- 20.1–25.2 in
- 26–29.1 in
- 28.2–47.6 oz
- Harle huppé (French)
- Mergo copetón (Spanish)
- The Red-breasted Merganser breeds farther north and winters farther south than the other American mergansers.
- The oldest recorded Red-breasted Merganser was a female, and at least 9 years, 6 months old when she was shot in Alaska, the same state where she had been banded.
Mostly fish; also crustaceans, insects, and tadpoles.
- Egg Description
- Condition at Hatching
- Covered with down, eyes open. Leave nest within one or two days after hatching.
Depression in ground, lined with down. Often placed under boulder or in dense shrubs.
Dives underwater to catch prey.
There is little significant information on Red-breasted Merganser population trends and numbers. Populations appear to have declined between 1966 and 2014, according to the North American Breeding Bird Survey. A 2015 study by the U.S. Fish and Wildlife Service estimated the population of all three merganser species together to be around 400,000. Red-breasted Merganser is not on the 2014 State of the Birds Watch List. These birds may be susceptible to pesticides, toxic metals, and acid rain that degrade their habit, reduce prey and thin eggshells. Though they are not prized as a game bird, some Red-breasted Mergansers are shot every year either for sport or by mistake (The U.S. Fish and Wildlife Service estimates some 35,000 Common and Red-breasted Mergansers are shot by hunters annually). At times they have been targeted for eradication because they were thought to threaten salmon and trout stocks.
- Titman, R. D. 1999. Red-breasted Merganser (Mergus serrator). In The Birds of North America, No. 443 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.
- North American Bird Conservation Initiative, U.S. Committee. 2014. State of the Birds 2014 Report. U.S. Department of Interior, Washington, DC.
- U.S. Fish and Wildlife Service. 2015. Waterfowl Population Status, 2015. U.S. Department of the Interior, Washington, DC.
- USGS Patuxent Wildlife Research Center. 2015. Longevity records of North American Birds.
- USGS Patuxent Wildlife Research Center. 2014. North American Breeding Bird Survey 1966–2014 Analysis.