BirdAnalyst
Species · Illinois · BBS 2026 Release · 1966–2025

Song Sparrow Population Trend in Illinois

All statesForest birds

Song Sparrow in Illinois has edged down: down 11% on the route-weighted index since 1968.

-11%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 Song Sparrow 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 Song Sparrow in Illinois. See the full index history below.

Song Sparrow Population Forecast in Illinois

If the recent trend holds, Song Sparrow in Illinois is projected to stay roughly flat through 2030, near 17 (95% range 9.0–25). A 5-year backtest shows a typical error of ±21.6%, with 100% of held-out values landing inside the 95% band.

+3%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 →
17Projected 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 →
9.0–2595% 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 →
±21.6%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, Song Sparrow in Illinois is projected to stay roughly flat through 2030, near 17 (95% range 9.0–25). A 5-year backtest shows a typical error of ±21.6%, 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 →
2026179.325
2027179.225
2028179.225
2029179.125
2030179.025

Song Sparrow Survey Routes in Illinois

Routes recording Song Sparrow 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 →
Janesville4820251972
Robinson4220231970
Bradbury4020251970
Brnt Prairie3920251976
Fairdale3520252019
Marshall3420252002
St Morgan3320221967
Wayne3220251966
Humboldt3220251970
Kell3220252001
Union3120172001
Alden3020252019
Holcomb2920251971
Geneseo2920251967
Jamestown2720251966
York2720251993
Sheffield2520241966
Milford2520251966
Darmstadt2520251993
Atkinson2420241966
Compton2420251968
Beaucoup2420251971
Caledonia2420251993
Sterling2420232001
Concord2320251967

Song Sparrow Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawaregeorgiaidahoindianaiowakansaskentuckymainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseeutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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