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Species · Illinois · BBS 2025 Release · 1966–2024

Worm-eating Warbler Population Trend in Illinois

All statesForest birds

Worm-eating Warbler in Illinois has risen sharply: up 63% on the route-weighted index since 1983.

+63%Since 1983
12Routes In State
38Years

Notable Worm-eating Warbler Trends in Illinois

No notable trend signals for Worm-eating Warbler in Illinois. See the full index history below.

Worm-eating Warbler Population Forecast in Illinois

If the recent trend holds, Worm-eating Warbler in Illinois is projected to stay roughly flat through 2029, near 0.05 (95% range 0.01–0.09). A 5-year backtest shows a typical error of ±64.1%, with 100% of held-out values landing inside the 95% band.

n/aChange by 2029
0.05Projected 2029 index
0.01–0.0995% range
±64.1%Backtest error
19782029
Projection of the recent trend (dashed) with 80/95% bands — a projection, not a prediction. Habitat, climate, and land use are not modeled.
YearProjected index95% low95% high
20250.050.010.09
20260.050.010.09
20270.050.010.09
20280.050.010.09
20290.050.010.09

Worm-eating Warbler Survey Routes in Illinois

Routes recording Worm-eating Warbler in Illinois.
Guilford119901989
Athens120222022
Payson120162016
Nilwood120142014
Sandusky120231993
Cave In Rock120232004
Marshall120162016
Eubanks120102007
Pulaski120172017
Bremen120231998
Delwood120241978
Karnak120162016

Worm-eating Warbler Population Trend in Other States

alabamaarkansasconnecticutdelawaregeorgiaindianaiowakentuckylouisianamarylandmassachusettsmississippimissourinew-hampshirenew-jerseynew-yorknorth-carolinaohiooklahomapennsylvaniarhode-islandsouth-carolinatennesseetexasvirginiawest-virginiawisconsin

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