BirdAnalyst
Guild · Illinois · BBS 2026 Release · 1966–2025

Forest Birds In Illinois

All statesIllinois

58 species in this guild. As a group they are +32%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 stay roughly flat through 2030, near 5.3 (95% range 4.7–5.9). A 5-year backtest shows a typical error of ±5.6%, with 100% of held-out values landing inside the 95% band.

+2%Change by 2030TrendPercent 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 →
5.3Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
4.7–5.995% 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 →
±5.6%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 stay roughly flat through 2030, near 5.3 (95% range 4.7–5.9). A 5-year backtest shows a typical error of ±5.6%, with 100% of held-out values landing inside the 95% band.19662030
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 →
20265.24.65.8
20275.24.65.8
20285.34.75.9
20295.34.75.9
20305.34.75.9

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-billed CuckooCuculidae-93%
Black-and-white WarblerParulidae-82%
Brown ThrasherMimidae-66%
Field SparrowPasserellidae-58%
Blue JayCorvidae-52%
Red-headed WoodpeckerPicidae-50%
Cerulean WarblerParulidae-49%
Yellow-billed CuckooCuculidae-39%
OvenbirdParulidae-36%
Marsh WrenTroglodytidae-34%
Song SparrowPasserellidae-11%
Pine WarblerParulidae-9%
Hooded WarblerParulidae-8%
Baltimore OrioleIcteridae-6%
American GoldfinchFringillidae+1%
Bell's VireoVireonidae+10%
Eastern TowheePasserellidae+25%
Worm-eating WarblerParulidae+31%
Blue-winged WarblerParulidae+37%
Black-capped ChickadeeParidae+42%
Northern House WrenTroglodytidae+43%
Gray CatbirdMimidae+64%
American RedstartParulidae+72%
Northern CardinalCardinalidae+80%
Downy WoodpeckerPicidae+88%
Indigo BuntingCardinalidae+89%
American RobinTurdidae+93%
Rose-breasted GrosbeakCardinalidae+119%
Scarlet TanagerCardinalidae+120%
Eastern BluebirdTurdidae+123%
Red-eyed VireoVireonidae+124%
Hairy WoodpeckerPicidae+129%
Common YellowthroatParulidae+132%
Pileated WoodpeckerPicidae+132%
Orchard OrioleIcteridae+134%
Tufted TitmouseParidae+156%
Yellow WarblerParulidae+169%
Yellow-breasted ChatIcteriidae+170%
Wood ThrushTurdidae+173%
Warbling VireoVireonidae+175%
Prairie WarblerParulidae+206%
Kentucky WarblerParulidae+206%
Yellow-throated WarblerParulidae+217%
Prothonotary WarblerParulidae+222%
Red-bellied WoodpeckerPicidae+283%
Carolina WrenTroglodytidae+289%
Louisiana WaterthrushParulidae+398%
Carolina ChickadeeParidae+431%
White-eyed VireoVireonidae+476%
Yellow-throated VireoVireonidae+578%
White-breasted NuthatchSittidae+667%
Cedar WaxwingBombycillidae+726%
Chipping SparrowPasserellidae13×
Ruby-throated HummingbirdTrochilidae13×
Blue-gray GnatcatcherPolioptilidae18×
Northern ParulaParulidae27×
Summer TanagerCardinalidae28×
Blue GrosbeakCardinalidae46×

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.