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

Dickcissel Population Trend in Illinois

All statesGrassland birds

Dickcissel in Illinois has declined: down 39% on the route-weighted index since 1968.

-39%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 Dickcissel 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 Dickcissel in Illinois. See the full index history below.

Dickcissel Population Forecast in Illinois

If the recent trend holds, Dickcissel in Illinois is projected to fall about 29% by 2030 — from 32 in 2025 to a central estimate of 22 (95% range 2.2–43). A 5-year backtest shows a typical error of ±40.9%, with 100% of held-out values landing inside the 95% band.

-29%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 →
22Projected 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 →
2.2–4395% 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 →
±40.9%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, Dickcissel in Illinois is projected to fall about 29% by 2030 — from 32 in 2025 to a central estimate of 22 (95% range 2.2–43). A 5-year backtest shows a typical error of ±40.9%, 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 →
2026232.443
2027232.343
2028232.343
2029232.243
2030222.243

Dickcissel Survey Routes in Illinois

Routes recording Dickcissel 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 →
Harristown10320252006
Beaucoup9620251971
Humboldt9020251970
Stillwell7820251971
Buda6820231977
Gulfport6820251971
Greenview6720251993
Le Roy6620251993
Chandlervill6520251971
Brnt Prairie6320251976
Fairbury6220251976
Melrose6219991973
Concord West6220252001
Milford5720251966
Jamestown5620251966
Rosamond5520251972
Bluff Spgs5320251967
Duncan Mills5020251993
Guilford4820231967
Bradbury4620251970
Brownville4520251993
Payson4420252000
Lake Galena4220212001
Allerton Park4220252001
Camp Point4020251993

Dickcissel Population Trend in Other States

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