BirdAnalyst
Species · South Dakota · BBS 2026 Release · 1966–2025

Brown-headed Cowbird Population Trend in South Dakota

All statesGeneralists

Brown-headed Cowbird in South Dakota has increased: up 46% on the route-weighted index since 1969.

+46%Since 1969TrendPercent 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 →
65Routes 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 →
58YearsYears 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 South DakotaNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

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

Brown-headed Cowbird Population Forecast in South Dakota

If the recent trend holds, Brown-headed Cowbird in South Dakota is projected to fall about 11% by 2030 — from 56 in 2025 to a central estimate of 50 (95% range 33–68). A 5-year backtest shows a typical error of ±16.8%, with 100% of held-out values landing inside the 95% band.

-11%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 →
50Projected 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 →
33–6895% 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 →
±16.8%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 South Dakota is projected to fall about 11% by 2030 — from 56 in 2025 to a central estimate of 50 (95% range 33–68). A 5-year backtest shows a typical error of ±16.8%, with 100% of held-out values landing inside the 95% band.19672030
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 →
2026493267
2027503267
2028503267
2029503268
2030503368

Brown-headed Cowbird Survey Routes in South Dakota

Routes recording Brown-headed Cowbird in South Dakota.
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 →
Volunteer28120251967
Ft Thompson19420111967
Promise15420151971
White Lake12320111967
Rockyford12320251968
Rosebud11820111967
Crow Creek10820231967
Forbes10220251967
Conde10119841967
Lodgepole9720251990
Cedar Pass9320251967
Fort Pierre9020251968
Maurine8520251968
Isabel8320151990
Reva8220251987
Gettysburg8120231969
Ottumwa7920251967
Tripp7720251967
Howard7620251970
Owanka7520221967
Roswell7420141967
Raymond6720211967
Eagle Butte6720151990
Lane6319991967
Marcus6220151999

Brown-headed Cowbird Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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