Species · Colorado · BBS 2025 Release · 1966–2024
Lesser Scaup Population Trend in Colorado
Lesser Scaup in Colorado has surged: up 568% on the route-weighted index since 1989.
+568%Since 1989
18Routes In State
37Years
Notable Lesser Scaup Trends in Colorado
long arc increasecomputed index
Lesser Scaup has surged in Colorado: up 568% on the route-weighted index since 1989.
Lesser Scaup Population Forecast in Colorado
If the recent trend holds, Lesser Scaup in Colorado is projected to fall about 29% by 2029 — from 0.83 in 2024 to a central estimate of 0.60 (95% range 0.17–1.0). A 5-year backtest shows a typical error of ±37%, with 80% of held-out values landing inside the 95% band.
-29%Change by 2029
0.60Projected 2029 index
0.17–1.095% range
±37%Backtest error
| Year | Projected index | 95% low | 95% high |
|---|---|---|---|
| 2025 | 0.57 | 0.15 | 0.99 |
| 2026 | 0.58 | 0.15 | 1.0 |
| 2027 | 0.58 | 0.16 | 1.0 |
| 2028 | 0.59 | 0.17 | 1.0 |
| 2029 | 0.60 | 0.17 | 1.0 |
Lesser Scaup Survey Routes in Colorado
| Rio Grnds Rs | 78 | 2024 | 1991 |
| Mcphee Res. | 12 | 2012 | 2005 |
| Dinosaur | 10 | 2012 | 1995 |
| Nunn | 5 | 2019 | 2019 |
| Tincup | 3 | 2024 | 1994 |
| Willow Peak | 3 | 2018 | 1988 |
| Walden | 2 | 2016 | 1990 |
| Dunckley Pas | 2 | 2017 | 2006 |
| Colona | 2 | 2014 | 2014 |
| Piedra | 2 | 2023 | 2023 |
| Yellowjacket Pass | 1 | 2022 | 2011 |
| Lost Lake | 1 | 2002 | 2002 |
| Stillwater Pass | 1 | 1999 | 1999 |
| Tarryall | 1 | 1989 | 1989 |
| Kiowa | 1 | 1980 | 1980 |
| Doyleville | 1 | 2012 | 1989 |
| Ragged Mtn. | 1 | 2006 | 2006 |
| Groundhog Rs | 1 | 1995 | 1994 |
Lesser Scaup Population Trend in Other States
Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22.