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

Red-shouldered Hawk Population Trend in California

All statesGeneralists

Red-shouldered Hawk in California has surged: up 521% on the route-weighted index since 1970.

+521%Since 1970TrendPercent 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 →
129Routes 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 →
56YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Red-shouldered Hawk Trends in CaliforniaNotable 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 →

Red-shouldered Hawk has surged in California: up 521% on the route-weighted index since 1970.

Red-shouldered Hawk Population Forecast in California

If the recent trend holds, Red-shouldered Hawk in California is projected to stay roughly flat through 2029, near 0.86 (95% range 0.62–1.1). A 5-year backtest shows a typical error of ±23.7%, with 80% of held-out values landing inside the 95% band.

+5%Change 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 →
0.86Projected 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 →
0.62–1.195% 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 →
±23.7%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, Red-shouldered Hawk in California is projected to stay roughly flat through 2029, near 0.86 (95% range 0.62–1.1). A 5-year backtest shows a typical error of ±23.7%, with 80% of held-out values landing inside the 95% band.19682029
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 →
20250.810.571.0
20260.820.591.1
20270.830.601.1
20280.850.611.1
20290.860.621.1

Red-shouldered Hawk Survey Routes in California

Routes recording Red-shouldered Hawk in 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 →
Fairfax1520241978
Coyote1220241995
Bass Lake520192007
San Ysidro520191977
Silver City520131978
Gold Hill520231995
Alderpoint520121975
Harbor Lake 2520242014
Pennington420221984
Lake Success419961980
Navarro420111972
Moraga420241974
Tres Pinos 2420112005
Collegeville 2420142009
Jofegan 2320242024
Calpella319861973
Orange Cove320161976
Morro Bay320191974
Sawmill Mtn320131973
El Toro319991973
Elsinore Mtn320241971
Elizabeth Lk320161976
Laytonville320241973
Mark West320241973
Zamora320241974

Red-shouldered Hawk Population Trend in Other States

alabamaarkansasconnecticutdelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourinebraskanew-hampshirenew-jerseynew-yorknorth-carolinaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinatennesseetexasvermontvirginiawashingtonwest-virginiawisconsin

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