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

Chimney Swift Population Trend in South Carolina

All statesAerial insectivores

Chimney Swift in South Carolina has collapsed: down 77% on the route-weighted index since 1968.

-77%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 →
51Routes 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 Chimney Swift 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 declinecomputed 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 →

Chimney Swift has collapsed in South Carolina: down 77% on the route-weighted index since 1968.

Chimney Swift Population Forecast in South Carolina

If the recent trend holds, Chimney Swift in South Carolina is projected to rise about 12% by 2029 — from 4.8 in 2024 to a central estimate of 5.4 (95% range 0.00–13). A 5-year backtest shows a typical error of ±63.8%, with 100% of held-out values landing inside the 95% band.

+12%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 →
5.4Projected 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 →
0.00–1395% 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 →
±63.8%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, Chimney Swift in South Carolina is projected to rise about 12% by 2029 — from 4.8 in 2024 to a central estimate of 5.4 (95% range 0.00–13). A 5-year backtest shows a typical error of ±63.8%, 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 →
20256.20.0014
20266.00.0013
20275.80.0013
20285.60.0013
20295.40.0013

Chimney Swift Survey Routes in South Carolina

Routes recording Chimney Swift 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 →
Owings3620041992
Joanna3320191999
Pendleton3119761966
Boykin Ml Pd3019681966
Little Mtn2719881966
Landrum2319921972
Salem Xrd2020191982
Wagener1820241966
Chesnee1720151992
Nixonville1419951987
New Holland1320241967
Dillon1320211970
Plum Branch1320241977
Blacksburg1120131998
Walterboro920171970
Barton Creek920221967
Boiling Spgs919791967
Carvers Bay920121998
Green Sea820242010
Holly Hill620241972
Foreston620191966
Campobello620242010
Sandhills620241994
Olar620191998
Bishopville520241970

Chimney Swift Population Trend in Other States

alabamaarkansascoloradoconnecticutdelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-dakotatennesseetexasvermontvirginiawest-virginiawisconsinwyoming

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