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Species · Illinois · BBS 2026 Release · 1966–2025

Louisiana Waterthrush Population Trend in Illinois

All statesForest birds

Louisiana Waterthrush in Illinois has surged: up 398% on the route-weighted index since 1984.

+398%Since 1984TrendPercent 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 →
26Routes 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 →
39YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Louisiana Waterthrush 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 Louisiana Waterthrush in Illinois. See the full index history below.

Louisiana Waterthrush Population Forecast in Illinois

If the recent trend holds, Louisiana Waterthrush in Illinois is projected to fall about 48% by 2030 — from 0.19 in 2025 to a central estimate of 0.10 (95% range 0.03–0.17). A 5-year backtest shows a typical error of ±26.1%, with 80% of held-out values landing inside the 95% band.

-48%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 →
0.10Projected 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 →
0.03–0.1795% 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 →
±26.1%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, Louisiana Waterthrush in Illinois is projected to fall about 48% by 2030 — from 0.19 in 2025 to a central estimate of 0.10 (95% range 0.03–0.17). A 5-year backtest shows a typical error of ±26.1%, with 80% of held-out values landing inside the 95% band.19712030
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 →
20260.090.030.16
20270.090.030.16
20280.100.030.16
20290.100.030.16
20300.100.030.17

Louisiana Waterthrush Survey Routes in Illinois

Routes recording Louisiana Waterthrush 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 →
Belleview720251995
Payson220252000
Columbia220172001
Cave In Rock220231997
Bartonville120222022
Melrose119981990
Athensville119841984
Concord120142011
Clarksdale119711971
Mascoutah Lk120052005
Clayton120162016
Brnt Prairie120182018
Grape Creek120132008
Eubanks120222003
Pulaski120242018
Bremen120251989
Belknap120252005
Delwood120251984
Beaverdam Lk120161972
Marshall120152015
Dudleyville120182018
Kell120132002
Karnak120252025
Camp Point120252001
Eldred120092009

Louisiana Waterthrush Population Trend in Other States

alabamaarkansasconnecticutdelawarefloridageorgiaindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourinew-hampshirenew-jerseynew-yorknorth-carolinaohiooklahomapennsylvaniarhode-islandsouth-carolinatennesseetexasvermontvirginiawest-virginiawisconsin

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