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

Wilson's Phalarope Population Trend in South Dakota

All statesShorebirds

Wilson's Phalarope in South Dakota has fallen sharply: down 57% on the route-weighted index since 1969.

-57%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 →
46Routes 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 Wilson's Phalarope 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 →

Wilson's Phalarope has fallen sharply in South Dakota: down 57% on the route-weighted index since 1969.

Wilson's Phalarope Population Forecast in South Dakota

If the recent trend holds, Wilson's Phalarope in South Dakota is projected to fall about 20% by 2030 — from 0.54 in 2025 to a central estimate of 0.43 (95% range 0.00–1.3). A 5-year backtest shows a typical error of ±78.9%, with 100% of held-out values landing inside the 95% band.

-20%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 →
0.43Projected 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 →
0.00–1.395% 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 →
±78.9%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, Wilson's Phalarope in South Dakota is projected to fall about 20% by 2030 — from 0.54 in 2025 to a central estimate of 0.43 (95% range 0.00–1.3). A 5-year backtest shows a typical error of ±78.9%, 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 →
20260.460.001.3
20270.450.001.3
20280.440.001.3
20290.440.001.3
20300.430.001.3

Wilson's Phalarope Survey Routes in South Dakota

Routes recording Wilson's Phalarope 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 Lake3020111967
Maurine1020191969
Chamberlain820111968
Howard620122012
Lacreek620191991
Roswell520061969
Ft Thompson519681968
Rosebud419681968
Pioneer420021993
Gorman420101995
Reva420251987
Lodgepole420251995
Railroad Butte419981998
Tripp320251986
Conde319841967
Long Lake320171967
Promise319731973
Ottumwa319981967
Harding320251968
Marcus320102001
Raymond220111967
Broadland220132001
Veblen220231972
Britton220231971
Ardmore220191977

Wilson's Phalarope Population Trend in Other States

californiacoloradoidahoillinoisiowakansasminnesotamontananebraskanevadanew-mexiconorth-dakotaoklahomaoregontexasutahwashingtonwisconsinwyoming

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