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

Black-crowned Night Heron Population Trend in South Dakota

All statesWetland birds

Black-crowned Night Heron in South Dakota has collapsed: down 87% on the route-weighted index since 1969.

-87%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 →
20Routes 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 →
56YearsYears 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-crowned Night Heron 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-crowned Night Heron has collapsed in South Dakota: down 87% on the route-weighted index since 1969.

Black-crowned Night Heron Population Forecast in South Dakota

If the recent trend holds, Black-crowned Night Heron in South Dakota is projected to fall about 100% by 2028 — from 0.07 in 2023 to a central estimate of 0.00 (95% range 0.00–1.1). A 5-year backtest shows a typical error of ±136.2%, with 100% of held-out values landing inside the 95% band.

-100%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 →
0.00Projected 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 →
0.00–1.195% 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 →
±136.2%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-crowned Night Heron in South Dakota is projected to fall about 100% by 2028 — from 0.07 in 2023 to a central estimate of 0.00 (95% range 0.00–1.1). A 5-year backtest shows a typical error of ±136.2%, with 100% 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 →
20240.010.001.1
20250.000.001.1
20260.000.001.1
20270.000.001.1
20280.000.001.1

Black-crowned Night Heron Survey Routes in South Dakota

Routes recording Black-crowned Night Heron 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 →
Tripp2119991999
Britton520211973
White Lake420111967
Veblen420081980
Howard320041970
Crow Creek320221972
Wilmot319971967
Volga220131968
Forbes220231967
Long Lake220171967
Chamberlain119721968
Raymond120211968
Roswell119971969
Broadland120132001
Ft Thompson119981969
Conde119681968
Gettysburg120191972
Ottumwa119671967
Lacreek120141991
Lane 2120132012

Black-crowned Night Heron Population Trend in Other States

alabamaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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