20274.01.36.6
20283.91.36.6
20293.91.26.6

Chestnut-sided Warbler Survey Routes in Massachusetts

Routes recording Chestnut-sided Warbler in Massachusetts.
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 →
Chesterfield1920241967
Pittsfield1920161967
Cummington 21920242015
N Orange1720241968
S Barre1520241968
Cummington1520141968
Ware River1420221993
Monterey1220242019
Sheffield1020221969
Hancock820151997
Belchertown720241967
Princeton519761969
Cheshire519941969
Holden320231977
N. Andover320041995
Warren 2320242010
Marion219771969
Wellfleet219871971
Maynard220221967
Littleton220241967
E Pepperell219931966
Warren220091968
E Dennis119871970
Chilmark119711969
Prattville120041966

Chestnut-sided Warbler Population Trend in Other States

alabamaarkansascoloradoconnecticutgeorgiaillinoisindianaiowakansaskentuckymainemarylandmichiganminnesotanevadanew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiopennsylvaniarhode-islandtennesseevermontvirginiawest-virginiawisconsinwyoming

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