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

Aerial Insectivores In Illinois

All statesIllinois

17 species in this guild. As a group they are +24%Guild trendA mean-index aggregate across the species in this group — the structural direction of the guild, with individual-species noise smoothed out.Full methodology → since 1968.

Guild SignalsNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

No notable trend signals for aerial insectivores in Illinois. See the full index history below.

Aerial Insectivores In Illinois Population Forecast

If the recent trend holds, Aerial insectivores in Illinois is projected to fall about 19% by 2029 — from 5.7 in 2024 to a central estimate of 4.6 (95% range 3.7–5.5). A 5-year backtest shows a typical error of ±14%, with 80% of held-out values landing inside the 95% band.

-19%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 →
4.6Projected 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 →
3.7–5.595% 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 →
±14%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, Aerial insectivores in Illinois is projected to fall about 19% by 2029 — from 5.7 in 2024 to a central estimate of 4.6 (95% range 3.7–5.5). A 5-year backtest shows a typical error of ±14%, with 80% of held-out values landing inside the 95% band.19662029
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 →
20254.63.75.5
20264.63.75.5
20274.63.75.5
20284.63.75.5
20294.63.75.5

Member Species In Illinois

Aerial insectivores species in Illinois.
TrendPercent 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 →
Bank SwallowHirundinidae-95%
Least FlycatcherTyrannidae-82%
Chuck-will's-widowCaprimulgidae-77%
Eastern Whip-poor-willCaprimulgidae-68%
Chimney SwiftApodidae-66%
Purple MartinHirundinidae-44%
Common NighthawkCaprimulgidae-27%
Eastern KingbirdTyrannidae-8%
Willow FlycatcherTyrannidae+5%
Barn SwallowHirundinidae+10%
Great Crested FlycatcherTyrannidae+122%
Tree SwallowHirundinidae+140%
Eastern Wood-PeweeTyrannidae+203%
Eastern PhoebeTyrannidae+378%
Acadian FlycatcherTyrannidae+447%
Northern Rough-winged SwallowHirundinidae+458%
Cliff SwallowHirundinidae179×

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