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

Blue Grosbeak Population Trend in Illinois

All statesGeneralists

Blue Grosbeak in Illinois has surged: up 46× on the route-weighted index since 1968.

46×Since 1968
77Routes In State
58Years

Notable Blue Grosbeak Trends in Illinois

long arc increasecomputed index

Blue Grosbeak has surged in Illinois: up 46× on the route-weighted index since 1968.

Blue Grosbeak Population Forecast in Illinois

If the recent trend holds, Blue Grosbeak in Illinois is projected to fall about 43% by 2029 — from 4.8 in 2024 to a central estimate of 2.8 (95% range 1.6–3.9). A 5-year backtest shows a typical error of ±43.6%, with 20% of held-out values landing inside the 95% band.

-43%Change by 2029
2.8Projected 2029 index
1.6–3.995% range
±43.6%Backtest error
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 index95% low95% high
20252.61.43.7
20262.61.43.8
20272.71.53.8
20282.71.53.9
20292.81.63.9

Blue Grosbeak Survey Routes in Illinois

Routes recording Blue Grosbeak in Illinois.
Karnak1920242001
Bremen1620241970
Beaverdam Lk1520231970
Mt Vernon1420241973
Brownville1420241993
Kell1420242001
Royalton1420242001
Delwood1320241970
Belleview1220241968
Janesville1220242001
Flora1220241981
Belknap1120241970
Sandusky1120231993
Marshall1120242016
Brnt Prairie1020241980
York1020242017
Cave In Rock1020241993
Payson1020242004
Bradbury920241997
Olney920241983
Dudleyville920242001
Mascoutah Lk820242005
Jamestown820241988
Robinson820232021
Monticello720241999

Blue Grosbeak Population Trend in Other States

alabamaarizonaarkansascaliforniacoloradodelawarefloridageorgiaidahoindianaiowakansaskentuckylouisianamarylandminnesotamississippimissourimontananebraskanevadanew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniasouth-carolinasouth-dakotatennesseetexasutahvirginiawest-virginiawyoming

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