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

Great Horned Owl Population Trend in Illinois

All statesGeneralists

Great Horned Owl in Illinois has declined: down 27% on the route-weighted index since 1970.

-27%Since 1970
89Routes In State
56Years

Notable Great Horned Owl Trends in Illinois

No notable trend signals for Great Horned Owl in Illinois. See the full index history below.

Great Horned Owl Population Forecast in Illinois

If the recent trend holds, Great Horned Owl in Illinois is projected to stay roughly flat through 2029, near 0.11 (95% range 0.00–0.30). A 5-year backtest shows a typical error of ±357.3%, with 100% of held-out values landing inside the 95% band.

n/aChange by 2029
0.11Projected 2029 index
0.00–0.3095% range
±357.3%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
20250.120.000.31
20260.110.000.31
20270.110.000.30
20280.110.000.30
20290.110.000.30

Great Horned Owl Survey Routes in Illinois

Routes recording Great Horned Owl in Illinois.
Humboldt520191977
Mill Creek320231971
Cherry Val219951977
Compton220061984
Streator219851981
Newark220211995
Williamsfld219921979
Milford220011992
Clarksdale220141988
Janesville219811981
Jamestown219961996
Mt Vernon219981992
Bremen220121970
Beaverdam Lk219941985
Lake Summerset220112002
Waynesville220122002
Royalton220232023
Guilford119881984
Holcomb119851985
Barrington120051995
Geneseo120151973
Putnam119991974
Sheffield120141966
Buda120231985
Wayne120031988

Great Horned Owl Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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