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Species · California · BBS 2025 Release · 1966–2024

Blue-gray Gnatcatcher Population Trend in California

All statesForest birds

Blue-gray Gnatcatcher in California has surged: up 532% on the route-weighted index since 1970.

+532%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 →
145Routes 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 Blue-gray 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 →

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 →

Blue-gray Gnatcatcher has surged in California: up 532% on the route-weighted index since 1970.

Blue-gray Gnatcatcher Population Forecast in California

If the recent trend holds, Blue-gray Gnatcatcher in California is projected to rise about 19% by 2029 — from 1.1 in 2024 to a central estimate of 1.3 (95% range 0.80–1.7). A 5-year backtest shows a typical error of ±50.9%, with 60% of held-out values landing inside the 95% band.

+19%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 →
1.3Projected 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 →
0.80–1.795% 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 →
±50.9%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, Blue-gray Gnatcatcher in California is projected to rise about 19% by 2029 — from 1.1 in 2024 to a central estimate of 1.3 (95% range 0.80–1.7). A 5-year backtest shows a typical error of ±50.9%, with 60% 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 →
20251.20.741.7
20261.20.751.7
20271.20.771.7
20281.30.791.7
20291.30.801.7

Blue-gray Gnatcatcher Survey Routes in California

Routes recording Blue-gray 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 →
Elsinore Mtn4120241987
Carmel Val1720241974
Bartlett Sps1320181973
Hullville1220191968
Santa Ynez1020191975
Lake Cachuma1020161972
Stonyford1020182015
Lake Hemet 2920231992
Hay Fork920172009
Rumsey820081980
Silver City720131994
Coulterville720191997
Yolla Bolly620231975
French Gulch620072002
Coalinga520051973
Mt Baldy520241978
Tehama520221973
Woodlands520242017
Hough Springs520071999
Friday Ridge520241995
Sawmill Mtn420221973
Fallsvale419751975
Longvale420231973
Clear Lk Res420141995
Iron Gate420191988

Blue-gray Gnatcatcher Population Trend in Other States

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