- 21.3–28 in
- 33.9 in
- 31.7–76.2 oz
- Grand Harle, Mergo mayor (French)
- The Common Merganser usually nests in tree cavities, either those made by large woodpeckers or from where a limb broke off. It will also use a nest box. Infrequently a Common Merganser might make its nest in a rock crevice, a hole in the ground, a hollow log, in an old building, or in a chimney.
- Young Common Mergansers leave their nest hole within a day or so of hatching. The mother protects the chicks, but she does not feed them. They dive to catch all of their own food. They eat mostly aquatic insects at first, but switch over to fish when they are about 12 days old.
- Gulls of various species often follow flocks of foraging Common Mergansers. The gulls wait for the ducks to come to the surface with fish, and then they try to steal their prey. Occasionally even a Bald Eagle will try to steal a fish from a successful merganser.
Breeds along lakes and rivers bordered by forests. Winters on large lakes, rivers, coastal bays, and estuaries.
Small fish, insects, mollusks, crustaceans, worms, frogs, small mammals, birds, and plants.
- Clutch Size
- 6–17 eggs
- Egg Description
- Creamy white
- Condition at Hatching
- Covered with down, eyes open. Leave nest within one or two days after hatching.
Nest in tree cavity or nest box, lined with downy feathers from chest of female.
Dives underwater to catch prey.
Populations appear stable.
- Mallory, M. and K. Metz. 1999. Common Merganser (Mergus merganser). In The Birds of North America, No. 442 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.