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Species · Illinois · BBS 2025 Release · 1966–2024

Barn Swallow Population Trend in Illinois

All statesAerial insectivores

Barn Swallow in Illinois has edged up: up 10% on the route-weighted index since 1968.

+10%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 →
105Routes 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 Barn Swallow Trends in IllinoisNotable 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 Barn Swallow in Illinois. See the full index history below.

Barn Swallow Population Forecast in Illinois

If the recent trend holds, Barn Swallow in Illinois is projected to stay roughly flat through 2029, near 28 (95% range 21–36). A 5-year backtest shows a typical error of ±19.3%, with 100% of held-out values landing inside the 95% band.

+5%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 →
28Projected 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 →
21–3695% 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 →
±19.3%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, Barn Swallow in Illinois is projected to stay roughly flat through 2029, near 28 (95% range 21–36). A 5-year backtest shows a typical error of ±19.3%, 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 →
2025282036
2026282036
2027282036
2028282136
2029282136

Barn Swallow Survey Routes in Illinois

Routes recording Barn Swallow in Illinois.
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 →
Belleview9520241966
Sheffield7420241966
Atkinson7120241966
Melrose6819991973
Fairbury5420241976
Terre Haute5020241966
Eldred4820211993
Pontiac4520241978
Humboldt4120241970
Beaucoup4120241971
Shannon4020241993
Lake Galena4020212001
Keithsburg4020222001
Streator3920241972
Bremen3920241969
Belknap3920241970
Bluff Spgs3820241967
Columbia3820241966
Camp Point3820241993
Darmstadt3820241993
Royalton3720242001
Putnam3620241967
Buda3620231977
Chandlervill3620241971
Stillwell3520241971

Barn Swallow Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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