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

Cliff Swallow Population Trend in Iowa

All statesAerial insectivores

Cliff Swallow in Iowa has surged: up 25× on the route-weighted index since 1970.

25×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 →
37Routes 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 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 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 →

Cliff Swallow has surged in Iowa: up 25× on the route-weighted index since 1970.

Cliff Swallow Population Forecast in Iowa

If the recent trend holds, Cliff Swallow in Iowa is projected to rise about 36% by 2030 — from 20 in 2025 to a central estimate of 27 (95% range 19–35). A 5-year backtest shows a typical error of ±15.7%, with 100% of held-out values landing inside the 95% band.

+36%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 →
27Projected 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 →
19–3595% 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 →
±15.7%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, Cliff Swallow in Iowa is projected to rise about 36% by 2030 — from 20 in 2025 to a central estimate of 27 (95% range 19–35). A 5-year backtest shows a typical error of ±15.7%, with 100% of held-out values landing inside the 95% band.19672030
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 →
2026251733
2027251734
2028261834
2029261835
2030271935

Cliff Swallow Survey Routes in Iowa

Routes recording Cliff 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 →
Alice7919991985
Titonka7820251991
Melrose7120251981
Kanawha6320251985
Exline5520251983
Washta5520251968
Festina4520251970
Brooklyn3720251985
Tipton3320251993
Mccallsburg2920251996
West Liberty2620251985
Dinsdale2620251971
Sioux City2520221989
Washington2220251973
Gaza1920251989
Pierson1520191987
Scranton1420251982
Prairieburg1320191975
Burchinal920251995
Rock Valley820251972
Neola620161992
College Spgs 2520252006
Mt Hamill420122012
Lafayette420252003
Williamsburg320231981

Cliff Swallow Population Trend in Other States

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

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.