Page:Popular Science Monthly Volume 15.djvu/386

372 designate myself by such a periphrasis), is far more interested in the modifications which feathers undergo, after they have become feathers, than in those which they undergo before reaching that stage of their development. For the infinite variety of coloring, the exquisite tones of metallic sheen, the graceful arrangements of crests, tufts, plumes, and lappets, which render birds such conspicuous objects in our museums or gardens, are all of them due to the pigments or shapes of feathers, and all of them have apparently been produced by the voluntary choice of beautiful mates among the birds themselves.

The modifications of feathers thus originated form, of course, a clew to the tastes of the various birds which possess them; because each species will naturally select such mates as best satisfy its ideas of the beautiful, and so will transmit the admired qualities to its descendants. It is a remarkable fact that the tastes of many birds, indirectly disclosed in such a manner, coincide very closely with the tastes of mankind at large.

Not all birds, however, exhibit equally these æsthetic preferences. Some large families, like those of the hawks, eagles, owls, and nightjars, are noticeable neither for beauty of color nor for richness of song. Other classes, again, like those of our own English hedge-birds, seem rather musical than chromatically inclined in their tastes. As a rule, we may say that birds of prey and nocturnal birds are very deficient in aesthetic feeling, all their energies being apparently directed to swiftness of pursuit and skill in hunting; while, on the other hand, small seed-eating birds, and those which live on little insects or other minute animals, generally expend all their æsthetic sentiment on the faculty of song. But only those birds which live upon fruits, or the mixed nectar and insects extracted from flowers, usually possess brilliant colors.

I have already more than once pointed out to the readers of the "Cornhill Magazine" the probable reason for this peculiar connection. The eyes of fruit-eating or flower-feeding animals become specially adapted to the stimulation of colored light, and therefore the creatures become capable of receiving special pleasure from such sources. Accordingly, those among their fellows which displayed brilliant colors would prove most attractive, and would be chosen as mates for their beauty. I have instanced before, among the flower-feeding species, the numberless varieties of humming-birds, and the almost equal profusion of sun-birds, to which we may add a few other minor forms, such as the brush-tongued lories; while among the fruit-eaters, the parrots, macaws, cockatoos, toucans, barbets, nutmeg-pigeons, fruit-pigeons, chatterers, and birds-of-paradise, may stand as cases in point. But it will be more interesting here to glance briefly at the various modes in which these colors are produced than to extend the list of species which display them.