BirdAnalyst
Species · BCR 27 · BBS 2025 Release · 1966–2024

Chimney Swift In Southeastern Coastal Plain

All regionsSoutheastern Coastal PlainAerial insectivores

Chimney Swift in Southeastern Coastal Plain has fallen sharply: down 63% on the route-weighted index since 1968.

-63%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 →
342Routes In RegionSurvey 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 SignalsNotable 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 fallen sharply in Southeastern Coastal Plain: down 63% on the route-weighted index since 1968.

Forecast

If the recent trend holds, Chimney Swift in Southeastern Coastal Plain is projected to stay roughly flat through 2029, near 5.1 (95% range 1.5–8.7). A 5-year backtest shows a typical error of ±34.6%, with 100% of held-out values landing inside the 95% band.

+9%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 →
5.1Projected 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 →
1.5–8.795% 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 →
±34.6%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 Southeastern Coastal Plain is projected to stay roughly flat through 2029, near 5.1 (95% range 1.5–8.7). A 5-year backtest shows a typical error of ±34.6%, 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 →
20255.82.29.4
20265.62.09.2
20275.41.89.0
20285.31.78.9
20295.11.58.7

Routes In Southeastern Coastal Plain

Routes recording Chimney Swift in Southeastern Coastal Plain.
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 →
HowardALABAMA452024
GuytonGEORGIA441993
BeargrassNORTH-CAROLINA331981
ShallotteNORTH-CAROLINA311991
Boykin Ml PdSOUTH-CAROLINA301968
RiderwoodALABAMA262023
DarienGEORGIA242019
TazewellGEORGIA232024
Mt CarmelMISSISSIPPI222016
SpeedNORTH-CAROLINA212024
JamesvilleNORTH-CAROLINA212024
NewsomsVIRGINIA202024
St FlorianALABAMA192024
SlidellLOUISIANA191988
LacombeLOUISIANA181983
Trace LeeMISSISSIPPI182018
WagenerSOUTH-CAROLINA182024
Chowan RiverNORTH-CAROLINA172006
BaxleyGEORGIA152019
DortchesNORTH-CAROLINA152024
PinettaFLORIDA142024
DouglasGEORGIA141984
OwensboroGEORGIA142024
TupeloMISSISSIPPI142022
NixonvilleSOUTH-CAROLINA141995

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