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

Great Horned Owl Population Trend in Maine

All statesGeneralists

Great Horned Owl in Maine has declined: down 32% on the route-weighted index since 1980.

-32%Since 1980TrendPercent 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 →
18Routes 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 →
18YearsYears 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 MaineNotable 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 Maine. See the full index history below.

Great Horned Owl Population Forecast in Maine

If the recent trend holds, Great Horned Owl in Maine is projected to stay roughly flat through 2024, near 0.03 (95% range 0.00–0.07). A 5-year backtest shows a typical error of ±60.5%, with 80% of held-out values landing inside the 95% band.

n/aChange by 2024TrendPercent 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 →
0.03Projected 2024 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.0795% 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 →
±60.5%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 Maine is projected to stay roughly flat through 2024, near 0.03 (95% range 0.00–0.07). A 5-year backtest shows a typical error of ±60.5%, with 80% of held-out values landing inside the 95% band.19752024
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 →
20200.030.000.08
20210.030.000.08
20220.030.000.08
20230.030.000.07
20240.030.000.07

Great Horned Owl Survey Routes in Maine

Routes recording Great Horned Owl in Maine.
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 →
South Arm219921992
Bowdoin Ctr219801980
Brooks219951995
Westbrook119941992
Biddeford119991975
Kittery Pt120022002
Priestly Br.120002000
Bethel120102010
Benedicta119931993
Greenwood120171981
Reeds119831983
Hudson119831983
Warren119821982
Rome120192019
Hancock119761976
Weeks Brook119971997
Cooper120172017
Deblois119801980

Great Horned Owl Population Trend in Other States

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

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