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

Brown Thrasher Population Trend in Illinois

All statesGeneralists

Brown Thrasher in Illinois has fallen sharply: down 67% on the route-weighted index since 1968.

-67%Since 1968
105Routes In State
58Years

Notable Brown Thrasher Trends in Illinois

long arc declinecomputed index

Brown Thrasher has fallen sharply in Illinois: down 67% on the route-weighted index since 1968.

Brown Thrasher Population Forecast in Illinois

If the recent trend holds, Brown Thrasher in Illinois is projected to fall about 16% by 2029 — from 2.8 in 2024 to a central estimate of 2.4 (95% range 0.78–4.0). A 5-year backtest shows a typical error of ±5.3%, with 100% of held-out values landing inside the 95% band.

-16%Change by 2029
2.4Projected 2029 index
0.78–4.095% range
±5.3%Backtest error
19662029
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
20252.71.14.3
20262.61.04.2
20272.60.964.2
20282.50.874.1
20292.40.784.0

Brown Thrasher Survey Routes in Illinois

Routes recording Brown Thrasher in Illinois.
Flora1420221976
Belleview1320241966
Athensville1020241971
Bremen1020241969
Payson1020242000
Mascoutah Lk820241967
Kell820242001
St Morgan720221967
Seneca720241993
Darmstadt720241993
Buda620231977
Chandlervill620241971
Melrose619991973
Birds620221976
Belknap620241970
Delwood620241970
Clayton620242001
Eubanks620242001
Marshall620242001
Terre Haute520241966
Cameron520241966
Beaverdam Lk520231970
York520241993
Newark420221969
Monticello420231976

Brown Thrasher Population Trend in Other States

alabamaarkansascoloradoconnecticutdelawarefloridageorgiaindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasvermontvirginiawest-virginiawisconsinwyoming

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