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Species · California · BBS 2025 Release · 1966–2024

Cliff Swallow Population Trend in California

All statesAerial insectivores

Cliff Swallow in California has edged down: down 14% on the route-weighted index since 1970.

-14%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 →
215Routes 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 Cliff Swallow 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 Cliff Swallow in California. See the full index history below.

Cliff Swallow Population Forecast in California

If the recent trend holds, Cliff Swallow in California is projected to stay roughly flat through 2029, near 57 (95% range 27–88). A 5-year backtest shows a typical error of ±82.8%, with 60% of held-out values landing inside the 95% band.

+7%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 →
57Projected 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 →
27–8895% 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 →
±82.8%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, Cliff Swallow in California is projected to stay roughly flat through 2029, near 57 (95% range 27–88). A 5-year backtest shows a typical error of ±82.8%, 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 →
2025592889
2026592889
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2029572788

Cliff Swallow Survey Routes in California

Routes recording Cliff Swallow 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 →
Dorris191620191972
Hughson63120241968
Ora Loma60120241972
Pennington48420241971
Shafter39019891971
Iron Gate38120191988
Zamora30620241972
Athlone29520071972
Imperial Dam26220101973
Staten Is.24220241994
Alamo River23320181973
Sanger22720242011
Buena Vista22120191990
Paxton21520241998
Westley20720241972
Crowley Lake19620241972
Orland19520171972
Ravendale16620241985
Bridgeport16119771972
Nubieber16020181970
Auburn15919801969
Jofegan 213320242024
Livermore13319911972
Rumsey12520081969
Cordova12319811971

Cliff Swallow Population Trend in Other States

alabamaalaskaarizonaarkansascoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniasouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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