BirdAnalyst
Species · BCR 32 · BBS 2026 Release · 1966–2025

Great Horned Owl In Coastal California

All regionsCoastal CaliforniaBirds of prey

Great Horned Owl in Coastal California has surged: up 184% on the route-weighted index since 1972.

+184%Since 1972TrendPercent 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 RegionSurvey 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 SignalsNotable 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 increasecomputed 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 surged in Coastal California: up 184% on the route-weighted index since 1972.

Great Horned Owl In Coastal California Population Forecast

If the recent trend holds, Great Horned Owl in Coastal California is projected to fall about 38% by 2030 — from 1.3 in 2025 to a central estimate of 0.78 (95% range 0.40–1.2). A 5-year backtest shows a typical error of ±42.6%, with 20% of held-out values landing inside the 95% band.

-38%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 →
0.78Projected 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 →
0.40–1.295% 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 →
±42.6%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 Coastal California is projected to fall about 38% by 2030 — from 1.3 in 2025 to a central estimate of 0.78 (95% range 0.40–1.2). A 5-year backtest shows a typical error of ±42.6%, with 20% of held-out values landing inside the 95% band.19702030
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 →
20260.760.381.1
20270.770.391.1
20280.770.391.1
20290.770.401.1
20300.780.401.2

Routes In Coastal California

Routes recording Great Horned Owl in Coastal California.
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 →
PolomaCALIFORNIA122023
PenningtonCALIFORNIA82014
TujungaCALIFORNIA81977
AdelaidaCALIFORNIA62025
OnoCALIFORNIA52009
Point ReyesCALIFORNIA42022
Mesa GrandeCALIFORNIA42025
Carmel ValCALIFORNIA42025
AnzaCALIFORNIA41974
JacumbaCALIFORNIA42025
CoyoteCALIFORNIA42025
Foster ParkCALIFORNIA31994
HollisterCALIFORNIA31997
Lake HemetCALIFORNIA31973
Cuyamaca PkCALIFORNIA32025
SangerCALIFORNIA32024
AtwaterCALIFORNIA32012
WestleyCALIFORNIA32025
ReddingCALIFORNIA31979
Mark WestCALIFORNIA32022
Ora LomaCALIFORNIA32025
Lake Hemet 2CALIFORNIA32016
Cleveland NfCALIFORNIA32016
Tres Pinos 2CALIFORNIA32009
RiovistaCALIFORNIA22025

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