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

Great Horned Owl Population Trend in Iowa

All statesGeneralists

Great Horned Owl in Iowa has declined: down 41% on the route-weighted index since 1969.

-41%Since 1969TrendPercent 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 →
36Routes 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 →
55YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Great Horned Owl Trends in IowaNotable 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 Great Horned Owl in Iowa. See the full index history below.

Great Horned Owl Population Forecast in Iowa

If the recent trend holds, Great Horned Owl in Iowa is projected to fall about 26% by 2028 — from 0.14 in 2023 to a central estimate of 0.10 (95% range 0.00–0.32). A 5-year backtest shows a typical error of ±47.7%, with 100% of held-out values landing inside the 95% band.

-26%Change by 2028TrendPercent 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 →
0.10Projected 2028 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.3295% 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 →
±47.7%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, Great Horned Owl in Iowa is projected to fall about 26% by 2028 — from 0.14 in 2023 to a central estimate of 0.10 (95% range 0.00–0.32). A 5-year backtest shows a typical error of ±47.7%, with 100% of held-out values landing inside the 95% band.19672028
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 →
20240.110.000.33
20250.110.000.33
20260.110.000.33
20270.100.000.32
20280.100.000.32

Great Horned Owl Survey Routes in Iowa

Routes recording Great Horned Owl in Iowa.
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 →
Melrose320091975
Neola220061969
Prairieburg219921971
Kanawha220221985
Titonka220081977
College Spgs 2220232007
Mt Hamill120191978
Exline120211980
Bedford120161970
College Spgs119921972
Bryant120021977
West Liberty120001972
Cedar Valley119961967
Brooklyn120161968
Williamsburg119971974
Red Rock119891972
Panther120231977
Washington120141967
Wales120171967
Maquoketa120171985
Hudson120211982
Dinsdale119961984
Zearing119941981
Scranton120181973
Clare120101979

Great Horned Owl Population Trend in Other States

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

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