[333] With respect to feral pigeons—for Juan Fernandez, see Bertero in 'Annal. des Sc. Nat.,' tom. xxi. p. 351. For Norfolk Island, see Rev. E. S. Dixon in the 'Dovecote,' 1851, p. 14, on the authority of Mr. Gould. For Ascension I rely on MS. information given me by Mr. Layard. For the banks of the Hudson, see Blyth in 'Annals of Nat. Hist.,' vol. xx., 1857, p. 511. For Scotland, see Macgillivray, 'British Birds,' vol. i. p. 275; also Thompson's 'Nat. History of Ireland, Birds,' vol. ii. p. 11. For ducks, see Rev. E. S. Dixon, 'Ornamental Poultry,' 1847, p. 122. For the feral hybrids of the common and musk-ducks, see Audubon's 'American Ornithology,' and Selys-Longchamp's 'Hybrides dans la Famille des Anatides.' For the goose, Isidore Geoffrey St. Hilaire, 'Hist. Nat. Gén.,' tom. iii. p. 498. For guinea-fowls, see Gosse's 'Naturalist's Sojourn in Jamaica,' p. 124; and his 'Birds of Jamaica' for fuller particulars. I saw the wild guinea-fowl in Ascension. For the peacock, see 'A Week at Port Royal,' by a competent authority, Mr. R. Hill, p. 42. For the turkey I rely on oral information; I ascertained that they were not Curassows. With respect to fowls I will give the references in the next chapter.
[334] I have drawn out a long table of the various crosses made by fanciers between the several domestic breeds, but I do not think it worth publishing. I have myself made for this special purpose many crosses, and all were perfectly fertile. I have united in one bird five of the most distinct races, and with patience I might undoubtedly have thus united all. The case of five distinct breeds being blended together with unimpaired fertility is important, because Gärtner has shown that it is a very general, though not, as he thought, universal rule, that complex crosses between several species are excessively sterile. I have met with only two or three cases of reported sterility in the offspring of certain races when crossed. Von Pistor ('Das Ganze der Feld-taubenzucht,' 1831, s. 15) asserts that the mongrels from barbs and fantails are sterile: I have proved this to be erroneous, not only by crossing these hybrids with several other hybrids of the same parentage, but by the more severe test of pairing brother and sister hybrids inter se, and they were perfectly fertile. Temminck has stated ('Hist. Nat. Gén. des Pigeons,' tom. i. p. 197) that the turbit or owl will not cross readily with other breeds: but my turbits crossed, when left free, with almond tumblers and with trumpeters; the same thing has occurred (Rev. E. S. Dixon, 'The Dovecot,' p. 107) between turbits and dovecots and nuns. I have crossed turbits with barbs, as has M. Boitard (p. 34), who says the hybrids were very fertile. Hybrids from a turbit and fantail have been known to breed inter se (Riedel, Taubenzucht, s. 25, and Bechstein, 'Naturgesch. Deutsch.' B. iv. s. 44). Turbits (Riedel, s. 26) have been crossed with pouters and with jacobins, and with a hybrid jacobin-trumpeter (Riedel, s. 27). The latter author has, however, made some vague statements (s. 22) on the sterility of turbits when crossed with certain other crossed breeds. But I have little doubt that the Rev. E. S. Dixon's explanation of such statements is correct, viz. that individual birds both with turbits and other breeds are occasionally sterile.
[335] 'Das Ganze der Taubenzucht,' s. 18.
[336] 'Les Pigeons,' &c., p. 35.
