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Species · Illinois · BBS 2026 Release · 1966–2025

Wood Duck Population Trend in Illinois

All statesWaterfowl

Wood Duck in Illinois has surged: up 75% on the route-weighted index since 1968.

+75%Since 1968TrendPercent 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 →
95Routes In StateSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
59YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Wood Duck Trends in IllinoisNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

long arc increasecomputed indexTrend sourceWhether the figure is our own computed route-weighted index or an official USGS modeled estimate. The current build labels every trend as computed.Full methodology →

Wood Duck has surged in Illinois: up 75% on the route-weighted index since 1968.

Wood Duck Population Forecast in Illinois

If the recent trend holds, Wood Duck in Illinois is projected to fall about 23% by 2030 — from 0.67 in 2025 to a central estimate of 0.52 (95% range 0.00–1.0). A 5-year backtest shows a typical error of ±44.4%, with 100% of held-out values landing inside the 95% band.

-23%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 →
0.52Projected 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 →
0.00–1.095% 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 →
±44.4%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, Wood Duck in Illinois is projected to fall about 23% by 2030 — from 0.67 in 2025 to a central estimate of 0.52 (95% range 0.00–1.0). A 5-year backtest shows a typical error of ±44.4%, 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 →
20260.520.001.0
20270.520.001.0
20280.520.001.0
20290.520.001.0
20300.520.001.0

Wood Duck Survey Routes in Illinois

Routes recording Wood Duck in Illinois.
Recent countThe raw number of individuals recorded on this route in its most recent survey year. A single-route tally, not a trend.Full methodology →
Belleview1720251966
Beaucoup1120251992
Stillwell820171991
Atkinson719991996
Essex519951995
Troy Grove520151993
Streator420221991
Gulfport420231971
Seneca420211993
Clayton420192009
Fairdale420252021
Geneseo320181969
Sherburnvill320231999
Pawnee320251972
Flora320241976
Belknap320231975
Mill Creek220061975
Wayne220251977
Terre Haute220241971
Cameron220232017
Bartonville220191989
Monica220191982
Deer Creek220151985
Pontiac220121979
Bluff Spgs220111975

Wood Duck Population Trend in Other States

alabamaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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