Duck of the Week --- Common Merganser

Common Merganser (Mergus merganser) - (25" in length, 34 " wingspan, 3.4 lbs. - males average larger) Locally common on deep, clear lakes and rivers. Forms small groups in winter that may gather to large numbers at prime sites. The male is long and slender, mostly white (showing white wing patches in flight) with an iridescent green head. The female has a darker brown head with a sharply contrasting white chin and neck. The female gives harsh call notes, while the male in display has a faint 'twanging' quality.

The potential life span of a Common Merganser is 13 years. It is a very common species in Ontario. Common Mergansers are short-distance migrants or residents on open water where available in winter.

Common Merganser male and female (with male call) - For a Range Map click here.

The Common Merganser is a freshwater diving duck, feeding mostly on fish but will also take insects, mollusks, crustaceans, worms, frogs, small mammals, birds and plants. This species is referred to as the 'Sawbill' due to its long, serrated bill which helps hold slippery fish prey. Gulls wait for Mergansers to surface and try to steal their meals, sometimes a Bald Eagle may do the same. Common Mergansers reside on lakes, ponds, rivers, streams and islands.

Common Mergansers nest in tree cavities by freshwater lakes or rivers in wooded areas. Infrequently they may nest in holes in the bank and will use nest boxes. Strange places Merganser nests have been found include: rock crevices, hollow logs, old buildings or even in chimneys. In tree cavities, nothing is added save for down. The nest cavity is normally in old holes excavated by large woodpeckers or where a larger limb has broken off. The Common Merganser prefers a cavity situated 15-50 feet up a tree. When nesting on the ground, the nest is a hollow lined with nearby plants with a 12 inch outside diameter, 7.5 inches inside, at a depth of 4 inches.

The Common Merganser's clutch size numbers between 8 and 12 eggs. Nestlings are prococial and downy and are tended to by the female alone. The young remain in the nest 1-2 days before leaving with the female. The mother protects the young but does not feed them. Fledging young dive to catch their own food which is at first mainly aquatic insects, but turns over to fish at 12 days. They are independent in 5 weeks time.

Look for the Common Merganser and many other species of waterfowl at the Hullett P.W.A. Look for a new Duck of the Week each week. Also see our Marsh Bird of the Month feature.