BirdAnalyst
Species · Massachusetts · BBS 2026 Release · 1966–2025

Chimney Swift Population Trend in Massachusetts

All statesAerial insectivores

Chimney Swift in Massachusetts has declined: down 48% on the route-weighted index since 1968.

-48%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 →
32Routes 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 →
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 Chimney Swift 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 Chimney Swift in Massachusetts. See the full index history below.

Chimney Swift Population Forecast in Massachusetts

If the recent trend holds, Chimney Swift in Massachusetts is projected to fall about 41% by 2030 — from 7.8 in 2025 to a central estimate of 4.6 (95% range 1.2–8.0). A 5-year backtest shows a typical error of ±20.5%, with 100% of held-out values landing inside the 95% band.

-41%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 →
4.6Projected 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 →
1.2–8.095% 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 →
±20.5%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, Chimney Swift in Massachusetts is projected to fall about 41% by 2030 — from 7.8 in 2025 to a central estimate of 4.6 (95% range 1.2–8.0). A 5-year backtest shows a typical error of ±20.5%, with 100% 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 →
20265.01.58.4
20274.91.48.3
20284.81.48.2
20294.71.38.1
20304.61.28.0

Chimney Swift Survey Routes in Massachusetts

Routes recording Chimney Swift 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 →
Maynard2820251967
E Pepperell2719941966
Prattville1820191966
Warren1820091968
N Orange1720251968
Mansfield1520251968
Marion1420251966
N Oxford1020251968
Hancock820141997
Wellfleet719971966
S Barre720251968
Newburyport620221967
Belchertown620251967
Chesterfield620251967
Holden620251977
Warren 2620252010
E Dennis520211967
Brockton520191967
Cheshire519931969
Pittsfield520161967
Gay Head320252017
N. Andover320251995
Monterey220252019
Ware River220191994
Cummington 2220252016

Chimney Swift Population Trend in Other States

alabamaarkansascoloradoconnecticutdelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemarylandmichiganminnesotamississippimissourimontananebraskanew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasvermontvirginiawest-virginiawisconsinwyoming

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