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

Bank Swallow Population Trend in Iowa

All statesAerial insectivores

Bank Swallow in Iowa has collapsed: down 92% on the route-weighted index since 1969.

-92%Since 1969TrendPercent 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 →
34Routes 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 →
55YearsYears 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 IowaNotable 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 declinecomputed 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 collapsed in Iowa: down 92% on the route-weighted index since 1969.

Bank Swallow Population Forecast in Iowa

If the recent trend holds, Bank Swallow in Iowa is projected to rise about 285% by 2029 — from 0.27 in 2024 to a central estimate of 1.1 (95% range 0.00–3.5). A 5-year backtest shows a typical error of ±817.5%, with 100% of held-out values landing inside the 95% band.

+285%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 →
1.1Projected 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 →
0.00–3.595% 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 →
±817.5%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 Iowa is projected to rise about 285% by 2029 — from 0.27 in 2024 to a central estimate of 1.1 (95% range 0.00–3.5). A 5-year backtest shows a typical error of ±817.5%, with 100% of held-out values landing inside the 95% band.19672029
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 →
20251.10.003.5
20261.10.003.5
20271.10.003.5
20281.10.003.5
20291.10.003.5

Bank Swallow Survey Routes in Iowa

Routes recording Bank Swallow in Iowa.
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 →
Dinsdale1520151969
Cedar Valley1019971968
Prairieburg820131968
Desmoines719741974
Clare720081967
Brooklyn619801967
Wales620181970
Scranton620101967
Pierson620181968
Rock Valley520161971
Maquoketa420241968
Washta420131967
Mt Hamill320171990
Panther320221967
Neola319871972
Alice319881967
Lafayette320122012
West Liberty220241971
Williamsburg220161986
Hudson219911971
Sioux City220081968
Festina220211968
Titonka219791979
Exline120101979
Melrose119951995

Bank Swallow Population Trend in Other States

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

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