Red-breasted Merganser
Red-breasted Merganser has surged: up 84% on the route-weighted index since 1969.
About the Red-breasted Merganser
The Red-breasted Merganser (Mergus serrator) 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 64 Breeding Bird Survey routes across 5 states, most concentrated in the BCR 2.
- Family
- Anatidae · Waterfowl
Notable Red-breasted Merganser Trends
No notable trend signals for Red-breasted Merganser. See the full index history below.
Red-breasted Merganser Population Forecast
If the recent trend holds, Red-breasted Merganser is projected to stay roughly flat through 2029, near 0.04 (95% range 0.01–0.08). A 5-year backtest shows a typical error of ±139.8%, with 100% of held-out values landing inside the 95% band.
| Year | Projected index | 95% low | 95% high |
|---|---|---|---|
| 2025 | 0.04 | 0.01 | 0.08 |
| 2026 | 0.04 | 0.01 | 0.08 |
| 2027 | 0.04 | 0.01 | 0.08 |
| 2028 | 0.04 | 0.01 | 0.08 |
| 2029 | 0.04 | 0.01 | 0.08 |
Where the Red-breasted Merganser Is Detected
BBS routes recording Red-breasted Merganser, sized by most recent count.
Red-breasted Merganser Population Trend by State
| Alaska | -42% | 1985 | 47 |
| Maine | insufficient data | n/a | 2 |
| Michigan | insufficient data | n/a | 6 |
| Minnesota | -27% | 1976 | 5 |
| Wisconsin | -90% | 1969 | 4 |
Red-breasted Merganser Population Trend by Region
Bird Conservation Regions are the ecological unit for trends.
| BCR 2 | -69% | 1985 | 18 |
| BCR 4 | +382% | 1991 | 16 |
| Northern Pacific Rainforest | -53% | 1991 | 9 |
| Boreal Hardwood Transition | -87% | 1969 | 13 |
Red-breasted Merganser Conservation Status
Our route-weighted index shows it up about 84% since 1969.
Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22. Trend is a route-weighted relative-abundance index, not an absolute population.