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

Tree Swallow Population Trend in Iowa

All statesAerial insectivores

Tree Swallow in Iowa has surged: up 12× on the route-weighted index since 1970.

12×Since 1970
37Routes In State
53Years

Notable Tree Swallow Trends in Iowa

long arc increasecomputed index

Tree Swallow has surged in Iowa: up 12× on the route-weighted index since 1970.

Tree Swallow Population Forecast in Iowa

If the recent trend holds, Tree Swallow in Iowa is projected to stay roughly flat through 2029, near 2.6 (95% range 1.0–4.1). A 5-year backtest shows a typical error of ±63.8%, with 80% of held-out values landing inside the 95% band.

+7%Change by 2029
2.6Projected 2029 index
1.0–4.195% range
±63.8%Backtest error
19682029
Projection of the recent trend (dashed) with 80/95% bands — a projection, not a prediction. Habitat, climate, and land use are not modeled.
YearProjected index95% low95% high
20252.40.843.9
20262.40.894.0
20272.50.934.0
20282.50.984.1
20292.61.04.1

Tree Swallow Survey Routes in Iowa

Routes recording Tree Swallow in Iowa.
Prairieburg1620241968
West Liberty1120071986
Melrose1020241980
Bryant920241983
Hudson920221985
Burchinal720241995
Cedar Valley619961996
Davis Corner620191980
Exline520221980
Scranton320131978
Clare320071992
Pierson320191970
Festina320241975
Lafayette320242003
Bedford220172000
Williamsburg220221972
Desmoines219711969
Panther220151997
Maquoketa220191986
Alice219971986
Dinsdale219711971
Washta220141978
Sioux City220241981
Rock Valley220191982
College Spgs 2220212012

Tree Swallow Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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