BirdAnalyst
Species · BBS 2025 Release · 1966–2024

California Thrasher

MimidaeArid-land birdsToxostoma redivivum

California Thrasher has held roughly steady: down 8% on the route-weighted index since 1970.

-8%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 →
115RoutesSurvey 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 Thrasher

The California Thrasher (Toxostoma redivivum) is a North American member of the Mockingbirds & Thrashers (Mimidae). In this analysis it is grouped with the arid-land birds.

Size
8–12 in long (20–30 cm) — a slender, long-tailed songbird (typical for the family)
Habitat
Deserts, dry scrub and brushland of the Southwest.
Diet
Seeds, insects and cactus fruit of arid-land plants.
Range
Recorded on 115 Breeding Bird Survey routes across 1 state, most concentrated in the Coastal California.
Family
Mimidae · Arid-land birds

Notable California Thrasher 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 Thrasher. See the full index history below.

California Thrasher Population Forecast

If the recent trend holds, California Thrasher is projected to fall about 76% by 2029 — from 0.07 in 2024 to a central estimate of 0.02 (95% range 0.00–0.09). A 5-year backtest shows a typical error of ±75.2%, with 100% of held-out values landing inside the 95% band.

-76%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 →
0.02Projected 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 →
0.00–0.0995% 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 →
±75.2%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 Thrasher is projected to fall about 76% by 2029 — from 0.07 in 2024 to a central estimate of 0.02 (95% range 0.00–0.09). A 5-year backtest shows a typical error of ±75.2%, 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 →
20250.020.000.10
20260.020.000.10
20270.020.000.10
20280.020.000.09
20290.020.000.09

Where the California Thrasher Is Detected

BBS routes recording California Thrasher, sized by most recent count.

California Thrasher Population Trend by State

California Thrasher 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-4%1970115

California Thrasher Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

California Thrasher 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-90%19719
Great Basin-4%19953
Sierra Nevada-88%197313
Coastal California+15%197084
Sonoran and Mojave Deserts-29%19716

California Thrasher Conservation Status

Our route-weighted index shows it down about 8% 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.