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

Common Nighthawk Population Trend in Illinois

All statesAerial insectivores

Common Nighthawk in Illinois has declined: down 27% on the route-weighted index since 1969.

-27%Since 1969TrendPercent 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 →
56Routes 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 →
57YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Common Nighthawk 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 →

No notable trend signals for Common Nighthawk in Illinois. See the full index history below.

Common Nighthawk Population Forecast in Illinois

If the recent trend holds, Common Nighthawk in Illinois is projected to stay roughly flat through 2029, near 0.03 (95% range 0.00–0.13). A 5-year backtest shows a typical error of ±58.8%, with 100% of held-out values landing inside the 95% band.

n/aChange 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 →
0.03Projected 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 →
0.00–0.1395% 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 →
±58.8%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, Common Nighthawk in Illinois is projected to stay roughly flat through 2029, near 0.03 (95% range 0.00–0.13). A 5-year backtest shows a typical error of ±58.8%, with 100% 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 →
20250.040.000.13
20260.030.000.13
20270.030.000.13
20280.030.000.13
20290.030.000.13

Common Nighthawk Survey Routes in Illinois

Routes recording Common Nighthawk 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 →
Mascoutah Lk420221982
Cherry Val319911991
Sherburnvill320162016
Gridley320102006
Athens220012001
Geneseo220031969
New Lenox219891989
Bartonville220031974
Deer Creek219681968
Bradbury219751975
Seneca220241994
Mill Creek119911991
Holcomb119901988
Barrington119971978
Itasca120051971
Putnam119861986
Sheffield119871968
Compton119851973
Streator120062005
Wayne119731973
Essex119991999
Newark119831983
Gulfport120242001
Stillwell120082008
Chandlervill119761972

Common Nighthawk 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.