Above: Male and female Common Mergansers rest on a gravel beach at Grand Rapids; photo by Peter Taylor
How do I recognize it?
Many diving ducks look black-and-white at a distance, but a breeding male Common Merganser has more white plumage than most. The dark head has a deep green lustre, less brilliant than a Mallard, and the slender bill is red. Females and juveniles have extensive grey tones, a ragged crest, and somewhat duller leg and bill colours than the male. Care is needed to distinguish this species from the Red-breasted Merganser.
Above: A male Common Merganser leaves a wake on glassy water near Otter Falls; photo by Peter Taylor
Does it migrate?
Common Mergansers are among the first spring arrivals and the last fall departures in the Manitoba migration calendar. Relatively short-distance migrants, they overwinter mainly in the northern half of the U.S.A. and milder parts of Canada. They breed in much of Canada and adjacent parts of the U.S.A. A different subspecies occurs widely in northern Eurasia.
Above: This mother Common Merganser (far left) hustled her young to safety onshore when an otter swam nearby; photo by Peter Taylor
Where does it live?
Common Mergansers subsist on fish and nest primarily in large tree-cavities near boreal lakes and rivers. Spring migrants turn up at open water on major rivers as the ice starts to break up. Flocks of moulting males gather on the Hudson Bay coast in summer.
Above: Water beads up on this Common Merganser’s plumage as she fishes in the Waterhen River; photo by Peter Taylor
Where can I see it?
Common Mergansers are most easily found on large lakes and rivers during migration (late March to early May, and October-November). Good places to find them include Whiteshell Provincial Park and Lake Winnipeg. In summer, look for family groups at lakeside cottage areas – they sometimes even nest in spaces under cottages.
Above: Like other diving ducks, mergansers patter along the water surface to reach take-off speed; photo by Peter Taylor
While the Common Merganser is both widespread and numerous, there is evidence of some decline, possibly linked to contamination of aquatic food chains, and better monitoring of this species’ numbers is needed.
Above: A mother Common Merganser tells off a Herring Gull while her young ones doze; photo by Peter Taylor
Did you know:
Mergansers are sometimes called “sawbills” because of their serrated bills that help to grasp fish. In Britain, the Common Merganser is called Goosander.
Written by Peter Taylor