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

Wetland Birds In Illinois

All statesIllinois

13 species in this guild. As a group they are +61%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 wetland birds in Illinois. See the full index history below.

Wetland Birds In Illinois Population Forecast

If the recent trend holds, Wetland birds in Illinois is projected to rise about 103% by 2029 — from 0.35 in 2024 to a central estimate of 0.71 (95% range 0.38–1.1). A 5-year backtest shows a typical error of ±68.8%, with 60% of held-out values landing inside the 95% band.

+103%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 →
0.71Projected 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 →
0.38–1.195% 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 →
±68.8%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, Wetland birds in Illinois is projected to rise about 103% by 2029 — from 0.35 in 2024 to a central estimate of 0.71 (95% range 0.38–1.1). A 5-year backtest shows a typical error of ±68.8%, 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 →
20250.690.351.0
20260.690.361.0
20270.700.361.0
20280.710.371.0
20290.710.381.1

Member Species In Illinois

Wetland 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 →
American CootRallidae-96%
Western Cattle-EgretArdeidae-94%
Little Blue HeronArdeidae-86%
Pied-billed GrebePodicipedidae-83%
Yellow-crowned Night HeronArdeidae-69%
Black-crowned Night HeronArdeidae-34%
Green HeronArdeidae-27%
Sandhill CraneGruidae+15%
Great EgretArdeidae+33%
Herring GullLaridae+120%
Great Blue HeronArdeidae+257%
Ring-billed GullLaridae+283%
Double-crested CormorantPhalacrocoracidae+721%

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