BirdAnalyst
Species · BBS 2025 Release · 1966–2024

California Scrub-Jay

CorvidaeForest birdsAphelocoma californica

California Scrub-Jay has edged up: up 13% on the route-weighted index since 1970.

+13%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 →
259RoutesSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
56Years SurveyedYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

About the California Scrub-Jay

The California Scrub-Jay (Aphelocoma californica) is a North American member of the Crows, Jays & Magpies (Corvidae). In this analysis it is grouped with the forest birds.

Size
10–27.5 in long (25–70 cm) — a medium to large songbird (typical for the family)
Habitat
Woodlands and forest edges, including wooded suburbs and parks.
Diet
Insects and spiders gleaned from foliage and bark, with seeds and berries in season.
Range
Recorded on 259 Breeding Bird Survey routes across 4 states, most concentrated in the Coastal California.
Family
Corvidae · Forest birds

Notable California Scrub-Jay TrendsNotable 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 California Scrub-Jay. See the full index history below.

California Scrub-Jay Population Forecast

If the recent trend holds, California Scrub-Jay is projected to fall about 15% by 2029 — from 0.51 in 2024 to a central estimate of 0.44 (95% range 0.03–0.84). A 5-year backtest shows a typical error of ±4.4%, with 100% of held-out values landing inside the 95% band.

-15%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 →
0.44Projected 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 →
0.03–0.8495% 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 →
±4.4%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, California Scrub-Jay is projected to fall about 15% by 2029 — from 0.51 in 2024 to a central estimate of 0.44 (95% range 0.03–0.84). A 5-year backtest shows a typical error of ±4.4%, with 100% 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 →
20250.480.070.88
20260.470.060.87
20270.460.050.86
20280.450.040.85
20290.440.030.84

Where the California Scrub-Jay Is Detected

BBS routes recording California Scrub-Jay, sized by most recent count.

California Scrub-Jay Population Trend by State

California Scrub-Jay population trend by state.
TrendPercent 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 →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
California-17%1970200
Nevadainsufficient datan/a2
Oregon+51%197043
Washington+384%198214

California Scrub-Jay Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

California Scrub-Jay population trend by Bird Conservation Region.
TrendPercent 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 →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
Northern Pacific Rainforest-6%197077
Great Basin+38%197227
Sierra Nevada-80%197028
Coastal California-1%1970115
Sonoran and Mojave Deserts+66%19709

California Scrub-Jay Conservation Status

Our route-weighted index shows it up about 13% since 1970.

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22. Trend is a route-weighted relative-abundance index, not an absolute population.