. The descent of man, and selection in relation to sex. Evolution; Heredity; Human beings; Natural selection. CHAP. VOCAL MUSIC. 391 British birds, excepting the bullfinch and goldfinch, the best songsters are plain-colored. The kingfisher, bee-eater, roller, hoopoe, woodpeckers, etc., utter harsh cries ; and the brilliant birds of the tropics are hardly ever songsters.*^ Hence bright colors and the power of song seem to replace each other. We can perceive that if the plumage did not vary in brightness, or if bright colors were dangerous to the species, other means. Fig. 39.—Tctrao cupi
. The descent of man, and selection in relation to sex. Evolution; Heredity; Human beings; Natural selection. CHAP. VOCAL MUSIC. 391 British birds, excepting the bullfinch and goldfinch, the best songsters are plain-colored. The kingfisher, bee-eater, roller, hoopoe, woodpeckers, etc., utter harsh cries ; and the brilliant birds of the tropics are hardly ever songsters.*^ Hence bright colors and the power of song seem to replace each other. We can perceive that if the plumage did not vary in brightness, or if bright colors were dangerous to the species, other means. Fig. 39.—Tctrao cupido : male. (T. W. Wood.) would be employed to charm the females; and melody of voice offers one such means. In some birds the vocal organs differ greatly in the two sexes, In the Tetrao cupido (fig. 39) the male has two bare, orange- colored sacks, one on each side of the neck ; and these arc largely inflated when the male, during the breeding season, makes his curious hollow sound, audible at a great distance. Audubon proved that the sound was intimately connected with this apparatus (which reminds us of the air-sacks on each side ^ «o See remarks to this cflfect in Gould's " Introduction to the ; 1861, jx <«. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Darwin, Charles, 1809-1882. New York Hurst
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Keywords: ., bookcentury1800, bookdecade1870, booksubjecthumanbeings, bookyear
