Courtesy Kenn Kaufman
Hooded Mergansers are found in the forested areas of eastern North America, with the densest concentrations around the Great Lakes. Another population breeds in the forested Pacific Northwest. In between, they occur mainly as migrants, if at all. This merganser is the only member of its genus to occur exclusively in North America.
A legend for the range map to the right can be found here.
This secretive duck prefers quiet, out-of-the-way wooded ponds, lakes, streams, and swamps. In migration, they prefer similar habitat, but make use of a wider variety of areas with open fresh water. The presence of mature, cavity-bearing trees is essential for nesting, although Hooded Mergansers occasionally make use of nest boxes placed in less typical habitat. These mergansers are known for choosing hidden wet areas, where they can be extremely difficult to detect, even by experienced bird watchers and researchers.
Like other mergansers, Hooded Mergansers dive for their food. They are strong underwater swimmers, with eyes specially adapted for foraging amidst the murky bottoms of lakes and ponds. Unlike other mergansers, which prefer fish, a large portion of the Hooded Merganser’s diet is made up of insects and crustaceans, particularly crayfish. Small fish and a limited amount of vegetation are also eaten.
Pairs form over the fall and winter. In spring, the female merganser chooses a suitable nest cavity, where she lays her clutch of eggs. The nest cavity is near water, and typically 10 to 50 feet above the ground. Once the cavity is chosen, available materials may be moved around a bit, but only downy feathers are added. Males disappear shortly after the nest site is chosen; females are responsible for incubating and rearing the young. When her ducklings are only a day old, the female flies to the ground and calls to them until they climb out, one by one, and leap to the ground. At this point she leads them to water, where they are immediately able to feed themselves, swim, and even dive. A curious aspect of breeding among Hooded Mergansers is nest parasitism, or the laying of eggs in other birds’ nests. Hooded Mergansers are both the perpetrators and victims of this practice; in extreme cases, females have been found attempting to incubate as many as 40 eggs, a fraction of which are actually her own.
Depending on where they breed, most populations of Hooded Mergansers are short- to medium- distance migrants. This hardy species often winters as far north as open fresh water can be found. In spring, they may arrive on breeding grounds within days of the local ice melt.