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Show 54 SEXUAL SELECTION : BIRDS. PAR1'Il'. the sake of charming the female, is not at all incompatible ; and, indeed, might have been expected to go· toaether, like decoration and pugnacity. Some authors, h~wever, argue that the song of the male cannot serve to charm the female, because the females of some few species, such as the canary, robin, lark, ~nd bullfinch, especial1y, as Bechstein remarks, w~en m a . state of widowhood, pour forth fairly melodwus stram~. In some of these cases the habit of singing may be m part. attributed to the females having been highly fed and confinecl 32 for this disturbs all the usual functions connected ,~ith the reproduction of the species. _Many instances have already been given of the partial transference of secondary masculine characters to the female,. so that it is not at all surprising that the females of some species should po sess the power of song. It has also been argued, that the song of the ma~e caun?t serve _as a charm because the males of c01tam spccws, for m-stance, o' f the robin, sing during the autumn. ~ B ut nothing is more common than for ::mirnals to take pleasure iu practising whatever instinct they follow at o~her times for some real good. How often do we see bn·~s. which fly easily, gliding and sailing thr~ugh the mr obviously for pleasure. 'fhe cat plays w1th the captured mouse, and the cormorant with the captured fish. The weaver-bird (Ploceus), when confined in a cage, amuses itself by neatly weaving blades of grass between. tl1e wires of its cage. Birds which habitually fight during the breeding-season are generally rea_dy_ to fight at all times ; and the males of the caperc:ulZie sometimes hold their balzens or leks at the usual place of l2 D. Barrington, 'Phil. Tnmsnct.' 1773, p. 262. Bechstein, 'Stuben vogel,' 18-1:0, s. 4. 33 This i~ likewise the cnsc with the water-ouzel, sec Mr. IIcpburu , in the 'Zoologist,' 1845-1846, p. 1068. CHAP. XHT. VOCAL MUSIC. 55 asse~b.lage during the autumn.34 Hence it is not at all sur~nsmg that male birds should continue singing for tbmr own amusement after the season for courtship is over. Singing is to a certai_n extent, as shewn in a previous c~apter, an art, and 1s much improved by practice. Bu·ds can be taught various tunes, and even the unmelodious sparrow has learnt to sina like a linnet ~rh ey. acqm·r e the song of their fostbe r-parcnts,3 • ; and somet1mes that of their neighbours.36 All the common songsters belong to the Order of Insessores, and their vocal organs are much more complex than those of most other birds; yet it is a singular fact that some of the Insessores, such as ravens, crows, and magpies, pos e~ s the proper apparatus/37 though they never sing, nnd do not naturally modulate their voices to any areat extent. Iluuter asserts 38 that with the true son ~ters the ~usc]es of the larynx are stronger in the ~ales ~han m :he femal:s; but with this slight exception there 1s no chfferenre m the vocal organs of the two sexes although the males of most species sina so much bett : d . 0 81 an more contmuously than the females. It is rem~rkable that only small birds properly sing. The Austrahan genus Menura, however, must be excepted; for the Menura Alberti, which is about the size of a half-grown turkey, not only mocks other birds but "its own whistle is exceedingly beautiful and varied." The .males co?grega~~ and form "corroborying places," whe1e they smg, I"alsmg and spreading their tails like :: L. L~oyd, 'G_a~e Birds of Sweden,' 1867, p. 25. a~ Bar~·mgton, 1b1d. p. 2_64. Bec~stein, ibid. s. 5. 3 .] D~Ie:u de In Malle gtvcs a cunous instance (' Annalcs des Sc. Nat: :I( scr~es, Z?olog. tom. x. p. 118) of some wild. blackbirds in his garden 111 Par~s whwh naturally learnt from a Cl1'•ecl Lird a republican air 37 B1shop in' Todd' c 1 f o • 33 • ~ yc O~J. o A_nat. nnd Phys.' vol. iv. p. 1496. As stated by Barnngton 111 'Philosoph. Transact.' 1773, p. 262. |