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Species · Connecticut · BBS 2025 Release · 1966–2024

Barn Swallow Population Trend in Connecticut

All statesAerial insectivores

Barn Swallow in Connecticut has edged up: up 18% on the route-weighted index since 1968.

+18%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 →
20Routes 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 ConnecticutNotable 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 Connecticut. See the full index history below.

Barn Swallow Population Forecast in Connecticut

If the recent trend holds, Barn Swallow in Connecticut is projected to fall about 23% by 2029 — from 12 in 2024 to a central estimate of 8.9 (95% range 4.4–13). A 5-year backtest shows a typical error of ±22.1%, with 80% of held-out values landing inside the 95% band.

-23%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 →
8.9Projected 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 →
4.4–1395% 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 →
±22.1%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 Connecticut is projected to fall about 23% by 2029 — from 12 in 2024 to a central estimate of 8.9 (95% range 4.4–13). A 5-year backtest shows a typical error of ±22.1%, 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 →
20259.04.514
20269.04.513
20279.04.513
20289.04.413
20298.94.413

Barn Swallow Survey Routes in Connecticut

Routes recording Barn Swallow in Connecticut.
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 →
Mystic4520231973
Westbrook3120241969
Uncasville3020241977
Willimantic1520181968
New Hartford1519871972
Woodstock 21220242016
Woodstock1120071968
Buckingham920221966
Granby820241988
Mid Haddam720241973
Southington620241973
Warren 2620242013
E Hartland419921966
No Woodbury420241967
Sherman320191972
Danbury320231968
Warren320111972
Greenwich220181967
Long Hill120191972
New Hartford120241994

Barn Swallow Population Trend in Other States

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

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