OCR Text |
Show 306. THE PlUNCII?LES OF PARI IE. BIRDS. With respect to the Fowl, I hMe received only one accot~nt,.. namely that out of 1001 chicl::ens of a highly-bred stock of Cochms,. reared during eight years by Mr. Stretch, 487 prove~ m~les and 514 females: i.e. as 94·7 to 100. In regard to domestiC p1geons tho~e is good evidence that the males are produced in. excess, ?r that the1r lives are longer; for those birds invariably pa1r, and smgle males, as Mr. Tegetmeier informs me, can always be purchased cheaper than females. Usually the two birds reared from the two ~ggs laid in the same nest consist of a male and female; but Mr. Harnson Weir, who has been so large a breeder, says that he has often bred two cocks from the same nest, and seldom two hens ; moreover the hen is generally the weaker of the two, and more liable to perish. With respect to birds in a state of nature, Mr. Gould and others 4"· are convinced that the males are generally the more numerous; and. as the young males of many species resemble the females, the latter would naturally appear to be the most numerous. Large numbers. of pheasants are reared by Mr. Baker of Leade~ball from eggs laid by wild birds, and he informs Mr. Jenner Weir that four or five · males to one female are generally produced. An experienced ob-server remarks4~ that in Scandinavia the broods of the capercailzie and black-cock contain more males than females; and that with the Dal-ripa (a kind of ptarmigan) more males than females attend the leks or places of courtship; but this latter circumstance is accounted for by some observers by a greater number of hen birds being killed by vermin. From various facts given by White of Selborne,46 it seems clear that the males of the partridge must be in considerable excess in the ·south of England; and I have been assured that this is the case in Scotland. Mr. Weir on enquiring from the dealers who receive at certain seasons large numbers of ruffs (Machetes• pugnax) was told that the males are much the most numerous. This same naturalist has also enquired for me from the birdcatchers, who annually catch an astonishing number of various small species alive for the London market, and he was unhesitatinglyanswered by an old and trustworthy man, that with the chaffinch the males are in large excess ; he thought as high as 2 males to- 44 Brehm (' Illust. Thierleben,' B. iv. s. 990) comes to the same con-clusion. 45 On the authority of L. Lloyd, '.Game Birds of Sweden,' 1867, p. 12,. :b32. 46 'Nat. Hist. of Selbourne,' letter xx.ix. edit. of 1825, vol. i. p. 139. CHAP. VIII. SEXUAL SELECTION. 307 1 female, or at least as high as 5 to 3.47 The males of the blackbird, he likewise maintained, were by far the most numerous whether caught by traps or by netting at night. 'I'hese state~ents may apparently be trusted, because the same man said that the sexes are about equal with the lark, the twite (Linaria montana), and goldfinch. On the other hand he is certain that with the co~mon. linnet, the femal_es preponderate greatly, but unequally durmg different years; durmg some years he has found the females to the males. as four to one. It should, however, be borne in mind, that the chief s~ason for catching birds does not begin till September, so that With some ~pecies partial mio-rations may have beo-un an~ the flocks at this period often consist of hens alone. Mr. Salvi~ pa1d particular attention to the sexes of the hummino--birds in Central America, and he is convinced that with most of the species the m~les are in exces.s ; thus one year he procured 204 specimens belongrng to ten species, and these consisted of 166 males and of 38 females. With two other species the females were in excess : but the proportions apparently vary either durino- different seasons or in different localities; for on one occasion the males of Campylopterus hemileucurus were to the females as five to two and on another occasion 48 in exactly the reversed ratio. As beari~o- on thi~ latter point, I may add, that Mr. Powys found in Corfu 0and Epnus the sexes of the chaflinch keeping apart, and "the females "by far the most numerous;" whilst in Palestine Mr. Tristram found " the male flocks appearing greatly to exceed the female in "number.':49 So. again with the Quiscalus mafor, Mr. G. Taylor 60 ~,ays, that I~, Flo~1da. there were" very few females in proportion io the m~les, whilst 1~ Honduras the proportion was the other way, the speCies there havmg the character of a polygamist. FISH. With Fish the proportional nnm hers of the sexes can be ascertained only by catching them in the adult or nearly adult state; and there 4 ~ Mr. Jenner ~eir received similar information, on making enquiries dunng the followmg year. To shew the number of chaffinches caught I may mention th~t in 1869 there was a match between two experts ; a~d one man caught m a day 62, and another 40, male chaffinches. The greatest nu~b,er ~v~r cau.~ht by one man in a single day was 70. Ib1s, vo~. n. P· 260, as quoted in Gould's 'Trochilidre' 1861 p. 52. F?r the foregomg proportions, I am indebted to M1·. Salvin' for a t~ble of Ius results. ~g 'Ibis,' 1860, p. 137; and 1867 p. 369. 50 'Ibis,' 1862, p. 137. ' X 2 |