“Good weather for ducks.” How often have you heard a drizzly spring day described this way? But how about if the weather is 15 degrees Fahrenheit, with a stiff wind and light snow? Could that be good weather for ducks?
It is certainly good enough weather for the common merganser.
The common merganser is a duck that is roughly the size of a mallard, perhaps a little bigger. Compared to the other merganser species in our area, it is rather plain. The males have iridescent, greenish-black heads. Unlike the extravagantly crested hooded merganser and the tousle-topped, red-breasted merganser, males don’t have a crest – a tuft of long feathers – on their heads.
Its neck and breast are white. Its sides and tails are gray.
The female has a brownish red head and a crest. To me the crest looks exactly like a spiky, auburn hairdo. The female’s body has more gray. Both sexes’ wings are black on top, and both have a long, thin, red bill.
Common mergansers are found throughout arctic and sub-arctic areas. In addition to a North American subspecies, there are also European and Asian subspecies. In Great Britain, this bird is called a goosander. It winters in England and is found all year in Scotland.
Our mergansers spend the winter in northern New England and points south from coast to coast across the United States. In Vermont and New Hampshire, the common merganser is counted both in the Breeding Bird Survey (summer) and the Christmas Bird Count.
While you can find common mergansers in our area all year round, according to the records in eBird (a project developed by the Cornell Lab of Ornithology and the National Audubon Society that tracks bird sightings), the greatest percentage of observers see common mergansers in January, but the greatest number of common mergansers are seen in the beginning of April.
In most of the United States, common mergansers are a bird of winter, arriving after the leaves fall and disappearing again before the crocuses bloom.
Common mergansers like to spend their winters on lakes. There are many winter eBird sightings of common mergansers on Lake Champlain. There are also many sightings of mergansers on the Connecticut River.
There are not as many eBird sightings of the common merganser in New Hampshire. Ed Robinson, waterfowl biologist for New Hampshire Fish and Game, says that while the state doesn’t survey specifically for common mergansers, they are seen throughout the state on the larger lakes and rivers.
When the lakes freeze, the common mergansers head to more swiftly flowing, and not-yet-frozen rivers and streams.
There, they gather in same-sex groups of 10 to 20, face upstream, and dive for fish. Because of their diet, common mergansers are sometimes called “fish ducks.” Their serrated red bills, which are used to grasp those slippery fish, make them one of several ducks called “sawbills.”
The number of common mergansers was in serious decline 30 to 40 years ago. Bill Crenshaw, waterfowl biologist with Vermont Fish and Wildlife, suspects that this duck’s fish diet holds the key to both its decline and its comeback.
“Fish-eating birds really took it on the chin because of DDT,” he says. Common merganser numbers have followed roughly the same trends as populations of bald eagles and osprey, two other fish-eating birds. All have recovered from serious declines now that DDT has been banned and other efforts have been made to improve their prospects.
The common merganser’s fish diet also means there is almost no hunting pressure on its numbers. Most duck hunters pass up common mergansers because their fish diet causes them to taste, Crenshaw says generously, “a little tangy.”
Common merganser couples pair up during the winter and early spring. Starting in April, they head to their breeding sites, which are located all across Canada, here in northern New England, and in the mountains of the West.
Common mergansers prefer a tree cavity for their nest, but they are not too fussy, Crenshaw reports. They will settle for a stump or a nest box designed for wood ducks or goldeneye ducks.
They lay 9 to 12 eggs, and the ducklings are quite precocious. They leave their nest hole about a day after hatching, sometimes dropping from heights of 15 feet to the ground or the water below.
The mama common merganser watches after her brood, but she does not feed them. The ducklings feed themselves on aquatic insects, such as backswimmers, dragonflies, and caddis flies, at first. At about 12 days old, they start eating fish.
And from then on, wherever they can dive for fish, they can live. It doesn’t matter if it snows or sleets. As long as there is open water and fish below, it’s good weather for the common merganser.