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Show 5G SEX.UAL SELECTION : BIRDS. peacocks nnd <lrooping their wiogs.39 It is also remarkable that the birds which sing are rarely decorated with brilliant colours or other ornaments. Of our British birds, excepbng the bullfinch and goldfinch, the best songsters are plain-coloured. The king-fisher, bee-eater, roller, hoopee, woodpeckers, &c., utter harsh cries ; and the brilliant birds of the tropics are hardly ever songsters.' 10 Hence bright colours and the power of song Reem to rep1o.ce each other. \Ve can perceive that if the plumage did not vary in brightness, or if bright colours were dangerous to the species, other means would have to be employed to charm the females ; and the \oice being rendered melodious would offer one such means. In some birds the vocal organs differ greatly in the two sexes. In the Tetrao ct~pido (fig. 39) the male has two bare, orange-coloured sacks, one on each side of the neck ; and these are largely inflated when the male, during tho breeding-season, makes a curious hollow sound, audible at a great distance. Auuubon proved that tho sounrl was intimately connected with this apparatus, which reminds us of the air-sacks on each side of the mouth of certain male frogs, for he found that the sound was much diminished when one of the sacks of a tame bird was pricked, and when both were pricked it was altogether stopped. rrhe female has "a some" what similar, though smaller, naked space of skin on " the 11eck; but this is not capable of inflation." 41 The 39 Gould, 'Handbook to the Birds of Australia,' vol. i. 18G5, p. 308- ::110. See also Mr. T. W. Wood in the' Student,' April, 1870, p. 125. 40 Sec rcmnrks to this effect in Gould's 'Introduction to the Trochi-lidro,' 18Gl, p. 22. 41 'The Sportsman and Naturalist in Canada,' by Major W. Ross King, 1866, p. 144-HG. Mr. T. W. Wood gives in the 'Student' (April, 1870, p. llG) an excellent account of the attitude and habits of this bird during its courtship. He states that the car-tufts or neckplumes ore erected, so thnt they meet over the crown of the bend. CrrAr. XJU. VOCAL lllUSIC. 57 male of another kind of grouse (Tetra . ~vhil·lst cm_u-ting the female, llas his "~m:roypell~laos~an'us), 'p 1a(Yus fl t d t w mso- " as t{IC ~:d a ~" o ~prodigious size, fully half as large y' an he then utters vru:·l·ous t~; ra t"m g, |
