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Species · Wyoming · BBS 2026 Release · 1966–2025

Brown-headed Cowbird Population Trend in Wyoming

All statesGeneralists

Brown-headed Cowbird in Wyoming has surged: up 368% on the route-weighted index since 1971.

+368%Since 1971TrendPercent 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 →
130Routes 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 →
56YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Brown-headed Cowbird Trends in WyomingNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

long arc increasecomputed indexTrend sourceWhether the figure is our own computed route-weighted index or an official USGS modeled estimate. The current build labels every trend as computed.Full methodology →

Brown-headed Cowbird has surged in Wyoming: up 368% 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 39% by 2030 — from 4.3 in 2025 to a central estimate of 5.9 (95% range 2.5–9.3). A 5-year backtest shows a typical error of ±50%, with 100% of held-out values landing inside the 95% band.

+39%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 →
5.9Projected 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 →
2.5–9.395% 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 →
±50%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, Brown-headed Cowbird in Wyoming is projected to rise about 39% by 2030 — from 4.3 in 2025 to a central estimate of 5.9 (95% range 2.5–9.3). A 5-year backtest shows a typical error of ±50%, with 100% of held-out values landing inside the 95% band.19682030
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 →
20265.72.39.1
20275.82.49.2
20285.82.49.2
20295.92.59.3
20305.92.59.3

Brown-headed Cowbird Survey Routes in Wyoming

Routes recording Brown-headed Cowbird in Wyoming.
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 →
Riverview2120251988
Upton1920251987
Meeteetse1820251995
Wilson1720251979
Schoonover1520251985
Ethete1520251991
Yoder1420251968
Mayoworth1420241982
Newcastle1320251988
Harland Flat1220251990
Rock River1220221990
Sundance1120251975
Meadowdale1120251989
Pine Bluff1120251992
Moskee 21120212003
Hayden Val1119861986
Wyarno1020251975
Nowood1020251993
Farson1020252001
Sybille Cyn1020251980
Recluse920251988
Seedskadee920231993
Colter Bay819991968
Midvale820251975
Raven820251993

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 2026-08-14.