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

LeConte's Thrasher Population Trend in California

All statesGeneralists

LeConte's Thrasher in California has collapsed: down 97% on the route-weighted index since 1970.

-97%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 →
43Routes 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 →
56YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable LeConte'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 →

LeConte's Thrasher has collapsed in California: down 97% on the route-weighted index since 1970.

LeConte's Thrasher Population Forecast in California

If the recent trend holds, LeConte's Thrasher in California is projected to fall about 100% by 2029 — from 0.05 in 2024 to a central estimate of 0.00 (95% range 0.00–0.69). A 5-year backtest shows a typical error of ±478.3%, with 100% of held-out values landing inside the 95% band.

-100%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 →
0.00Projected 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 →
0.00–0.6995% 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 →
±478.3%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, LeConte's Thrasher in California is projected to fall about 100% by 2029 — from 0.05 in 2024 to a central estimate of 0.00 (95% range 0.00–0.69). A 5-year backtest shows a typical error of ±478.3%, 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 →
20250.000.000.69
20260.000.000.69
20270.000.000.69
20280.000.000.69
20290.000.000.69

LeConte's Thrasher Survey Routes in California

Routes recording LeConte'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 →
Willow Spgs1319811968
Goldstone920091968
Valley Wells520231969
Ivanpah520191989
Bakersfield419731968
Iron Mtns420172017
Death Valley419951975
Wildrose320221978
Barstow319961968
Havasu Lake319731973
Cottonwood320191973
Blythe319731973
Joshua Tree220001972
Carrizo Pln219721972
Cadiz219881988
Lenwood219931973
Joshua Tree 2220132013
Lone Pine220241970
Maricopa220241970
Kelso Valley119801975
Greenwater V120191972
Cholla Gard.120031995
Shafter119891971
Arvin119721971
Ubehebe119901990

LeConte's Thrasher Population Trend in Other States

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