Each April, as the ice finally starts to melt in our bay on Sylvan Lake, I watch for the early arriving ducks that frequent the narrow strip of water that opens up between the shoreline and the remaining ice pack. Joining the Common Goldeneyes, which are usually the first to appear, are the larger and more majestic Common Mergansers.
During migration and outside of the breeding season, these highly social ducks swim and feed together in groups. It is always a delight to be sitting in my blind, watching them dive, groom and squabble. I have also had the opportunity to photograph them resting and grooming while perched atop shoreline rocks.
These long-bodied ducks are easily identified by their distinctive straight, narrow red bills and distinctive colouration: males have stark white bodies and iridescent-green heads while the females are grayish in colour with rusty red heads topped by a distinctively shaggy crest . Juveniles resemble adult females.
Common Mergansers, like their cousins the Hooded and Red-breasted Mergansers, specialize in eating fish. They can dive to great depths and their thin, serrated-edged beaks enable them to grasp even the slimiest of prey. This fish diet is supplemented during the breeding season with aquatic invertebrates and other small quarry.
Interestingly, Common Mergansers—like the other two merganser species as well as goldeneyes, Buffleheads and Wood Ducks—are cavity nesters. The female chooses her nest site in a natural cavity, rock crevice or old woodpecker hole that is located within a kilometre or so from water. The nest sites can be up to 30 m off the ground. I have never been lucky enough to find a Common Merganser using an artificial cavity, although there are records of them taking up residence in nestboxes.
Once pair-bonded, the male remains near the nesting site until the female begins to incubate, at which point he abandons her to join other males in flocks.
Like other cavity-nesting ducks, the young are incubated for about a month, then brooded for a day or two after hatching. They then jump from the cavity to join their mother on a perilous trek to water. Once in the water, the young chicks often ride on their mother’s backs (an observation I have yet to witness). Broods sometimes join together, resulting in groups of multiple females with 40 or more young. They remain with her for most of the summer. I look forward to more merganser watching this spring and summer!
Myrna Pearman is the Resident Naturalist at Chin Ridge Seeds. She is a retired biologist, nature writer, photographer and author of several books. Her books are available at www.myrnapearman.com. She can be reached at myrna@myrnapearman.com.
