The common merganser nests in trees located in forests near lakes and streams. While some may migrate when local freshwater freezes, others will remain here year round. Primarily the common merganser eats fish and other aquatic game.
A common merganser is shown in the last photo below preparing to swim through a culvert protection structure. This unique structure has been very successful in preventing beavers from blocking a culvert with wood, while letting salmon, birds, beavers, and other animals to swim through.