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

Bendire's Thrasher Population Trend in California

All statesGeneralists

Bendire's Thrasher in California has collapsed: down 88% on the route-weighted index since 1971.

-88%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 →
11Routes 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 →
42YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Bendire's Thrasher 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 declinecomputed 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 →

Bendire's Thrasher has collapsed in California: down 88% on the route-weighted index since 1971.

Bendire's Thrasher Population Forecast in California

If the recent trend holds, Bendire's Thrasher in California is projected to stay roughly flat through 2028, near 0.00 (95% range 0.00–0.04). A 5-year backtest shows a typical error of ±160.6%, with 100% of held-out values landing inside the 95% band.

n/aChange by 2028TrendPercent 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 →
0.00Projected 2028 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.0495% 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 →
±160.6%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, Bendire's Thrasher in California is projected to stay roughly flat through 2028, near 0.00 (95% range 0.00–0.04). A 5-year backtest shows a typical error of ±160.6%, with 100% of held-out values landing inside the 95% band.19692028
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 →
20240.000.000.04
20250.000.000.04
20260.000.000.04
20270.000.000.04
20280.000.000.04

Bendire's Thrasher Survey Routes in California

Routes recording Bendire's Thrasher 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 →
Joshua Tree519881975
Cholla Gard.319981995
Tecopa120151981
Kelso Valley120051997
Onyx119981998
Valley Wells120231996
Barstow119781969
Cima120211970
Cottonwood120161986
Ft Irwin119821982
Ivanpah120081996

Bendire's Thrasher Population Trend in Other States

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