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

Great Horned Owl Population Trend in Pennsylvania

All statesGeneralists

Great Horned Owl in Pennsylvania has declined: down 36% on the route-weighted index since 1968.

-36%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 →
96Routes 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 →
57YearsYears 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 PennsylvaniaNotable 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 Pennsylvania. See the full index history below.

Great Horned Owl Population Forecast in Pennsylvania

If the recent trend holds, Great Horned Owl in Pennsylvania is projected to stay roughly flat through 2029, near 0.06 (95% range 0.00–0.16). A 5-year backtest shows a typical error of ±273.7%, with 100% of held-out values landing inside the 95% band.

n/aChange 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 →
0.06Projected 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 →
0.00–0.1695% 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 →
±273.7%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 Pennsylvania is projected to stay roughly flat through 2029, near 0.06 (95% range 0.00–0.16). A 5-year backtest shows a typical error of ±273.7%, with 100% 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 →
20250.060.000.16
20260.060.000.16
20270.060.000.16
20280.060.000.16
20290.060.000.16

Great Horned Owl Survey Routes in Pennsylvania

Routes recording Great Horned Owl in Pennsylvania.
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 →
Williamsburg320061988
Mifflintown320151996
Ferris Crnrs219981970
Odin219961996
Little Marsh220091967
Cherry Sprs219841976
Geeseytown220041997
Doubling Gap219661966
St College220191998
Pine Gr Mill220022002
Peters Mt219941994
Gatchelville219851984
Mt Gretna 2220182018
Stoneybreak220211996
Jacobus219921992
Broad Mtn.219971997
Espyville120221973
Clover119921981
Harmonsburg120162016
Whig Hill120031991
Teepleville119931973
Sigel120031996
Lynch119891989
N Washington119971976
N Pine Grove120032003

Great Horned Owl Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonrhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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