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.

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.