BirdAnalyst
Species · California · BBS 2026 Release · 1966–2025

Cliff Swallow Population Trend in California

All statesAerial insectivores

Cliff Swallow in California has held roughly steady: up 2% on the route-weighted index since 1970.

+2%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 →
217Routes 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 →
57YearsYears 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 rise about 12% by 2030 — from 50 in 2025 to a central estimate of 56 (95% range 26–87). A 5-year backtest shows a typical error of ±80.3%, with 60% of held-out values landing inside the 95% band.

+12%Change by 2030TrendPercent 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 →
56Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
26–8795% 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 →
±80.3%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 rise about 12% by 2030 — from 50 in 2025 to a central estimate of 56 (95% range 26–87). A 5-year backtest shows a typical error of ±80.3%, with 60% of held-out values landing inside the 95% band.19682030
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 →
2026582888
2027582788
2028572787
2029572687
2030562687

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
Ora Loma64720251972
Westley57920251972
Hughson44520251968
Shafter39019891971
Iron Gate38120191988
Pennington30920251971
Athlone29520071972
Imperial Dam26220101973
Zamora25020251972
Alamo River23320181973
Sanger22720242011
Staten Is.22720251994
Buena Vista22120191990
Orland19520171972
Paxton18420251998
Bridgeport16119771972
Nubieber16020181970
Auburn15919801969
Livermore13319911972
Rumsey12520081969
Cordova12319811971
Tracy12120091992
Fish Rock11920141968
Ravendale11920251985

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 2026-08-14.