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

Mallard Population Trend in Illinois

All statesWaterfowl

Mallard in Illinois has surged: up 249% on the route-weighted index since 1968.

+249%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 →
100Routes 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 →
58YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Mallard 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 →

Mallard has surged in Illinois: up 249% on the route-weighted index since 1968.

Mallard Population Forecast in Illinois

If the recent trend holds, Mallard in Illinois is projected to rise about 46% by 2029 — from 1.0 in 2024 to a central estimate of 1.5 (95% range 0.00–3.2). A 5-year backtest shows a typical error of ±86.3%, with 100% of held-out values landing inside the 95% band.

+46%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 →
1.5Projected 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 →
0.00–3.295% 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 →
±86.3%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, Mallard in Illinois is projected to rise about 46% by 2029 — from 1.0 in 2024 to a central estimate of 1.5 (95% range 0.00–3.2). A 5-year backtest shows a typical error of ±86.3%, with 100% 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 →
20251.50.003.2
20261.50.003.2
20271.50.003.2
20281.50.003.2
20291.50.003.2

Mallard Survey Routes in Illinois

Routes recording Mallard 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 →
Yorkville12020182001
Putnam6520171975
New Lenox5720191966
Sherburnvill1720221967
Itasca1620241973
Wayne1420241967
Seneca1320241993
Minonk1220241973
Keithsburg920192002
Guilford620211968
Beaverdam Lk619981984
Troy Grove620191993
Union620172011
Cherry Val520031972
Birds520221992
Barrington420111970
Geneseo420181971
Monticello420211980
Fairbury420161985
Pontiac420241978
Milford420091992
Waynesville420132001
Mill Creek320091972
Terre Haute320211979
Williamsfld320191971

Mallard Population Trend in Other States

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

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