[337] Domestic pigeons pair readily with the allied C. oenas (Bechstein, 'Naturgesch. Deutschlands,' B. iv. s. 3); and Mr. Brent has made the same cross several times in England, but the young were very apt to die at about ten days old; one hybrid which he reared (from C. oenas and a male Antwerp carrier) paired with a dragon, but never laid eggs. Bechstein further states (s. 26) that the domestic pigeon will cross with C. palumbus, Turtur risoria, and T. vulgaris, but nothing is said of the fertility of the hybrids, and this would have been mentioned had the fact been ascertained. In the Zoological Gardens (MS. report to me from Mr. James Hunt) a male hybrid from Turtur vulgaris and a domestic pigeon "paired with several different species of pigeons and doves, but none of the eggs were good." Hybrids from C. oenas and gymnophthalmos were sterile. In Loudon's 'Mag. of Nat. Hist.' vol. vii. 1834, p. 154, it is said that a male hybrid (from Turtur vulgaris male, and the cream-coloured T. risoria female) paired during two years with a female T. risoria, and the latter laid many eggs, but all were sterile. MM. Boitard and Corbié ('Les Pigeons,' p. 235) state that the hybrids from these two turtle-doves are invariably sterile both inter se and with either pure parent. The experiment was tried by M. Corbié "avec une espèce d'obstination;" and likewise by M. Manduyt, and by M. Vieillot. Temminck also found the hybrids from these two species quite barren. Therefore, when Bechstein ('Naturgesch. Vogel. Deutschlands,' B. 4, s. 101) asserts that the hybrids from these two turtle-doves propagate inter se equally well with pure species, and when a writer in the 'Field' newspaper (in a letter dated Nov. 10th, 1858) makes a similar assertion, it would appear that there must be some mistake; though what the mistake is I know not, as Bechstein at least must have known the white variety of T. risoria: it would be an unparalleled fact if the same two species sometimes produced extremely fertile, and sometimes extremely barren, offspring. In the MS. report from the Zoological Gardens it is said that hybrids from Turtur vulgaris and suratensis, and from T. vulgaris and Ectopistes migratorius, were sterile. Two of the latter male hybrids paired with their pure parents, viz. Turtur vulgaris and the Ectopistes, and likewise with T. risoria and with Columba oenas, and many eggs were produced, but all were barren. At Paris, hybrids have been raised (Isid. Geoffrey Saint Hilaire, 'Hist. Nat. Générale,' tom. iii. p. 180) from Turtur auritus with T. cambayensis and with T. suratensis; but nothing is said of their fertility. At the Zoological Gardens of London the Goura coronata and victoriæ produced a hybrid, which paired with the pure G. coronata, and laid several eggs, but these proved barren. In 1860 Columba gymnophthalmos and maculosa produced hybrids in these same gardens.
[338] There is one exception to the rule, namely in a sub-variety of the swallow of German origin, which is figured by Neumeister, and was shown to me by Mr. Wicking. This bird is blue, but has not the black wing-bars; for our object, however, in tracing the descent of the chief races, this exception signifies the less as the swallow approaches closely in structure to C. livia. In many sub-varieties, the black bars are replaced by bars of various colours. The figures given by Neumeister are sufficient to show that, if the wings alone are blue, the black wing-bars appear.
[339] I have observed blue birds with all the above-mentioned marks in the following races, which seemed to be perfectly pure, and were shown at various exhibitions. Pouters, with the double black wing-bars, with white croup, dark bar to end of tail, and white edging to outer tail-feathers. Turbits, with all these same characters. Fantails, with the same; but the croup in some was bluish or pure blue: Mr. Wicking bred blue fantails from two black birds. Carriers (including the Bagadotten of Neumeister), with all the marks: two birds which I examined had white, and two had blue croups; the white edging to the outer tail-feathers was not present in all. Mr. Corker, a great breeder, assures me that, if black carriers are matched for many successive generations, the offspring become first ash-coloured, and then blue with black wing-bars. Runts of the elongated breed had the same marks, but the croup was pale blue; the outer tail-feathers had white edges. Neumeister figures the great Florence Runt of a blue colour with black bars. Jacobins are very rarely blue, but I have received authentic accounts of at least two instances of the blue variety with black bars having appeared in England: blue jacobins were bred by Mr. Brent from two black birds. I have seen common tumblers, both Indian and English, and short-faced tumblers, of a blue colour, with black wing-bars, with the black bar at the end of the tail, and with the outer tail-feathers edged with white; the croup in all was blue, or extremely pale blue, never absolutely white. Blue barbs and trumpeters seem to be excessively rare; but Neumeister, who may be implicitly trusted, figures blue varieties of both, with black wing-bars. Mr. Brent informs me that he has seen a blue barb; and Mr. H. Weir, as I am informed by Mr. Tegetmeier, once bred a silver (which means very pale blue) barb from two yellow birds.
[340] Mr. Blyth informs me that all the domestic races in India have the croup blue; but this is not invariable, for I possess a very pale blue Simmali pigeon with the croup perfectly white, sent to me by Sir W. Elliot from Madras. A slaty-blue and chequered Nakshi pigeon has some white feathers on the croup alone. In some other Indian pigeons there were a few white feathers confined to the croup, and I have noticed the same fact in a carrier from Persia. The Java fantail (imported into Amoy, and thence sent me) has a perfectly white croup.
[341] 'Les Pigeons,' &c., p. 37.
[342] 'Treatise on Pigeons,' 1858, p. 145.