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

Lucy's Warbler Population Trend in California

All statesArid-land birds

Lucy's Warbler in California has surged: up 101% on the route-weighted index since 1980.

+101%Since 1980TrendPercent 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 →
3Routes 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 →
24YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Lucy's Warbler 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 →

No notable trend signals for Lucy's Warbler in California. See the full index history below.

Lucy's Warbler Population Forecast in California

If the recent trend holds, Lucy's Warbler in California is projected to stay roughly flat through 2028, near 0.03 (95% range 0.01–0.04). A 5-year backtest shows a typical error of ±45.9%, with 80% 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 →
0.03Projected 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 →
0.01–0.0495% 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 →
±45.9%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, Lucy's Warbler in California is projected to stay roughly flat through 2028, near 0.03 (95% range 0.01–0.04). A 5-year backtest shows a typical error of ±45.9%, with 80% of held-out values landing inside the 95% band.19752028
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 →
20240.020.010.04
20250.020.010.04
20260.020.010.04
20270.030.010.04
20280.030.010.04

Lucy's Warbler Survey Routes in California

Routes recording Lucy's Warbler 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 →
Tecopa220231979
Alamo River219751975
Death Valley119851985

Lucy's Warbler Population Trend in Other States

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