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

Turkey Vulture Population Trend in Illinois

All statesGeneralists

Turkey Vulture in Illinois has surged: up 52× on the route-weighted index since 1972.

52×Since 1972TrendPercent 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 →
102Routes 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 →
54YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Turkey Vulture 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 →

Turkey Vulture has surged in Illinois: up 52× on the route-weighted index since 1972.

Turkey Vulture Population Forecast in Illinois

If the recent trend holds, Turkey Vulture in Illinois is projected to fall about 25% by 2029 — from 7.8 in 2024 to a central estimate of 5.9 (95% range 4.0–7.7). A 5-year backtest shows a typical error of ±27.1%, with 20% of held-out values landing inside the 95% band.

-25%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 →
5.9Projected 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 →
4.0–7.795% 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 →
±27.1%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, Turkey Vulture in Illinois is projected to fall about 25% by 2029 — from 7.8 in 2024 to a central estimate of 5.9 (95% range 4.0–7.7). A 5-year backtest shows a typical error of ±27.1%, with 20% of held-out values landing inside the 95% band.19672029
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 →
20255.43.67.2
20265.53.77.3
20275.63.87.4
20285.73.97.6
20295.94.07.7

Turkey Vulture Survey Routes in Illinois

Routes recording Turkey Vulture 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 →
Terre Haute4920241984
Belleview4920241974
Concord3520241967
Columbia3120241989
Bradbury3020241972
Royalton3020242001
Karnak2420242001
Williamsfld2220241981
Athensville2020241991
Camp Point2020241996
Eubanks2020242002
Robinson1920231976
Sandusky1820231996
Mascoutah Lk1720241999
Stillwell1620241989
Sheffield1520241988
Cave In Rock1520241993
Nilwood1420231993
Kell1420242001
Humboldt1220242002
Payson1120242000
Clayton1120242001
Geneseo1020171985
Monica1020171997
Beaverdam Lk1020231972

Turkey Vulture Population Trend in Other States

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

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