BirdAnalyst
Species · South Dakota · BBS 2025 Release · 1966–2024

Brown-headed Cowbird Population Trend in South Dakota

All statesGeneralists

Brown-headed Cowbird in South Dakota has increased: up 32% on the route-weighted index since 1969.

+32%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 →
57YearsYears 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 rise about 24% by 2029 — from 40 in 2024 to a central estimate of 49 (95% range 32–67). A 5-year backtest shows a typical error of ±15.3%, with 100% of held-out values landing inside the 95% band.

+24%Change by 2029TrendPercent 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 →
49Projected 2029 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
32–6795% 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 →
±15.3%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 rise about 24% by 2029 — from 40 in 2024 to a central estimate of 49 (95% range 32–67). A 5-year backtest shows a typical error of ±15.3%, with 100% of held-out values landing inside the 95% band.19672029
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 →
2025493166
2026493166
2027493167
2028493267
2029493267

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 →
Ft Thompson19420111967
Maurine16020241968
Promise15420151971
White Lake12320111967
Rosebud11820111967
Crow Creek10820231967
Conde10119841967
Forbes9720241967
Isabel8320151990
Gettysburg8120231969
Owanka7520221967
Roswell7420141967
Ottumwa6820221967
Raymond6720211967
Eagle Butte6720151990
Tripp6620241967
Lane6319991967
Marcus6220151999
Fort Pierre6120241968
Chamberlain5920111967
Long Lake5920191967
Volunteer5920191967
Railroad Butte5920221995
Laplant5720151971
Lodgepole5720241990

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 2026-05-22.