The Mergansers

By Al Lowe
Contributor

Mergansers are often sneeringly referred to as “fish ducks.” This name is appropriate, as a good portion of their diet is made up of fish and they are very well adapted to catching fish. I am told that a merganser, when cooked, tastes awful – sort of a mixture of very old fish and rancid butter.
The are three species of merganser in Canada, and we have them all here in Northern Ontario. They are the Common Merganser (Mergus merganser), Red Breasted Merganser (Mergus serrator) and the Hooded Merganser (Lophodytes cucullatus). All three of these species are fairly similar. This is especially true of the females, which are very close to being look-alikes. The female Hooded has a darker head and larger crest than the others. The differences between the other two are quite small. If you are a dedicated birder, you can distinguish them, providing you are also really alert. If you are casual about it, forget the whole thing.
The male birds are a little easier. First, the Hooded in his spring plumage, has a very prominent black and white crest, which is unmistakable, but in a shaggy sort of way. Its upper parts and wings are fairly dark. The Common Drake also has a green head with hardly any crest, and it has a lot of white on its back, sides and wings. So you can tell the drakes apart quite easily in the spring. In the fall, when all the ducks are in the eclipse plumage, all three are mottled brown and are somewhat scruffy looking.
Mergansers all have beaks which are designed for catching and holding fish. The end of the beak is hooked and the sides are heavily toothed. These birds are good divers and can swim well under water. Their diet is not entirely fish, as they also eat insects, crayfish and so on, as well as some vegetable matter. In Scotland, as well as in parts of the Maritimes they are disliked because of a supposed fondness for young Salmon. In fact, mergansers feed on much slower, easier to catch fish such as suckers and so on.
Two of these species nest mainly in hollow trees, the Hooded and the Common. The other prefers locations under stumps or hollow logs. They lay about a dozen eggs on the average. Merganser families are rather odd in the way in which they handle their ducklings. Any female will freely adopt any other female’s young. So you may see one duck with only three or four young ones and then another with 25 or so. You may also see a duck with one group of ducklings which are obviously quite different in age from the others.
Our three mergansers could not in any sense of the word be considered game birds, but they are an integral part of the ecology of this part of Ontario. Leave them to themselves – they do not do any harm and they are intriguing to watch.