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

Brown-headed Cowbird Population Trend in Wyoming

All statesGeneralists

Brown-headed Cowbird in Wyoming has surged: up 388% on the route-weighted index since 1971.

+388%Since 1971
130Routes In State
55Years

Notable Brown-headed Cowbird Trends in Wyoming

long arc increasecomputed index

Brown-headed Cowbird has surged in Wyoming: up 388% on the route-weighted index since 1971.

Brown-headed Cowbird Population Forecast in Wyoming

If the recent trend holds, Brown-headed Cowbird in Wyoming is projected to rise about 33% by 2029 — from 4.5 in 2024 to a central estimate of 6.0 (95% range 2.6–9.4). A 5-year backtest shows a typical error of ±61.8%, with 100% of held-out values landing inside the 95% band.

+33%Change by 2029
6.0Projected 2029 index
2.6–9.495% range
±61.8%Backtest error
19682029
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
20255.82.49.2
20265.82.49.2
20275.92.59.3
20285.92.59.3
20296.02.69.4

Brown-headed Cowbird Survey Routes in Wyoming

Routes recording Brown-headed Cowbird in Wyoming.
Upton3920241987
Yoder3320241968
Midvale2520221975
Schoonover2520241985
Arvada2520241988
Recluse2320241988
Wyarno2220241975
Shawnee1720241988
Newcastle1620241988
Mayoworth1420241982
Sussex1320241991
Rock River1220221990
Moskee 21120212003
Hayden Val1119861986
Farson1020242001
Seedskadee920231993
Colter Bay 2920242021
Colter Bay819991968
Ethete820241991
Sybille Cyn820241980
Sundance720241975
Fontenelle720241982
Seely720001990
Green River719841984
Harmony720231980

Brown-headed Cowbird Population Trend in Other States

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

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