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

Barred Owl Population Trend in Illinois

All statesGeneralists

Barred Owl in Illinois has surged: up 379% on the route-weighted index since 1968.

+379%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 →
76Routes 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 Barred Owl 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 →

long arc increasecomputed indexTrend sourceWhether the figure is our own computed route-weighted index or an official USGS modeled estimate. The current build labels every trend as computed.Full methodology →

Barred Owl has surged in Illinois: up 379% on the route-weighted index since 1968.

Barred Owl Population Forecast in Illinois

If the recent trend holds, Barred Owl in Illinois is projected to fall about 37% by 2029 — from 0.44 in 2024 to a central estimate of 0.28 (95% range 0.11–0.44). A 5-year backtest shows a typical error of ±38.2%, with 40% of held-out values landing inside the 95% band.

-37%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 →
0.28Projected 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 →
0.11–0.4495% 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 →
±38.2%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, Barred Owl in Illinois is projected to fall about 37% by 2029 — from 0.44 in 2024 to a central estimate of 0.28 (95% range 0.11–0.44). A 5-year backtest shows a typical error of ±38.2%, with 40% 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 →
20250.260.100.43
20260.270.100.43
20270.270.100.44
20280.270.100.44
20290.280.110.44

Barred Owl Survey Routes in Illinois

Routes recording Barred Owl 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 →
Bremen820241973
Mascoutah Lk520241972
Humboldt420192019
Camp Point420161995
Cameron320241980
Belknap320241970
Sheffield220241990
Payson220042004
Grape Creek220232022
Monticello220001993
Athensville220231979
Belleview220241966
Kell220242003
Pulaski220241970
Robinson220232023
Seneca220191999
Karnak220232003
Cave In Rock220221994
Guilford120231977
Mill Creek120122012
Cherry Val120021995
Athens120242001
Atkinson120032003
Geneseo120091990
Putnam120011992

Barred Owl Population Trend in Other States

alabamaalaskaarkansascaliforniaconnecticutdelawarefloridageorgiaidahoindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanew-hampshirenew-jerseynew-yorknorth-carolinaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinatennesseetexasvermontvirginiawashingtonwest-virginiawisconsin

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