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

Forest Birds In Illinois

All statesIllinois

37 species in this guild. As a group they are +42%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 forest birds in Illinois. See the full index history below.

Forecast

If the recent trend holds, Forest birds in Illinois is projected to rise about 12% by 2029 — from 4.2 in 2024 to a central estimate of 4.6 (95% range 4.1–5.2). A 5-year backtest shows a typical error of ±11.3%, with 60% of held-out values landing inside the 95% band.

+12%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 →
4.1–5.295% 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 →
±11.3%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, Forest birds in Illinois is projected to rise about 12% by 2029 — from 4.2 in 2024 to a central estimate of 4.6 (95% range 4.1–5.2). A 5-year backtest shows a typical error of ±11.3%, with 60% 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 →
20254.54.05.0
20264.54.05.1
20274.64.15.1
20284.64.15.1
20294.64.15.2

Member Species In Illinois

Forest birds 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 →
Black-and-white WarblerParulidae-83%
Marsh WrenTroglodytidae-76%
Red-headed WoodpeckerPicidae-56%
OvenbirdParulidae-41%
Cerulean WarblerParulidae-41%
Pine WarblerParulidae-19%
Bell's VireoVireonidae+9%
Black-capped ChickadeeParidae+28%
Hooded WarblerParulidae+34%
Blue-winged WarblerParulidae+37%
Northern House WrenTroglodytidae+46%
Worm-eating WarblerParulidae+63%
American RedstartParulidae+74%
Eastern BluebirdTurdidae+81%
American RobinTurdidae+84%
Downy WoodpeckerPicidae+92%
Yellow WarblerParulidae+114%
Common YellowthroatParulidae+122%
Red-eyed VireoVireonidae+131%
Hairy WoodpeckerPicidae+136%
Pileated WoodpeckerPicidae+145%
Tufted TitmouseParidae+154%
Warbling VireoVireonidae+155%
Wood ThrushTurdidae+183%
Prairie WarblerParulidae+194%
Carolina WrenTroglodytidae+196%
Kentucky WarblerParulidae+224%
Prothonotary WarblerParulidae+234%
Louisiana WaterthrushParulidae+239%
Red-bellied WoodpeckerPicidae+257%
Yellow-throated WarblerParulidae+267%
Carolina ChickadeeParidae+411%
White-eyed VireoVireonidae+554%
Yellow-throated VireoVireonidae+619%
White-breasted NuthatchSittidae+688%
Blue-gray GnatcatcherPolioptilidae18×
Northern ParulaParulidae27×

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