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

Chimney Swift Population Trend in Delaware

All statesAerial insectivores

Chimney Swift in Delaware has declined: down 41% on the route-weighted index since 1968.

-41%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 →
17Routes 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 DelawareNotable 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 Chimney Swift in Delaware. See the full index history below.

Chimney Swift Population Forecast in Delaware

If the recent trend holds, Chimney Swift in Delaware is projected to rise about 35% by 2029 — from 4.8 in 2024 to a central estimate of 6.5 (95% range 1.1–12). A 5-year backtest shows a typical error of ±67.3%, with 100% of held-out values landing inside the 95% band.

+35%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 →
6.5Projected 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 →
1.1–1295% 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 →
±67.3%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 Delaware is projected to rise about 35% by 2029 — from 4.8 in 2024 to a central estimate of 6.5 (95% range 1.1–12). A 5-year backtest shows a typical error of ±67.3%, 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 →
20256.71.412
20266.61.312
20276.61.212
20286.51.212
20296.51.112

Chimney Swift Survey Routes in Delaware

Routes recording Chimney Swift in Delaware.
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 →
Dover2319871966
Lowes Xrds2019911966
Harrington1620241966
Milton1220161966
Milton 2820172017
Wilmington720141966
Bethany Bch719901966
Holleyville620041966
Frederica520141966
Mt Pleasant420191966
Holleyville 2420242006
Georgetown420181992
Frankford320121966
Pepperbox320161998
Pepperbox 2320242017
Blackbird120241994
Millsboro120192017

Chimney Swift Population Trend in Other States

alabamaarkansascoloradoconnecticutfloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasvermontvirginiawest-virginiawisconsinwyoming

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