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.

Forest Birds In Illinois Population 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.