Has a hunter in your family ever shot a bluebill? That's one of the folk names used for two species of ducks known officially as scaup, greater scaup and lesser scaup.

The greater scaup is larger, as you would suspect, about an inch longer in body, a few ounces heavier. To the scientific world, the greater scaup is known as Aythya marila, the lesser scaup as Aythya affinis.

These birds, like most others, have two names, common and scientific. The scientific name has two parts, the first for its group, the second its individual designation.

The name bluebill has an obvious origin — the bill of the bird is bluish in color. Scaup is an Old English word once used to describe beds of shellfish, a favored food of this duck. Aythya is Greek for a kind of waterbird. (You can find the word in Homer's Odyssey.) Marila is thought to come from the Greek word for charcoal (this duck's back is dark). Affinis means "related to."

The black-capped chickadee coming to your feeder this morning also is named for obvious characteristics. Black-capped is what it is, and chickadee is what is says. The latter word is onomatopoeic — formed from a sound associated with what is named.

This chickadee's scientific name is Poecile atricapillus. Poecile is an old Greek word meaning varied; its original meaning pertained to embroidery. Atricapillus means black crown.

The house wren fussing and scolding in your yard takes its name from the Anglo-Saxon word wreanna. The word house was given to this bird because it often nests around dwellings (coincidentally, it readily will use a nest box or birdhouse).

Its family name is Troglodytes from the Greek words for hole and diver, as in diving in a hole, in this case a nesting cavity. Its species name is aedon, meaning a songstress. Aedon was the daughter of Pandereus, changed by the gods into a nightingale (another bird species).

Our robin, the American robin, was named by some of this country's original English settlers. There is a European bird named robin, about half the size as the robin in your yard, also with a red breast. That similarity was all it took for the name to stick on the North American species.

Bluebirds were called robins for a while (they, too, have a red breast), and towhees, also with red breasts, were known as ground robins. The robin snipe was a shorebird, either the red knot or the two dowitcher species, both of which show red. And the red-breasted merganser was called the sea robin.

Eventually, thank goodness, other names were given and kept.

The scientific name of the American robin is Turdus (Latin for thrush) migratorius (to migrate). Personally, I would name it red-breasted ground thrush.

Our blue jay is simply and directly named. Scientifically, it is Cyanocitta (from the Greek words for blue and jay) cristata (from the Latin for crested).

This two-name system for birds and other plants and animals was developed in the mid-18th century by a Swedish scientist named Karl von Linne, who became known by the Latinized form of his name, Linnaeus.

Common names of North American birds are the jurisdiction of the American Ornithologists' Union. A committee of that organization considers names and name changes, occasionally issuing proclamations about new names that make your bird field guides slightly out of date.

(Much of the information in this article came from two books, "The Dictionary of American Bird Names," revised edition, by Ernest A. Choate, and "The Birdwatcher's Companion" by Christopher Leahy.)

If you want to learn more, "Mrs. Moreau's Warbler: How birds got their names" recently was published by Guardian Faber. Author Stephen Moss tells good stories about bird names. He is English, and the book bends toward Great Britain, but his explanation of naming origins is entertaining and enlightening.

Read Jim Williams' birding blog at startribune.com/wingnut.