BirdAnalyst
Species · Colorado · BBS 2026 Release · 1966–2025

Wilson's Phalarope Population Trend in Colorado

All statesShorebirds

Wilson's Phalarope in Colorado has collapsed: down 76% on the route-weighted index since 1973.

-76%Since 1973TrendPercent 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 →
43Routes 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 →
50YearsYears 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 ColoradoNotable 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 collapsed in Colorado: down 76% on the route-weighted index since 1973.

Wilson's Phalarope Population Forecast in Colorado

If the recent trend holds, Wilson's Phalarope in Colorado is projected to rise about 41% by 2030 — from 0.15 in 2025 to a central estimate of 0.21 (95% range 0.00–1.1). A 5-year backtest shows a typical error of ±406.4%, with 100% of held-out values landing inside the 95% band.

+41%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 →
0.21Projected 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 →
0.00–1.195% 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 →
±406.4%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, Wilson's Phalarope in Colorado is projected to rise about 41% by 2030 — from 0.15 in 2025 to a central estimate of 0.21 (95% range 0.00–1.1). A 5-year backtest shows a typical error of ±406.4%, with 100% of held-out values landing inside the 95% band.19682030
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 →
20260.230.001.1
20270.230.001.1
20280.220.001.1
20290.210.001.1
20300.210.001.1

Wilson's Phalarope Survey Routes in Colorado

Routes recording Wilson's Phalarope in Colorado.
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 →
Nunn2920142010
Briggsdale1019961989
Alamosa920251988
Julesburg820212004
Lay720251996
Pritchett720022002
Parlin419891968
Karval420172001
Amherst419951995
Stillwater Pass420032001
Buford320091985
Kiowa320002000
Doyleville320051988
Edler320142014
Lamar220232021
Rio Grnds Rs219921992
Bennett220012001
Powderhorn219951995
Stoneham220211998
Cortez219971988
Maybell120181974
Fleming120151987
Last Chance119831983
Colona119881988
Moffat120211970

Wilson's Phalarope Population Trend in Other States

californiaidahoillinoisiowakansasminnesotamontananebraskanevadanew-mexiconorth-dakotaoklahomaoregonsouth-dakotatexasutahwashingtonwisconsinwyoming

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