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Species · Wisconsin · BBS 2025 Release · 1966–2024

Brown-headed Cowbird Population Trend in Wisconsin

All statesGeneralists

Brown-headed Cowbird in Wisconsin has declined: down 43% on the route-weighted index since 1968.

-43%Since 1968
98Routes In State
58Years

Notable Brown-headed Cowbird Trends in Wisconsin

No notable trend signals for Brown-headed Cowbird in Wisconsin. See the full index history below.

Brown-headed Cowbird Population Forecast in Wisconsin

If the recent trend holds, Brown-headed Cowbird in Wisconsin is projected to fall about 15% by 2029 — from 12 in 2024 to a central estimate of 10 (95% range 6.6–14). A 5-year backtest shows a typical error of ±9%, with 100% of held-out values landing inside the 95% band.

-15%Change by 2029
10Projected 2029 index
6.6–1495% range
±9%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
2025117.315
2026117.115
2027117.015
2028116.814
2029106.614

Brown-headed Cowbird Survey Routes in Wisconsin

Routes recording Brown-headed Cowbird in Wisconsin.
Grimms9620211998
Pardeeville5420241967
Annaton4820241998
Pt Washingtn4320241966
Paris4120241966
Hebron3620241966
Raymond3620241966
River Falls3520241998
Kiel3520221998
Weyerhauser3320241966
Cumberland3220241966
Hazel Green3020241966
Cadott2920241966
Holland2920241998
Stratford2820241966
Fall River2820241966
Omro2620011966
Union Twp2320241966
Dresser2220241966
Wiota2120241966
Holway2019891967
Saxeville2020241966
Mukwonago 22020242005
N Andover1920241967
Mukwonago1920041998

Brown-headed Cowbird Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawyoming

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