BirdAnalyst
Species · BCR 32 · BBS 2025 Release · 1966–2024

California Gnatcatcher In Coastal California

All regionsCoastal CaliforniaForest birds

California Gnatcatcher in Coastal California has surged: up 88% on the route-weighted index since 1974.

+88%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 RegionSurvey 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 SignalsNotable 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 →

California Gnatcatcher has surged in Coastal California: up 88% on the route-weighted index since 1974.

Forecast

If the recent trend holds, California Gnatcatcher in Coastal California is projected to fall about 41% by 2029 — from 0.11 in 2024 to a central estimate of 0.06 (95% range 0.02–0.11). A 5-year backtest shows a typical error of ±57.2%, with 80% of held-out values landing inside the 95% band.

-41%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 →
0.06Projected 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 →
0.02–0.1195% 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 →
±57.2%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 Coastal California is projected to fall about 41% by 2029 — from 0.11 in 2024 to a central estimate of 0.06 (95% range 0.02–0.11). A 5-year backtest shows a typical error of ±57.2%, 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 →
20250.060.020.10
20260.060.020.11
20270.060.020.11
20280.060.020.11
20290.060.020.11

Routes In Coastal California

Routes recording California Gnatcatcher in Coastal 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 →
Oak GroveCALIFORNIA22017
Elsinore MtnCALIFORNIA21971
Harbor Lake 2CALIFORNIA22024
Jofegan 2CALIFORNIA22024
MorenoCALIFORNIA12024
San YsidroCALIFORNIA11988
Cp. PendletonCALIFORNIA12003
AnzaCALIFORNIA11976

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