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Species · Illinois · BBS 2026 Release · 1966–2025

Barn Swallow Population Trend in Illinois

All statesAerial insectivores

Barn Swallow in Illinois has edged up: up 13% on the route-weighted index since 1968.

+13%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 →
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 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 2030, near 28 (95% range 20–36). A 5-year backtest shows a typical error of ±13.6%, with 100% of held-out values landing inside the 95% band.

+7%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 →
28Projected 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 →
20–3695% 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 →
±13.6%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, Barn Swallow in Illinois is projected to stay roughly flat through 2030, near 28 (95% range 20–36). A 5-year backtest shows a typical error of ±13.6%, 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 →
2026282035
2027282036
2028282036
2029282036
2030282036

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 →
Belleview7520251966
Sheffield7420241966
Atkinson7120241966
Chandlervill6820251971
Melrose6819991973
Marshall6520252001
Greenview6120251993
Pontiac5320251978
Gulfport4920251971
Terre Haute4820251966
Humphrey4820251972
Geneseo4720251967
Belknap4720251970
Athensville4420251971
Monticello4320251976
Mascoutah Lk4120251967
Lake Summerset4120252001
Janesville4020251972
Lake Galena4020212001
Darmstadt3920251993
Gridley3920252001
Bremen3820251969
Putnam3620241967
Buda3620231977
Robinson3520231970

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 2026-08-14.