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

Waterfowl In Illinois

All statesIllinois

5 species in this guild. As a group they are 16×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 waterfowl in Illinois. See the full index history below.

Waterfowl In Illinois Population Forecast

If the recent trend holds, Waterfowl in Illinois is projected to fall about 35% by 2030 — from 4.8 in 2025 to a central estimate of 3.2 (95% range 2.0–4.3). A 5-year backtest shows a typical error of ±31.5%, with 80% of held-out values landing inside the 95% band.

-35%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 →
3.2Projected 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 →
2.0–4.395% 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 →
±31.5%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, Waterfowl in Illinois is projected to fall about 35% by 2030 — from 4.8 in 2025 to a central estimate of 3.2 (95% range 2.0–4.3). A 5-year backtest shows a typical error of ±31.5%, with 80% 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 →
20263.01.84.2
20273.01.94.2
20283.11.94.2
20293.11.94.3
20303.22.04.3

Member Species In Illinois

Waterfowl 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 →
Blue-winged TealAnatidae-80%
Hooded MerganserAnatidae-60%
Wood DuckAnatidae+75%
MallardAnatidae+208%
Canada GooseAnatidae27×

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