BirdAnalyst
Species · BCR 33 · BBS 2025 Release · 1966–2024

California Thrasher In Sonoran and Mojave Deserts

All regionsSonoran and Mojave DesertsGeneralists

California Thrasher in Sonoran and Mojave Deserts has declined: down 29% on the route-weighted index since 1971.

-29%Since 1971TrendPercent 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 →
6Routes 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 →
45YearsYears 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 →

No notable trend signals for California Thrasher in Sonoran and Mojave Deserts. See the full index history below.

California Thrasher In Sonoran and Mojave Deserts Population Forecast

If the recent trend holds, California Thrasher in Sonoran and Mojave Deserts is projected to stay roughly flat through 2029, near 0.17 (95% range 0.00–0.34). A 5-year backtest shows a typical error of ±91.7%, with 100% of held-out values landing inside the 95% band.

n/aChange 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 →
0.17Projected 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 →
0.00–0.3495% 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 →
±91.7%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, California Thrasher in Sonoran and Mojave Deserts is projected to stay roughly flat through 2029, near 0.17 (95% range 0.00–0.34). A 5-year backtest shows a typical error of ±91.7%, with 100% of held-out values landing inside the 95% band.19692029
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 →
20250.160.000.34
20260.160.000.34
20270.170.000.34
20280.170.000.34
20290.170.000.34

Routes In Sonoran and Mojave Deserts

Routes recording California Thrasher in Sonoran and Mojave Deserts.
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 →
Anza BorregoCALIFORNIA22023
PearblossomCALIFORNIA22018
OnyxCALIFORNIA11998
Calif CityCALIFORNIA11979
Kelso ValleyCALIFORNIA12024
Joshua TreeCALIFORNIA11998

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