BirdAnalyst
Species · Nevada · BBS 2026 Release · 1966–2025

Brown-headed Cowbird Population Trend in Nevada

All statesGeneralists

Brown-headed Cowbird in Nevada has surged: up 367% on the route-weighted index since 1970.

+367%Since 1970TrendPercent 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 →
48Routes 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 →
52YearsYears 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 NevadaNotable 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 Nevada: up 367% on the route-weighted index since 1970.

Brown-headed Cowbird Population Forecast in Nevada

If the recent trend holds, Brown-headed Cowbird in Nevada is projected to fall about 25% by 2030 — from 4.6 in 2025 to a central estimate of 3.5 (95% range 0.54–6.4). A 5-year backtest shows a typical error of ±108.5%, with 100% of held-out values landing inside the 95% band.

-25%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 →
3.5Projected 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 →
0.54–6.495% 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 →
±108.5%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 Nevada is projected to fall about 25% by 2030 — from 4.6 in 2025 to a central estimate of 3.5 (95% range 0.54–6.4). A 5-year backtest shows a typical error of ±108.5%, 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 →
20263.30.406.2
20273.40.436.3
20283.40.476.3
20293.40.516.4
20303.50.546.4

Brown-headed Cowbird Survey Routes in Nevada

Routes recording Brown-headed Cowbird in Nevada.
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 →
Gardnerville 24820252013
Ruby Valley2420011997
Gardnerville1920121992
Willis1920251988
Sand Pass1120251987
Ash Meadows1120231993
Hawthorne919991997
Ranchogrande820241990
Oreana820032002
Jean Lake719911991
Carson River720052001
Chimney Res.720232005
Piute Mdws520252013
Cortez520231969
Walker Can520121970
Toiyabe Nf520242002
Jarbidge520062006
Fish Creek420181997
Hiko420251968
Virgin Creek420181995
Midas320251990
Dinner Sta319931969
Rye Patch319711970
Sutcliffe319701970
Minerva320151988

Brown-headed Cowbird Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.