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

Song Sparrow Population Trend in Illinois

All statesGeneralists

Song Sparrow in Illinois has edged down: down 17% on the route-weighted index since 1968.

-17%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 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 rise about 17% by 2029 — from 14 in 2024 to a central estimate of 17 (95% range 9.1–25). A 5-year backtest shows a typical error of ±20.7%, with 100% of held-out values landing inside the 95% band.

+17%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 →
17Projected 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 →
9.1–2595% 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 →
±20.7%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 rise about 17% by 2029 — from 14 in 2024 to a central estimate of 17 (95% range 9.1–25). A 5-year backtest shows a typical error of ±20.7%, 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 →
2025179.325
2026179.325
2027179.225
2028179.225
2029179.125

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 →
Janesville4720241972
Robinson4220231970
Bradbury4120241970
Brnt Prairie4020241976
Fairdale3420242019
St Morgan3320221967
Alden3220232019
Kell3220242001
Jamestown3120241966
York3120241993
Union3120172001
Marshall3020242002
Wayne2820241966
Yale2820241993
Humboldt2720241970
Sheffield2520241966
Beaucoup2520241971
Atkinson2420241966
Lake Summerset2420222001
Sterling2420232001
Grape Creek2420242001
Milford2320231966
Athensville2320241971
Darmstadt2320241993
Lake Galena2320212001

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 2026-05-22.