This section is from "The American Cyclopaedia", by George Ripley And Charles A. Dana. Also available from Amazon: The New American Cyclopędia. 16 volumes complete..
Bluebird, a North American bird of the genus sialia, order passcres, tribe denthrostres, and family luscinidce. The best known species, 8. Wilsonii (Swains.), is about 7 inches long and 10 inches in extent of wings; the bill is black, about half an inch long, and nearly straight; the plumage of the male is soft and blended, above of a bright azure blue, below yellowish brown, and the belly white; the female has the upper parts of a hue approaching leaden, with the rest like the male, though duller; the young have the head and back brownish. It is found in all parts of the United States, excepting perhaps some of the Pacific territories; it is very sprightly and familiar, and is always a welcome visitor. The nest is made either in a box prepared for it, or in any convenient hole in a tree; the eggs are from four to six, of a pale blue color. The food consists of various kinds of insects and spiders, and also the ripe fruits of the south. Its song is a soft agreeable warble, becoming plaintive as winter approaches, at which season most of them repair to the southern states.
There are two other species much resembling the above, S. Mexicana (Swans) and S. arctica (Swains.). The bluebird is one of the earliest of our spring songsters, and does good service to the agriculturist in destroying beetles, grasshoppers, grubs, wire-worms, and other similar pests; it rarely injures garden fruits, preferring those of the sumach and the wild cherry.
Bluebird (Sialia Wilsonii).