BirdAnalyst
Species · South Carolina · BBS 2025 Release · 1966–2024

Cliff Swallow Population Trend in South Carolina

All statesAerial insectivores

Cliff Swallow in South Carolina has surged: up 175% on the route-weighted index since 1990.

+175%Since 1990TrendPercent 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 →
9Routes 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 →
31YearsYears 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 South CarolinaNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

long arc increasecomputed indexTrend sourceWhether the figure is our own computed route-weighted index or an official USGS modeled estimate. The current build labels every trend as computed.Full methodology →

Cliff Swallow has surged in South Carolina: up 175% on the route-weighted index since 1990.

Cliff Swallow Population Forecast in South Carolina

If the recent trend holds, Cliff Swallow in South Carolina is projected to rise about 142% by 2029 — from 1.2 in 2024 to a central estimate of 3.0 (95% range 0.02–6.0). A 5-year backtest shows a typical error of ±343.9%, with 80% of held-out values landing inside the 95% band.

+142%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 →
3.0Projected 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 →
0.02–6.095% 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 →
±343.9%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 South Carolina is projected to rise about 142% by 2029 — from 1.2 in 2024 to a central estimate of 3.0 (95% range 0.02–6.0). A 5-year backtest shows a typical error of ±343.9%, with 80% of held-out values landing inside the 95% band.19872029
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 →
20252.70.005.7
20262.80.005.7
20272.80.005.8
20282.90.005.9
20293.00.026.0

Cliff Swallow Survey Routes in South Carolina

Routes recording Cliff Swallow in South Carolina.
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 →
Ridgeway5220212010
Blacksburg4520132006
Plum Branch1620241987
Owings 21020242006
Cauthens Xrd520081999
Prosperity519991999
Barton Creek220221989
Chesnee220022002
Owings119961996

Cliff Swallow Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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