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

Yellow-crowned Night Heron Population Trend in Illinois

All statesWetland birds

Yellow-crowned Night Heron in Illinois has fallen sharply: down 69% on the route-weighted index since 1974.

-69%Since 1974TrendPercent 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 →
6Routes 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 →
17YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Yellow-crowned Night Heron 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 declinecomputed 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 →

Yellow-crowned Night Heron has fallen sharply in Illinois: down 69% on the route-weighted index since 1974.

Yellow-crowned Night Heron Survey Routes in Illinois

Routes recording Yellow-crowned Night Heron 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 →
Chandlervill619741974
Belknap519811981
Pulaski320111971
Belleview120212021
Birds119811981
Beaverdam Lk119861972

Yellow-crowned Night Heron Population Trend in Other States

alabamaarkansasconnecticutdelawarefloridageorgiaindianakansaskentuckylouisianamarylandmississippimissourinew-jerseynew-yorknorth-carolinaohiooklahomapennsylvaniasouth-carolinatennesseetexasvirginiawest-virginia

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