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Species · Massachusetts · BBS 2025 Release · 1966–2024

Nashville Warbler Population Trend in Massachusetts

All statesForest birds

Nashville Warbler in Massachusetts has fallen sharply: down 71% on the route-weighted index since 1968.

-71%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 →
22Routes 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 →
44YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Nashville 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 →

long arc declinecomputed 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 →

Nashville Warbler has fallen sharply in Massachusetts: down 71% on the route-weighted index since 1968.

Nashville Warbler Population Forecast in Massachusetts

If the recent trend holds, Nashville Warbler in Massachusetts is projected to fall about 100% by 2029 — from 0.07 in 2024 to a central estimate of 0.00 (95% range 0.00–0.69). A 5-year backtest shows a typical error of ±253.4%, with 100% of held-out values landing inside the 95% band.

-100%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 →
0.00Projected 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 →
0.00–0.6995% 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 →
±253.4%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, Nashville Warbler in Massachusetts is projected to fall about 100% by 2029 — from 0.07 in 2024 to a central estimate of 0.00 (95% range 0.00–0.69). A 5-year backtest shows a typical error of ±253.4%, 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 →
20250.000.000.69
20260.000.000.69
20270.000.000.69
20280.000.000.69
20290.000.000.69

Nashville Warbler Survey Routes in Massachusetts

Routes recording Nashville 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 →
Newburyport219671967
N Oxford219711971
E Pepperell219791966
Marion119711971
Wellfleet119861970
Prattville120072004
Ware River119931993
Maynard119721967
Princeton119741972
Belchertown120191972
Warren119901969
S Barre119811971
N Orange120071968
Cummington120131971
Chesterfield120041968
Cheshire119811974
Pittsfield120051990
Sheffield119981996
Monterey120242023
Holden119921979
Cummington 2120192019
Hancock119971997

Nashville Warbler Population Trend in Other States

californiaconnecticutidahomainemarylandmichiganminnesotamontananew-hampshirenew-jerseynew-yorknorth-dakotaoregonpennsylvaniarhode-islandvermontvirginiawashingtonwest-virginiawisconsin

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