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

Tree Swallow Population Trend in Connecticut

All statesAerial insectivores

Tree Swallow in Connecticut has edged up: up 13% on the route-weighted index since 1968.

+13%Since 1968
20Routes In State
58Years

Notable Tree Swallow Trends in Connecticut

No notable trend signals for Tree Swallow in Connecticut. See the full index history below.

Tree Swallow Population Forecast in Connecticut

If the recent trend holds, Tree Swallow in Connecticut is projected to rise about 33% by 2029 — from 4.9 in 2024 to a central estimate of 6.5 (95% range 0.55–12). A 5-year backtest shows a typical error of ±109.7%, with 100% of held-out values landing inside the 95% band.

+33%Change by 2029
6.5Projected 2029 index
0.55–1295% range
±109.7%Backtest error
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 index95% low95% high
20256.30.3712
20266.40.4112
20276.40.4612
20286.50.5012
20296.50.5512

Tree Swallow Survey Routes in Connecticut

Routes recording Tree Swallow in Connecticut.
Warren1320111972
Sherman920191972
Mid Haddam820241973
Woodstock720071968
Westbrook720241972
Willimantic620181967
No Woodbury620241967
Long Hill620181972
Southington620241973
New Hartford620241994
Buckingham420221966
Uncasville420241979
Warren 2420242012
New Hartford319871972
Mystic220221973
E Hartland219921966
Greenwich220171968
Woodstock 2220242016
Danbury120221968
Granby120241988

Tree 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.