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

Sage Thrasher Population Trend in California

All statesGeneralists

Sage Thrasher in California has surged: up 286% on the route-weighted index since 1973.

+286%Since 1973TrendPercent 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 →
31Routes 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 →
53YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Sage 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 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 →

Sage Thrasher has surged in California: up 286% on the route-weighted index since 1973.

Sage Thrasher Population Forecast in California

If the recent trend holds, Sage Thrasher in California is projected to fall about 39% by 2029 — from 2.5 in 2024 to a central estimate of 1.5 (95% range 0.62–2.4). A 5-year backtest shows a typical error of ±15.7%, with 80% of held-out values landing inside the 95% band.

-39%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 →
1.5Projected 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 →
0.62–2.495% 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 →
±15.7%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, Sage Thrasher in California is projected to fall about 39% by 2029 — from 2.5 in 2024 to a central estimate of 1.5 (95% range 0.62–2.4). A 5-year backtest shows a typical error of ±15.7%, with 80% of held-out values landing inside the 95% band.19712029
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 →
20251.50.582.4
20261.50.592.4
20271.50.602.4
20281.50.612.4
20291.50.622.4

Sage Thrasher Survey Routes in California

Routes recording Sage 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 →
Crowley Lake7620241972
Benton6220241973
Bodie3220241982
Ravendale2920241973
Honey Lake1420241972
Wildrose1119931992
Sattley720241974
Dorris720191973
Big Pine620241971
Haiwee Res419981976
Macdoel420191972
Bridgeport419771972
Clear Lk Res420181977
Chilcoot420241998
Darwin420011992
Likely320181974
Crowder Flat220182006
Onyx219921980
Last Chance220142009
Gazelle120012001
Dardanelle119961974
Tionesta120191997
Madeline120242010
Davis Creek119931993
Crestview120181997

Sage Thrasher Population Trend in Other States

arizonacoloradoidahomontananebraskanevadanew-mexiconorth-dakotaoregonsouth-dakotautahwashingtonwyoming

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