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

Redhead Population Trend in South Dakota

All statesWaterfowl

Redhead in South Dakota has fallen sharply: down 66% on the route-weighted index since 1969.

-66%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 →
32Routes 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 Redhead 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 declinecomputed 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 →

Redhead has fallen sharply in South Dakota: down 66% on the route-weighted index since 1969.

Redhead Population Forecast in South Dakota

If the recent trend holds, Redhead in South Dakota is projected to fall about 24% by 2029 — from 0.82 in 2024 to a central estimate of 0.62 (95% range 0.00–3.2). A 5-year backtest shows a typical error of ±38.6%, 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 →
0.62Projected 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 →
0.00–3.295% 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 →
±38.6%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, Redhead in South Dakota is projected to fall about 24% by 2029 — from 0.82 in 2024 to a central estimate of 0.62 (95% range 0.00–3.2). A 5-year backtest shows a typical error of ±38.6%, 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 →
20250.690.003.2
20260.670.003.2
20270.660.003.2
20280.640.003.2
20290.620.003.2

Redhead Survey Routes in South Dakota

Routes recording Redhead 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 →
Raymond2020211984
Turton2020192019
Forbes1020241967
White Lake920111967
Lacreek920232019
Long Lake820191967
Ottumwa819981998
Veblen720191967
Conde619841967
Cedar Pass619961975
Ardmore520191983
Volga420241969
Britton420221967
Gettysburg420231993
Hayes420082008
Lennox320081969
Pioneer319971993
Lodgepole320102010
Howard220181983
Chamberlain220112010
Cottonwood220241995
Roswell220111967
S. Pioneer220171995
Crow Creek220191973
Wilmot220241969

Redhead Population Trend in Other States

alaskaarizonacaliforniacoloradoidahoiowakansasmichiganminnesotamontananebraskanevadanew-mexiconew-yorknorth-dakotaoklahomaoregontexasutahwashingtonwisconsinwyoming

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22.