The Encyclopedia Americana (1920)/Humming-birds
HUMMING-BIRDS, a family of small birds, the Trochilidæ, closely allied to the swifts, peculiar to America and almost exclusively tropical. They are distinguished by small size, iridescent plumage, long slender bill and the peculiar form of the tongue, which consists of a double tube tapering and separating at the tip into two externally lacerated sheaths, which contain the extensile portion. “The horns of the hyoid apparatus are greatly elongated, and pass round and over the back of the head, meeting near the top, and thence stretching in an ample groove to terminate in front of the eyes. This arrangement, analagous to that found in woodpeckers, allows the tongue to be suddenly protruded to a considerable distance, and withdrawn again in an instant.” This is a modification of parts adapted to food-getting habits, and is accompanied by others equally characteristic. Humming-birds feed almost entirely upon minute living insects, especially those that gather about flowers and loiter in the corollas, feeding upon the nectar: or dwell on the leaves and bark of plants and trees. Such honey as may be taken with them seems to be gratefully accepted, but the birds do not seek for, nor “suck” the nectar from flowers, as has been popularly supposed. They will dart from a perch and capture an insect like a flycatcher, but ordinarily they obtain them by poising upon their wings about leaves and in front of tree-trunks, picking up morsels, not with the mandables, but with the tongue; and still more frequently by searching flowers. As it is in the deep, tubular, sweet corollas of trumpet-creepers, orchids and similar great blossoms of tropical shrubs and vines that insects most abound so there does the humming-bird find its richest hunting-ground; and the long curved beaks of most species have been developed in the constant effort to penetrate to the nectarous depths of these deep blossoms; in truth, the head and half the tiny body may often be pulled into the flower, and in so doing gather and dispense pollen from flower to flower, so that humming-birds are important if not exclusive agents in the cross-fertilization of certain large flowered plants. (See Flowers, Fertilization of by Birds.) This method of obtaining food requires the power of sustaining themselves in the air in a fixed position while they explore leaves or blossoms, since no perch is available for their feet, which are small and weak at best. Hence humming-birds have developed lightness of body coupled with extraordinary muscularity and extent of wings, which in most species reach far beyond the root of the tail. These long narrow wings are operated by pectoral muscles that proportionately exceed in size those of any other bird, — even those of the chimney-swifts; and these huge muscles actuate remarkable short wing-bones, so that extreme rapidity of movement is possible, but it is accompanied by a loss of that power secured by the relatively longer alar bones of other birds. By this apparatus the humming-birds are able to beat the air with a rapidity which enables them to sand still, or to dart and dodge in pursuit of some agile insect, or in escaping danger, with a speed which defies human sight to trace; the moving wings at such times, indeed, appear only as a misty halo about the body of the bird, and make a loud humming noise. Most species have very long bills — frequently exceeding, and sometimes twice as long as the head; but some have short, awl-like beaks, with which they pierce the base of such flowers as are too deep for them.
A characteristic of humming-birds is that flashing beauty of plumage which long ago led to calling them the gems of the air, and is due mainly to the quality of the feathers, upon the surface of which are small scales that reflect the light in prismatic hues, giving an iridescent or metallic sheen to certain parts, especially the throat (gorget), comparable only to the shards of some beetles. Such brilliance, however, belongs only to the males, the females being uniformly more plainly dressed, though still highly colored. In many species, also, the males are further adorned with fanciful crests, mustaches, tufts, pendants of the chin and throat, “puffs” upon the legs, and especially with ornamental developments of the tail-feathers; and these they seem to take great delight in displaying for the admiration of the female, and the exasperation of rivals. They are extremely pugnacious, especially in the nuptial season, when constant and bitter fighting occurs, and their courage is so great that neither sex has any hesitation in attacking any bird that offends them or comes too near the nest, — even hawks and crows often flee ignominiously before the impetuous onslaughts of these little furies. On the other hand no bird is more fearless of man.
The nests of humming-birds are small cups of downy materials, sometimes resting upon the limb of a tree (as is the method with the common ruby-throat of the eastern United States; sometimes fastened in a crotch of a bush or of large leaves; or fastened to the tip of a pendant leaf, or in a bunch of hanging moss or foliage. The materials are adapted to the place in color and appearance, and further concealment is gained by coating the structure with lichens, or bits of bark, or with cone-scales, as is the habit of the familiar Calliope hummer of California, which nests in pine trees. The eggs of all species are only two in number and purely white.
The family is exclusively American, and is represented from Labrador and southern Alaska to Patagonia; but the more vagrant species are few, and withdraw in winter toward the equator. About 125 genera with some 500 species are recognized by ornithologists. Nine-tenths of them belong to the Amazon and Orinoco valleys, or to the lowlands of Central America; yet some species habitually spend the summer on high mountains. The variety decreases northward, but nearly 20 species reach the boundary of the United States and several are regularly present in summer west 01 the great plains as far north as southern Alaska. One species wanders over the whole country, and is abundant in the Eastern States. This is the ruby-throat (Trochilus colubris). It is about three and one-half inches long. The whole upper part, sides under the wings, tail coverts and two middle feathers of the tail are rich golden green; the tail is forked, and, as well as the wings, of a deep brownish purple; the bill and eyes black; but what constitutes their chief ornament is the splendor of the feathers on the throat of the male, which are ruby-red, and gleam like a great jewel. The females and immature young lack this gorget.
The Anna humming-bird (Calypte annæ), with crown and throat glittering purplish-pink; the broad-tailed (Selasphorus platycercus), green, with pink throat; the rufous (S. rufus), back reddish brown, gorget red; Allen's (S. alleni), crown and back green, tail rusty; and the calliope (Stellula calliope), very small, green above, throat purple-pink, mixed with white; are more or less common and widespread summer visitors to the Pacific slope.
Bibliography.— Jardine, ‘Naturalists' Library’ (Vols. I and II, Edinburgh 1833); Lesson, ‘Histoire Naturelle des Colubris’ (1830); Gould, ‘Monograph of the Trochilidæ’ (5 vols., 1850-95); Mulsant and Verreaux, ‘Histoire Naturelle des Oiseaux-Mouches ou Colubris’ (4 vols., 1876); Ridgway, ‘The Humming-birds’ (Am. Rept. United States National Museum for 1890, Washington 1892).