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

Tree Swallow Population Trend in Illinois

All statesAerial insectivores

Tree Swallow in Illinois has surged: up 140% on the route-weighted index since 1969.

+140%Since 1969
99Routes In State
57Years

Notable Tree Swallow Trends in Illinois

long arc increasecomputed index

Tree Swallow has surged in Illinois: up 140% on the route-weighted index since 1969.

Tree Swallow Population Forecast in Illinois

If the recent trend holds, Tree Swallow in Illinois is projected to stay roughly flat through 2029, near 2.2 (95% range 1.0–3.5). A 5-year backtest shows a typical error of ±45.1%, with 80% of held-out values landing inside the 95% band.

+8%Change by 2029
2.2Projected 2029 index
1.0–3.595% range
±45.1%Backtest error
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 index95% low95% high
20252.10.893.3
20262.10.933.3
20272.20.963.4
20282.21.003.4
20292.21.03.5

Tree Swallow Survey Routes in Illinois

Routes recording Tree Swallow in Illinois.
Brnt Prairie1720241994
Geneseo1520181970
Janesville1420242005
Seneca1320241998
Fairbury1220242010
Streator1020241974
Gridley1020242009
Le Roy820241993
Holcomb720231973
Wayne720241974
Essex620241991
Humphrey620241982
Atkinson520241987
Gulfport520241984
Deer Creek520211992
Lake Summerset520222001
Yorkville520102009
Karnak520242002
Barrington420111970
Milford420231989
Belleview420241982
Fairdale420242024
Cherry Val320011976
Bartonville320241973
Minonk320241991

Tree Swallow Population Trend in Other States

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

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