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

Black-headed Grosbeak Population Trend in South Dakota

All statesForest birds

Black-headed Grosbeak in South Dakota has surged: up 871% on the route-weighted index since 1969.

+871%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 →
42Routes 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 Black-headed Grosbeak 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 →

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 →

Black-headed Grosbeak has surged in South Dakota: up 871% on the route-weighted index since 1969.

Black-headed Grosbeak Population Forecast in South Dakota

If the recent trend holds, Black-headed Grosbeak in South Dakota is projected to fall about 40% by 2030 — from 1.1 in 2025 to a central estimate of 0.67 (95% range 0.39–0.94). A 5-year backtest shows a typical error of ±26.3%, with 80% of held-out values landing inside the 95% band.

-40%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 →
0.67Projected 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 →
0.39–0.9495% 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 →
±26.3%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, Black-headed Grosbeak in South Dakota is projected to fall about 40% by 2030 — from 1.1 in 2025 to a central estimate of 0.67 (95% range 0.39–0.94). A 5-year backtest shows a typical error of ±26.3%, with 80% 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 →
20260.630.350.91
20270.640.360.92
20280.650.370.93
20290.660.380.94
20300.670.390.94

Black-headed Grosbeak Survey Routes in South Dakota

Routes recording Black-headed Grosbeak 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 →
Hazelrodt920251992
Long Draw620251992
Custer520251973
Rochford420251993
Silver City420121994
Railroad Butte320042001
Wind Cave Np320252000
Badlands320031990
Chamberlain220111971
Ft Thompson219691969
Volunteer220251967
Harding220042004
Cedar Pass220021968
Elk Mountain220011999
Geddes119671967
Winner120131988
Rosebud119891989
Rockyford120251968
Indian120222022
French Creek120041996
Laplant119861971
Promise120131971
Owanka120101994
Roubaix Lk119911969
Ottumwa120102003

Black-headed Grosbeak Population Trend in Other States

alaskaarizonacaliforniacoloradoidahokansasmontananebraskanevadanew-mexiconorth-dakotaoklahomaoregontexasutahwashingtonwyoming

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