Lesser Scaup
Lesser Scaup has surged: up 823% on the route-weighted index since 1968.
About the Lesser Scaup
The Lesser Scaup (Aythya affinis) is a North American member of the Ducks, Geese & Waterfowl (Anatidae). In this analysis it is grouped with the waterfowl.
- Size
- 12–43.5 in long (30–110 cm) — a medium to large waterfowl (typical for the family)
- Habitat
- Lakes, ponds, rivers, marshes and sheltered coastal waters.
- Diet
- Aquatic plants, seeds and invertebrates, dabbled at the surface or dived for.
- Range
- Recorded on 321 Breeding Bird Survey routes across 19 states, most concentrated in the Prairie Potholes.
- Family
- Anatidae · Waterfowl
Notable Lesser Scaup Trends
No notable trend signals for Lesser Scaup. See the full index history below.
Lesser Scaup Population Forecast
If the recent trend holds, Lesser Scaup is projected to rise about 88% by 2029 — from 0.14 in 2024 to a central estimate of 0.27 (95% range 0.11–0.43). A 5-year backtest shows a typical error of ±98.5%, with 40% of held-out values landing inside the 95% band.
| Year | Projected index | 95% low | 95% high |
|---|---|---|---|
| 2025 | 0.26 | 0.09 | 0.42 |
| 2026 | 0.26 | 0.10 | 0.43 |
| 2027 | 0.27 | 0.10 | 0.43 |
| 2028 | 0.27 | 0.10 | 0.43 |
| 2029 | 0.27 | 0.11 | 0.43 |
Where the Lesser Scaup Is Detected
BBS routes recording Lesser Scaup, sized by most recent count.
Lesser Scaup Population Trend by State
| Alaska | +153% | 1985 | 41 |
| California | +24% | 1974 | 9 |
| Colorado | +568% | 1989 | 18 |
| Idaho | +43% | 1973 | 21 |
| Iowa | insufficient data | n/a | 2 |
| Kansas | insufficient data | n/a | 1 |
| Michigan | insufficient data | n/a | 1 |
| Minnesota | -85% | 1973 | 13 |
| Montana | -24% | 1975 | 50 |
| Nebraska | insufficient data | n/a | 3 |
| Nevada | -33% | 1991 | 8 |
| New Mexico | insufficient data | n/a | 3 |
| North Dakota | +927% | 1970 | 36 |
| Oregon | +170% | 1971 | 20 |
| South Dakota | -21% | 1969 | 23 |
| Utah | -47% | 1988 | 13 |
| Washington | -60% | 1981 | 15 |
| Wisconsin | insufficient data | n/a | 6 |
| Wyoming | +121% | 1977 | 38 |
Lesser Scaup Population Trend by Region
Bird Conservation Regions are the ecological unit for trends.
| BCR 4 | -44% | 1986 | 28 |
| Great Basin | +183% | 1971 | 61 |
| Northern Rockies | +82% | 1977 | 58 |
| Prairie Potholes | +476% | 1969 | 69 |
| Southern Rockies / Colorado Plateau | +369% | 1982 | 29 |
| Badlands and Prairies | +23% | 1971 | 37 |
| Prairie Hardwood Transition | -76% | 1968 | 8 |
Lesser Scaup Conservation Status
Our route-weighted index shows it up about 823% since 1968.
Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22. Trend is a route-weighted relative-abundance index, not an absolute population.