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Species · California · BBS 2025 Release · 1966–2024

California Gnatcatcher Population Trend in California

All statesForest birds

California Gnatcatcher in California has risen sharply: up 58% on the route-weighted index since 1974.

+58%Since 1974TrendPercent 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 →
8Routes 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 →
20YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable California Gnatcatcher 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 California Gnatcatcher in California. See the full index history below.

California Gnatcatcher Population Forecast in California

If the recent trend holds, California Gnatcatcher in California is projected to fall about 48% by 2029 — from 0.05 in 2024 to a central estimate of 0.03 (95% range 0.01–0.05). A 5-year backtest shows a typical error of ±56.9%, with 80% of held-out values landing inside the 95% band.

-48%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 →
0.03Projected 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 →
0.01–0.0595% 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 →
±56.9%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, California Gnatcatcher in California is projected to fall about 48% by 2029 — from 0.05 in 2024 to a central estimate of 0.03 (95% range 0.01–0.05). A 5-year backtest shows a typical error of ±56.9%, 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 →
20250.030.000.05
20260.030.010.05
20270.030.010.05
20280.030.010.05
20290.030.010.05

California Gnatcatcher Survey Routes in California

Routes recording California Gnatcatcher 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 →
Jofegan 2220242024
Oak Grove220171973
Elsinore Mtn219711971
Harbor Lake 2220242016
Moreno120242017
San Ysidro119881987
Cp. Pendleton120031987
Anza119761976

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