BirdAnalyst
Species · BCR 22 · BBS 2026 Release · 1966–2025

Chimney Swift In Eastern Tallgrass Prairie

All regionsEastern Tallgrass PrairieAerial insectivores

Chimney Swift in Eastern Tallgrass Prairie has collapsed: down 75% on the route-weighted index since 1968.

-75%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 →
274Routes 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 →
59YearsYears 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 collapsed in Eastern Tallgrass Prairie: down 75% on the route-weighted index since 1968.

Chimney Swift In Eastern Tallgrass Prairie Population Forecast

If the recent trend holds, Chimney Swift in Eastern Tallgrass Prairie is projected to fall about 31% by 2030 — from 3.7 in 2025 to a central estimate of 2.6 (95% range 0.00–5.7). A 5-year backtest shows a typical error of ±20.1%, with 100% of held-out values landing inside the 95% band.

-31%Change by 2030TrendPercent 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 →
2.6Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–5.795% 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 →
±20.1%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 Eastern Tallgrass Prairie is projected to fall about 31% by 2030 — from 3.7 in 2025 to a central estimate of 2.6 (95% range 0.00–5.7). A 5-year backtest shows a typical error of ±20.1%, with 100% of held-out values landing inside the 95% band.19662030
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 →
20263.30.156.5
20273.10.006.3
20282.90.006.1
20292.80.005.9
20302.60.005.7

Routes In Eastern Tallgrass Prairie

Routes recording Chimney Swift in Eastern Tallgrass Prairie.
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 →
ItascaILLINOIS792025
DunlapOHIO771988
TecumsehOHIO701982
GaryINDIANA601999
HarveysburgOHIO351996
WilmingtonOHIO351996
DesmoinesIOWA331979
Sni MillsMISSOURI331990
WestervilleOHIO301985
GildehouseMISSOURI291989
TroyOHIO281996
MiddletownINDIANA272025
St MorganILLINOIS232022
HamiltonMISSOURI221985
BotkinsOHIO202019
W CarrolltonOHIO202015
Sioux CityIOWA192025
West ElktonOHIO182012
ComptonILLINOIS172025
PlainfieldINDIANA171999
HolcombILLINOIS162025
MuncieINDIANA161997
Mascoutah LkILLINOIS152025
MaplewoodINDIANA152021
Cedar ValleyIOWA151997

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.