The Common Merganser is an elegant looking bird. The “common” refers to its being the most abundant of the mergansers. They have slender red bills, which are serrated to grasp slippery fish; hence the name “saw-bill”. Other names for the Common Merganser are Sheldrake and in Europe, Goosanders.
They sit low in the water and dive as deep as thirty feet to fish. At twenty-two to twenty-seven inches the Common Merganser is also the largest of the mergansers. Unlike Red-breasted Mergansers that prefer the shallow salt water of our coast, the Common Merganser prefers the fresh water of our forested rivers and deep ponds and lakes.
The females and non-breeding males have a reddish-brown head and crest, a distinctive white throat and a grey body. The breeding males have a gorgeous, glossy green head, bloodred bill, black back and white breast. They fly flat, like an arrow, low to the water, showing white wing bars.
Common Mergansers are seen in large flocks for most of the year. They break into breeding pairs in early spring. Their favorite nesting spot is a hole in a tree. The male leaves once the nine to twelve green-colored eggs are laid. The female incubates the eggs for thirty-five days. The young jump from the nest when they are a couple of days old but they cannot fly for the first two months. Mothers protect their young but do not feed them. They eat aquatic insects for the first two weeks and then switch to small fish.
Adult Common Mergansers catch small trout, carp, perch and suckers. While some think that mergansers have a negative effect on salmonids, others think that by eating the small fish they are helping the larger fish by making more food available.