[242] For the Australian species, see Gould"s "Handbook," &c., vol. ii. p. 178, 180, 186, and 188. In the British Museum specimens of the Australian Plain-wanderer (_Pedionomus torquatus_) may be seen, shewing similar s.e.xual differences.
[243] Jerdon, "Birds of India," vol. iii. p. 596. Mr. Swinhoe, in "Ibis," 1865, p. 542; 1866, p. 131, 405.
[244] Jerdon, "Birds of India," vol. iii. p. 677.
[245] Gould"s "Handbook of the Birds of Australia," vol. ii. p.
275.
[246] "The Indian Field," Sept. 1858, p. 3.
[247] "Ibis," 1866, p. 298.
[248] For these several statements, see Mr. Gould"s "Birds of Great Britain." Prof. Newton informs me that he has long been convinced, from his own observations and from those of others, that the males of the above-named species take either the whole or a large share of the duties of incubation, and that they "shew much greater devotion towards their young, when in danger, than do the females." So it is, as he informs me, with _Limosa lapponica_ and some few other Waders, in which the females are larger and have more strongly contrasted colours than the males.
[249] The natives of Ceram (Wallace, "Malay Archipelago," vol.
ii. p. 150) a.s.sert that the male and female sit alternately on the eggs; but this a.s.sertion, as Mr. Bartlett thinks, may be accounted for by the female visiting the nest to lay her eggs.
[250] "The Student," April, 1870, p. 124.
[251] See the excellent account of the habits of this bird under confinement, by Mr. A. W. Bennett, in "Land and Water,"
May, 1868, p. 233.
[252] Mr. Sclater, on the incubation of the Struthiones, "Proc.
Zoo. Soc.," June 9, 1863.
[253] For the Milvago, see "Zoology of the Voyage of the "Beagle,"" Birds, 1841, p. 16. For the Climacteris and nightjar (Eurostopodus), see Gould"s "Handbook of the Birds of Australia," vol. i. p. 602 and 97. The New Zealand shieldrake (_Tadorna variegata_) offers a quite anomalous case: the head of the female is pure white, and her back is redder than that of the male; the head of the male is of a rich dark bronzed colour, and his back is clothed with finely pencilled slate-coloured feathers, so that he may altogether be considered as the more beautiful of the two. He is larger and more pugnacious than the female, and does not sit on the eggs.
So that in all these respects this species comes under our first cla.s.s of cases; but Mr. Sclater ("Proc. Zool. Soc." 1866, p. 150) was much surprised to observe that the young of both s.e.xes, when about three months old, resembled in their dark heads and necks the adult males, instead of the adult females; so that it would appear in this case that the females have been modified, whilst the males and the young have retained a former state of plumage.
[254] Jerdon, "Birds of India," vol. iii. p. 598.
[255] Jerdon, "Birds of India," vol. i. p. 222, 228. Gould"s "Handbook of the Birds of Australia," vol. i. 124, 130.
[256] Gould, Ibid. vol. ii. p. 37, 46, 56.
[257] Audubon, "Ornith. Biography," vol. ii. p. 55.
[258] "Variation of Animals and Plants under Domestication,"
vol. ii. p. 79.
[259] Charlesworth, "Mag. of Nat. Hist." vol. i. 1837, p. 305, 306.
[260] "Bulletin de la Soc. Vaudoise des Sc. Nat." vol. x. 1869, p. 132. The young of the Polish swan, _Cygnus immutabilis_ of Yarrell, are always white; but this species, as Mr. Sclater informs me, is believed to be nothing more than a variety of the Domestic Swan (_Cygnus olor_).
[261] I am indebted to Mr. Blyth for information in regard to this genus. The sparrow of Palestine belongs to the sub-genus Petronia.
[262] For instance, the males of _Tanagra aestiva_ and _Fringilla cyanea_ require three years, the male of _Fringilla ciris_ four years, to complete their beautiful plumage. (See Audubon, "Ornith. Biography," vol. i. p. 233, 280, 378.) The Harlequin duck takes three years (ibid. vol. iii. p. 614). The male of the Gold pheasant, as I hear from Mr. J. Jenner Weir, can be distinguished from the female when about three months old, but he does not acquire his full splendour until the end of the September in the following year.
[263] Thus the _Ibis tantalus_ and _Grus America.n.u.s_ take four years, the Flamingo several years, and the _Ardea Ludovicana_ two years, before they acquire their perfect plumage. See Audubon, ibid. vol. i. p. 221; vol. iii. p. 133, 139, 211.
[264] Mr. Blyth, in Charlesworth"s "Mag. of Nat. Hist." vol. i.
1837, p. 300. Mr. Bartlett has informed me in regard to gold-pheasants.
[265] I have noticed the following cases in Audubon"s "Ornith.
