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

Great Horned Owl Population Trend in Maryland

All statesGeneralists

Great Horned Owl in Maryland has declined: down 46% on the route-weighted index since 1968.

-46%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 →
55Routes 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 MarylandNotable 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 Maryland. See the full index history below.

Great Horned Owl Population Forecast in Maryland

If the recent trend holds, Great Horned Owl in Maryland is projected to stay roughly flat through 2029, near 0.14 (95% range 0.00–0.39). A 5-year backtest shows a typical error of ±289.4%, 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 →
0.14Projected 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 →
0.00–0.3995% 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 →
±289.4%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 Maryland is projected to stay roughly flat through 2029, near 0.14 (95% range 0.00–0.39). A 5-year backtest shows a typical error of ±289.4%, 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 →
20250.150.000.39
20260.150.000.39
20270.140.000.39
20280.140.000.39
20290.140.000.39

Great Horned Owl Survey Routes in Maryland

Routes recording Great Horned Owl in Maryland.
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 →
Upper Xrds719941983
Matthews520111980
Honga420211966
Piney Neck320181969
Smithsburg220042004
Warfieldsbrg220061967
La Plata219971997
Pomfret220141983
Northeast220121970
Melitota220241977
Harmony220051969
Vienna220221971
Fruitland219941983
Furnace Town220162016
Vindex119771977
Oldtown119851985
Potomac Park119951979
Williamsport120032003
Grove Neck119951992
Emmitsburg119921992
Bald Friar119941993
Olney119931992
Bachman Mill119831983
Fowblesburg120081984
Eklo119851968

Great Horned Owl Population Trend in Other States

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

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