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

Barn Swallow Population Trend in Massachusetts

All statesAerial insectivores

Barn Swallow in Massachusetts has declined: down 36% on the route-weighted index since 1968.

-36%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 Barn Swallow 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 Barn Swallow in Massachusetts. See the full index history below.

Barn Swallow Population Forecast in Massachusetts

If the recent trend holds, Barn Swallow in Massachusetts is projected to fall about 30% by 2030 — from 6.6 in 2025 to a central estimate of 4.6 (95% range 1.4–7.8). A 5-year backtest shows a typical error of ±17.7%, with 100% of held-out values landing inside the 95% band.

-30%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 →
1.4–7.895% 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 →
±17.7%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, Barn Swallow in Massachusetts is projected to fall about 30% by 2030 — from 6.6 in 2025 to a central estimate of 4.6 (95% range 1.4–7.8). A 5-year backtest shows a typical error of ±17.7%, 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 →
20265.01.88.2
20274.91.78.1
20284.81.68.0
20294.71.57.9
20304.61.47.8

Barn Swallow Survey Routes in Massachusetts

Routes recording Barn Swallow 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 →
Pittsfield2320161967
Belchertown2120251967
Chilmark2019831969
Maynard1920251967
Cummington 21620252015
Gay Head1420241996
Cummington920141968
Hancock920151997
Princeton819761969
E Pepperell819941966
Chesterfield820251967
Marion720251966
Brockton720191967
Warren720091968
S Barre720251968
Littleton620251967
Mansfield620251968
Cheshire519941969
Monterey420252019
Ware River420221993
Holden420241977
Prattville320191966
Newburyport320211967
Sheffield320221969
Wellfleet 2320252016

Barn Swallow Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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