Biography. The Redstart of America" (_Muscicapa ruticilla_, vol. i. p. 203). The _Ibis tantalus_ takes four years to come to full maturity, but sometimes breeds in the second year (vol.
iii. p. 133). The _Grus America.n.u.s_ takes the same time, but breeds before acquiring its full plumage (vol. iii. p. 211).
The adults of _Ardea caerulea_ are blue and the young white; and white, mottled, and mature blue birds may all be seen breeding together (vol. iv. p. 58): but Mr. Blyth informs me that certain herons apparently are dimorphic, for white and coloured individuals of the same age may be observed. The Harlequin duck (_Anas histrionica_, Linn.) takes three years to acquire its full plumage, though many birds breed in the second year (vol.
iii. p. 614). The White-headed Eagle (_Falco leucocephalus_, vol. iii. p. 210) is likewise known to breed in its immature state. Some species of Oriolus (according to Mr. Blyth and Mr.
Swinhoe, in "Ibis," July, 1863, p. 68) likewise breed before they attain their full plumage.
[266] See the last footnote.
[267] Other animals, belonging to quite distinct cla.s.ses, are either habitually or occasionally capable of breeding before they have fully acquired their adult characters. This is the case with the young males of the salmon. Several amphibians have been known to breed whilst retaining their larval structure. Fritz Muller has shewn ("Facts and Arguments for Darwin," Eng. trans. 1869, p. 79) that the males of several amphipod crustaceans become s.e.xually mature whilst young; and I infer that this is a case of premature breeding, because they have not as yet acquired their fully-developed claspers. All such facts are highly interesting, as bearing on one means by which species may undergo great modifications of character, in accordance with Mr. Cope"s views, expressed under the terms of the "r.e.t.a.r.dation and acceleration of generic characters;" but I cannot follow the views of this eminent naturalist to their full extent. See Mr. Cope, "On the Origin of Genera," from the "Proc. of Acad. Nat. Sc. of Philadelphia," Oct. 1868.
[268] Jerdon, "Birds of India," vol. iii. p. 507, on the peac.o.c.k. Audubon, ibid. vol. iii. p. 139, on the Ardea.
[269] For ill.u.s.trative cases see vol. iv. of Macgillivray"s "Hist. Brit. Birds;" on Tringa, &c., p. 229, 271; on the Machetes, p. 172; on the _Charadrius hiaticula_, p. 118; on the _Charadrius pluvialis_, p. 94.
[270] For the goldfinch of N. America, _Fringilla tristis_, Linn., see Audubon, "Ornith. Biography," vol. i. p. 172. For the Maluri, Gould"s "Handbook of the Birds of Australia," vol.
i. p. 318.
[271] I am indebted to Mr. Blyth for information in regard to the Buphus; see also Jerdon, "Birds of India," vol. iii. p.
749. On the Anastomus, see Blyth, in "Ibis," 1867, p. 173.
[272] On the Alca, see Macgillivray, "Hist. Brit. Birds," vol.
v. p. 347. On the _Fringilla leucophrys_, Audubon, ibid. vol.
ii. p. 89. I shall have hereafter to refer to the young of certain herons and egrets being white.
[273] "History of British Birds," vol. i. 1839, p. 159.
[274] Blyth, in Charlesworth"s "Mag. of Nat. Hist." vol. i.
1837, p. 362; and from information given to me by him.
[275] Audubon, "Ornith. Biography," vol. i. p. 113.
[276] Mr. C. A. Wright, in "Ibis," vol. vi. 1864, p. 65.
Jerdon, "Birds of India," vol. i. p. 515.
[277] The following additional cases may be mentioned: the young males of _Tanagra rubra_ can be distinguished from the young females (Audubon, "Ornith. Biography," vol. iv. p. 392), and so it is with the nestlings of a blue nuthatch, _Dendrophila frontalis_ of India (Jerdon, "Birds of India,"
vol. i. p. 389). Mr. Blyth also informs me that the s.e.xes of the stonechat, _Saxicola rubicola_, are distinguishable at a very early age.
[278] "Westminster Review," July, 1867, p. 5.
[279] "Ibis," 1859, vol. i. p. 429, _et seq._
[280] No satisfactory explanation has ever been offered of the immense size, and still less of the bright colours, of the toucan"s beak. Mr. Bates ("The Naturalist on the Amazons," vol.
ii. 1863, p. 341) states that they use their beak for reaching fruit at the extreme tips of the branches; and likewise, as stated by other authors, for extracting eggs and young birds from the nests of other birds. But as Mr. Bates admits, the beak "can scarcely be considered a very perfectly-formed instrument for the end to which it is applied." The great bulk of the beak, as shewn by its breadth, depth, as well as length, is not intelligible on the view, that it serves merely as an organ of prehension.
[281] Ramphastos carinatus, Gould"s "Monograph of Ramphastidae."