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

Bank Swallow Population Trend in California

All statesAerial insectivores

Bank Swallow in California has surged: up 505% on the route-weighted index since 1971.

+505%Since 1971TrendPercent 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 →
27Routes 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 →
54YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Bank 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 →

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 →

Bank Swallow has surged in California: up 505% on the route-weighted index since 1971.

Bank Swallow Population Forecast in California

If the recent trend holds, Bank Swallow in California is projected to rise about 15% by 2029 — from 0.20 in 2024 to a central estimate of 0.23 (95% range 0.00–1.2). A 5-year backtest shows a typical error of ±30.9%, with 100% of held-out values landing inside the 95% band.

+15%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 →
0.23Projected 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 →
0.00–1.295% 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 →
±30.9%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, Bank Swallow in California is projected to rise about 15% by 2029 — from 0.20 in 2024 to a central estimate of 0.23 (95% range 0.00–1.2). A 5-year backtest shows a typical error of ±30.9%, with 100% of held-out values landing inside the 95% band.19692029
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 →
20250.280.001.2
20260.270.001.2
20270.260.001.2
20280.240.001.2
20290.230.001.2

Bank Swallow Survey Routes in California

Routes recording Bank 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 →
Glenn11019971972
Jackson3119791979
Cedarville1320241977
Orland1019921992
Genesee620131995
Paxton520242000
Orleans520092009
Auburn419741974
Nubieber320071971
Hughson319841984
Elizabeth Lk219701970
Crowley Lake220212021
Parkfield219771971
Davis Creek219951995
Dorris220191972
Hay Fork220102010
Ingalls219921973
Adelaida219781972
Crescent Cty120242024
Red Bluff120212002
Pennington119911984
Fish Rock119691969
Likely119991972
Honey Lake120221972
Clear Lk Res119851985

Bank Swallow Population Trend in Other States

alabamaalaskaarkansascoloradoconnecticutdelawareidahoillinoisindianaiowakansaskentuckymainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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