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

Black Swift Population Trend in California

All statesAerial insectivores

Black Swift in California has declined: down 30% on the route-weighted index since 1973.

-30%Since 1973TrendPercent 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 →
30Routes 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 →
39YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Black Swift 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 Black Swift in California. See the full index history below.

Black Swift Population Forecast in California

If the recent trend holds, Black Swift in California is projected to stay roughly flat through 2029, near 0.02 (95% range 0.00–0.18). A 5-year backtest shows a typical error of ±74.7%, with 100% 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 →
0.02Projected 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 →
0.00–0.1895% 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 →
±74.7%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, Black Swift in California is projected to stay roughly flat through 2029, near 0.02 (95% range 0.00–0.18). A 5-year backtest shows a typical error of ±74.7%, with 100% 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 →
20250.020.000.19
20260.020.000.19
20270.020.000.18
20280.020.000.18
20290.020.000.18

Black Swift Survey Routes in California

Routes recording Black Swift 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 →
Yolla Bolly4819801980
Holmes2519991999
Sanger1020182018
Lake Hemet819861972
White River719921973
Cal Hot Spgs720162007
Angelus Oaks520171989
Fallsvale419751975
Rumsey319941994
Jackson319921992
Orange Cove320041977
Waterman Gap320242016
Cohasset319801980
Carmel Val319831983
Lockwood219861973
Lake Success219961972
Coyote219841984
Mt Baldy120151971
Kings Canyon120041974
Fish Rock119781978
Bass Lake120081975
Coulterville119981998
Foster Park119711971
Kernville120082008
Cedarville119941994

Black Swift Population Trend in Other States

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