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

Double-crested Cormorant Population Trend in South Dakota

All statesWetland birds

Double-crested Cormorant in South Dakota has fallen sharply: down 51% on the route-weighted index since 1969.

-51%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 →
34Routes 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 Double-crested Cormorant 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 →

Double-crested Cormorant has fallen sharply in South Dakota: down 51% on the route-weighted index since 1969.

Double-crested Cormorant Population Forecast in South Dakota

If the recent trend holds, Double-crested Cormorant in South Dakota is projected to rise about 207% by 2030 — from 0.61 in 2025 to a central estimate of 1.9 (95% range 0.00–4.1). A 5-year backtest shows a typical error of ±255.6%, with 100% of held-out values landing inside the 95% band.

+207%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 →
1.9Projected 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 →
0.00–4.195% 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 →
±255.6%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, Double-crested Cormorant in South Dakota is projected to rise about 207% by 2030 — from 0.61 in 2025 to a central estimate of 1.9 (95% range 0.00–4.1). A 5-year backtest shows a typical error of ±255.6%, 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 →
20261.80.004.0
20271.80.004.0
20281.80.004.1
20291.80.004.1
20301.90.004.1

Double-crested Cormorant Survey Routes in South Dakota

Routes recording Double-crested Cormorant 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 →
Raymond1320211983
Roswell1120141985
Hayes920011992
Lacreek920221994
Turton820082008
Volga620251992
Forbes620251979
Ardmore620151994
White Lake520111968
Geddes520231968
Chamberlain520111967
Ft Thompson520111969
Britton520231971
Long Lake520191977
Broadland420122000
Winner320252025
Laplant319991971
S. Pioneer220221997
Crow Creek220191973
Conde219671967
Gorman219931993
Lodgepole220192019
Indian220002000
Lennox120092005
Tripp120092009

Double-crested Cormorant 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.