Common Merganser Population Analysis
Common Merganser has surged: up 14× on the route-weighted index since 1968.
About the Common Merganser
The Common Merganser (Mergus merganser) 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 751 Breeding Bird Survey routes across 29 states, most concentrated in the Northern Rockies.
- Family
- Anatidae · Waterfowl
Notable Common Merganser TrendsNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →
No notable trend signals for Common Merganser. See the full index history below.
Common Merganser Population Forecast
If the recent trend holds, Common Merganser is projected to rise about 111% by 2030 — from 0.07 in 2025 to a central estimate of 0.16 (95% range 0.08–0.23). A 5-year backtest shows a typical error of ±86.2%, with 20% of held-out values landing inside the 95% band.
Where the Common Merganser Is Detected
BBS routes recording Common Merganser, sized by most recent count.
Common Merganser Population Trend by State
Common Merganser Population Trend by Region
Bird Conservation Regions are the ecological unit for trends.
Common Merganser Conservation Status
Our route-weighted index shows it up about 1270% since 1968.
Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14. Trend is a route-weighted relative-abundance index, not an absolute population.