BirdAnalyst
Species · Massachusetts · BBS 2025 Release · 1966–2024

Barn Swallow Population Trend in Massachusetts

All statesAerial insectivores

Barn Swallow in Massachusetts has declined: down 44% on the route-weighted index since 1968.

-44%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 →
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 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 37% by 2029 — from 7.3 in 2024 to a central estimate of 4.6 (95% range 1.3–7.8). A 5-year backtest shows a typical error of ±15%, with 100% of held-out values landing inside the 95% band.

-37%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 →
4.6Projected 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 →
1.3–7.895% 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 →
±15%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 37% by 2029 — from 7.3 in 2024 to a central estimate of 4.6 (95% range 1.3–7.8). A 5-year backtest shows a typical error of ±15%, 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 →
20255.01.78.2
20264.91.68.1
20274.81.58.0
20284.71.47.9
20294.61.37.8

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
Belchertown2120241967
Chilmark2019831969
Cummington 21620242015
Gay Head1420241996
Maynard1320221967
Chesterfield1320241967
Marion1120241966
Cummington920141968
Hancock920151997
Princeton819761969
E Pepperell819941966
Monterey820242019
Brockton720191967
Warren720091968
Littleton520231967
Mansfield520241968
S Barre520241968
Cheshire519941969
Ware River420221993
Wellfleet 2420242016
Holden420241977
Prattville320191966
Newburyport320211967
N Orange320241968

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 2026-05-22.