It's not exactly flattering to be called "common." In the millennia-long history of England and its empire, if you were not royalty, you were considered "a commoner," and occupied a lower rung on the social ladder. In its government, if you were not royalty you had to be elected by your peers to be a member of-you guessed it-the House of Commons.

"Common" can also identify some of the widely used things in our lives. Ask a hardware store employee to help you find some nails for a project, and he might ask if you want galvanized, hardened, ring-shanked or "common nails"-which are basic, ordinary and inexpensive.

"Common" has also found its way into the identities of creatures in the world around us. This time of year, when the ice has so recently lost its grip on our lakes, the last lingering snowbanks have melted and the first leaves have broken free of their buds, we're visited by countless migratory birds returning from wintering grounds to the south. Some will stay with us and attempt to raise families here; others are just passing through on their way to breeding destinations to the north.

A few of these migrants have been condemned by the scientific community to bear "common" in their official names. They have no advocate to protest this undeserved slight, and to make the case that simply being abundant-or being found over a broad area of the country-is no reason to saddle them with an uncomplimentary name like "common."

A case in point is the loon; the "common loon," if we hew to the official name of Minnesota's state bird, a symbol of wilderness but also a fixture on many, many lakes from our state's mid-latitudes all the way to the Canadian border. The lake where the family cabin is perched high on a south-facing hill is a good example.

Except in the most inclement weather, it's unlikely a day will go by between ice-out and freeze-up without a loon's high, piercingly-loud, manic laughter being heard. Why is it that-unlike most birds, including others in the waterfowl clan-that the loon's ancestors evolved a call that can echo across an entire lake? Is it an advantage in finding a mate during courtship? Or a means to establish territorial boundaries? Does the habitat niche that loons occupy-including some incredibly large lakes-make a loud voice a necessity?

Loons enjoy the goodwill of anglers, even though they are amazingly successful catchers of fish. If loons were as abundant as the cormorants that nest in densely-populated colonies on some northern lakes-and consume many fish, including precious young walleyes-it might be a different story. Having a loon pop up unexpectedly from the depths within casting distance of your boat is a welcome occasion, contrary as that might seem.

Loons are among the fastest and most agile of the waterfowl that dive underwater to feed. They can also reach amazing depths, particularly when you realize they must surface to breathe. Loons have been caught-and drowned-in commercial fishermen's nets set at depths as great as 90 to 100 feet, tops for any bird species found in North America.

Unlike most birds whose bones are hollow to make them more airworthy, loons' bones are solid, which aids their descent underwater to feed. A loon can compress its feathers against its body to expel trapped air, making it less buoyant and more streamlined for more efficient swimming, aided by legs placed in the perfect position for propulsion-closer to the rear of its body than other waterfowl. Loons also slow their heart rate in order to conserve oxygen during their exceptionally deep dives. So much for the "common" in common loon.

Shortly after ice-out this spring came the arrival of a squadron of common mergansers; large ducks, generally slightly bigger than a mallard. Most duck hunters think of them as "mistake" ducks, because their diet-like that of the loon-is largely fish; sometimes surprisingly large fish. This makes their flesh stronger tasting than ducks that feed on grasses, tubers, wild rice or grain, and-most feel-much less palatable on the table. Others have devised recipes with marinades, spices and the like that can bring out the best-or disguise the worst-in a duck like the merganser.

Whereas a loon has a thick, sharp pointed bill resembling a dagger, mergansers have a narrow bill lined from end to end with tiny tooth-like ridges for grasping fish securely. If you've ever seen or used an electrical "alligator" clip used to clamp a wire to a battery post or the terminals of an electrical device, you've seen a good visual approximation of a merganser's bill.

Though almost certainly coincidence, drake common mergansers-like loons of both sexes-wear plumage that is mostly a striking black and white. Drakes have an iridescent green head that in the right light can be mistaken for black. The effect reminds one of special occasion formal wear. Like most duck species, the female is less showily plumed, mostly in tones of grey and brown.

One of the characteristics that helps identify common mergansers in flight is their habit of flying "on the deck" very close to the water, at least compared to many duck species. Their wings are relatively long compared to some diving ducks, with wingbeats that are deliberate and less rapid than ducks with more stubby wings. The common merganser's profile may resemble a loon in flight, with body, neck and head in straighter alignment than ducks that carry their head more erect in flight. Profile, wingbeat and flight habit are important identification clues in the poor light so often encountered in duck hunting.

Common mergansers spend the cold months in large flocks, feeding and courting prior to the push northward to nest. This aligns with the large number that spent time with us during the last days of our lake's ice, and the immediate post ice-out period. Then they were gone, though it wouldn't be a total surprise if one of these tree cavity nesting ducks found the area to its liking and stayed on to raise a family. Generally, though, common loons breed farther north, in the upper reaches of Minnesota and in Canada.

Not a hunter's favorite, perhaps; but uncommonly beautiful, and uncommonly interesting. So much for a name!