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

Cliff Swallow Population Trend in Connecticut

All statesAerial insectivores

Cliff Swallow in Connecticut has declined: down 42% on the route-weighted index since 1976.

-42%Since 1976TrendPercent 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 →
8Routes 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 →
24YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Cliff 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 Cliff Swallow in Connecticut. See the full index history below.

Cliff Swallow Population Forecast in Connecticut

If the recent trend holds, Cliff Swallow in Connecticut is projected to rise about 129% by 2026 — from 0.09 in 2021 to a central estimate of 0.21 (95% range 0.00–0.73). A 5-year backtest shows a typical error of ±100.9%, with 60% of held-out values landing inside the 95% band.

+129%Change by 2026TrendPercent 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 →
0.21Projected 2026 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.7395% 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 →
±100.9%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, Cliff Swallow in Connecticut is projected to rise about 129% by 2026 — from 0.09 in 2021 to a central estimate of 0.21 (95% range 0.00–0.73). A 5-year backtest shows a typical error of ±100.9%, with 60% of held-out values landing inside the 95% band.19732026
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 →
20220.220.000.74
20230.220.000.74
20240.210.000.74
20250.210.000.73
20260.210.000.73

Cliff Swallow Survey Routes in Connecticut

Routes recording Cliff 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 →
Warren720042004
New Hartford419871975
Danbury220082008
Sherman120051973
Long Hill120192005
Mid Haddam119861981
Warren 2120212021
Granby119911990

Cliff Swallow Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradodelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniasouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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