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

Black Tern Population Trend in South Dakota

All statesWetland birds

Black Tern in South Dakota has collapsed: down 84% on the route-weighted index since 1969.

-84%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 →
28Routes 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 →
53YearsYears 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 Tern 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 →

Black Tern has collapsed in South Dakota: down 84% on the route-weighted index since 1969.

Black Tern Population Forecast in South Dakota

If the recent trend holds, Black Tern in South Dakota is projected to fall about 70% by 2028 — from 0.67 in 2023 to a central estimate of 0.20 (95% range 0.00–2.5). A 5-year backtest shows a typical error of ±87.4%, with 80% of held-out values landing inside the 95% band.

-70%Change by 2028TrendPercent 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 →
0.20Projected 2028 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–2.595% 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 →
±87.4%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 Tern in South Dakota is projected to fall about 70% by 2028 — from 0.67 in 2023 to a central estimate of 0.20 (95% range 0.00–2.5). A 5-year backtest shows a typical error of ±87.4%, with 80% of held-out values landing inside the 95% band.19672028
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 →
20240.320.002.6
20250.290.002.6
20260.260.002.6
20270.230.002.5
20280.200.002.5

Black Tern Survey Routes in South Dakota

Routes recording Black Tern 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 →
White Lake3820111967
Howard2420081970
Long Lake2420191967
Lacreek1320192019
Forbes1120231967
Cottonwood920091994
Volga920191967
Owanka720141967
Lennox620051976
Gettysburg520231969
Raymond420211967
Conde419671967
Harding319821967
Gorman319981995
Tripp220081988
Lane219851977
Wilmot220191967
Veblen220231967
Laplant219781978
Turton220231985
Pioneer119951995
Chamberlain119681968
Roswell120081967
Broadland120121978
Crow Creek120221969

Black Tern Population Trend in Other States

californiacoloradoidahoillinoisindianaiowakansasmainemichiganminnesotamissourimontananebraskanevadanew-yorknorth-dakotaohiooregontexasutahwashingtonwisconsinwyoming

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