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

Great Horned Owl Population Trend in Idaho

All statesBirds of prey

Great Horned Owl in Idaho has fallen sharply: down 55% on the route-weighted index since 1971.

-55%Since 1971TrendPercent 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 →
41Routes 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 →
52YearsYears 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 IdahoNotable 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 declinecomputed 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 →

Great Horned Owl has fallen sharply in Idaho: down 54% on the route-weighted index since 1971.

Great Horned Owl Population Forecast in Idaho

If the recent trend holds, Great Horned Owl in Idaho is projected to rise about 126% by 2030 — from 0.06 in 2025 to a central estimate of 0.13 (95% range 0.00–0.29). A 5-year backtest shows a typical error of ±78.9%, with 100% of held-out values landing inside the 95% band.

+126%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 →
0.13Projected 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 →
0.00–0.2995% 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 →
±78.9%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, Great Horned Owl in Idaho is projected to rise about 126% by 2030 — from 0.06 in 2025 to a central estimate of 0.13 (95% range 0.00–0.29). A 5-year backtest shows a typical error of ±78.9%, with 100% of held-out values landing inside the 95% band.19682030
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 →
20260.140.000.30
20270.130.000.30
20280.130.000.29
20290.130.000.29
20300.130.000.29

Great Horned Owl Survey Routes in Idaho

Routes recording Great Horned Owl in Idaho.
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 →
Bates520182014
Blackft Res319881987
Gifford319911971
Squirrel319941983
Almo320151994
Naples220241980
Baker220041984
Alturas219691968
Picabo220211990
Mora220222019
Mivoden120091999
Lolo Pass120101995
Grangeville120232008
Lost River120091991
Cascade119771973
Rochat Divde119961996
Challis119981998
Leadore120211981
Blacks Creek119821974
Centerville119901972
Craters120151984
Springfield120181977
Ririe120151971
Triangle120091989
Magic Mtn120161990

Great Horned Owl Population Trend in Other States

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

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