BirdAnalyst
Species · BBS 2025 Release · 1966–2024

California Gnatcatcher

PolioptilidaeForest birdsPolioptila californica

California Gnatcatcher has edged down: down 15% on the route-weighted index since 1974.

-15%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 →
8RoutesSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
20Years SurveyedYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

About the California Gnatcatcher

The California Gnatcatcher (Polioptila californica) is a North American member of the Gnatcatchers (Polioptilidae). In this analysis it is grouped with the forest birds.

Size
4–5 in long (10–13 cm) — a tiny, long-tailed songbird (typical for the family)
Habitat
Woodlands and forest edges, including wooded suburbs and parks.
Diet
Insects and spiders gleaned from foliage and bark, with seeds and berries in season.
Range
Recorded on 8 Breeding Bird Survey routes across 1 state, most concentrated in the Coastal California.
Family
Polioptilidae · Forest birds

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

California Gnatcatcher Population Forecast

If the recent trend holds, California Gnatcatcher is projected to stay roughly flat through 2029, near 0.00 (95% range 0.00–0.00). A 5-year backtest shows a typical error of ±56.9%, with 80% of held-out values landing inside the 95% band.

n/aChange 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 →
0.00–0.0095% 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 is projected to stay roughly flat through 2029, near 0.00 (95% range 0.00–0.00). 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 →
20250.000.000.00
20260.000.000.00
20270.000.000.00
20280.000.000.00
20290.000.000.00

Where the California Gnatcatcher Is Detected

BBS routes recording California Gnatcatcher, sized by most recent count.

California Gnatcatcher Population Trend by State

California Gnatcatcher population trend by state.
TrendPercent 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 →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
California+58%19748

California Gnatcatcher Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

California Gnatcatcher population trend by Bird Conservation Region.
TrendPercent 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 →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
Coastal California+88%19748

California Gnatcatcher Conservation Status

Our route-weighted index shows it down about 15% since 1974.

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22. Trend is a route-weighted relative-abundance index, not an absolute population.