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

Cliff Swallow Population Trend in Iowa

All statesAerial insectivores

Cliff Swallow in Iowa has surged: up 28× on the route-weighted index since 1970.

28×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 →
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 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 28× 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 stay roughly flat through 2029, near 27 (95% range 19–35). A 5-year backtest shows a typical error of ±14.9%, with 100% 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 →
27Projected 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 →
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 →
±14.9%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, Cliff Swallow in Iowa is projected to stay roughly flat through 2029, near 27 (95% range 19–35). A 5-year backtest shows a typical error of ±14.9%, 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 →
2025251733
2026251733
2027261834
2028261834
2029271935

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 →
Festina16720241970
Alice7919991985
West Liberty6920241985
Wales4520181967
Scranton3820241982
Melrose3720241981
Washta3720141968
Mccallsburg3720241996
Kanawha3220241985
Bryant3020241984
Davis Corner3020241974
Washington2720241973
Panther2620241977
Sioux City2520221989
Lafayette2520242003
Dinsdale2220241971
Burchinal2020241995
Tipton1920241993
Red Rock1720241974
Gaza1720231989
College Spgs 21720232006
Pierson1520191987
Rock Valley1520241972
Prairieburg1320191975
Exline1220241983

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 2026-05-22.