The doctrine that the chief domestic races are descended from several aboriginal species, implies that several species were formerly so thoroughly domesticated as to breed readily when confined. Although it is easy to tame most wild birds, experience shows us that it is difficult to get them to breed freely under confinement; although it must be owned that this is less difficult with pigeons than with most other birds. During the last two or three hundred years, many birds have been kept in aviaries, but hardly one has been added to our list of thoroughly reclaimed species: yet on the above doctrine we must admit that in ancient times nearly a dozen kinds of pigeons, now unknown in the wild state, were thoroughly domesticated.
THIRDLY.
Most of our domesticated animals have run wild in various parts of the world; but birds, owing apparently to their partial loss of the power of flight, less often than quadrupeds. Nevertheless I have met with accounts showing that the common fowl has become feral in South America and perhaps in West Africa, and on several islands: the turkey was at one time almost feral on the banks of the Parana; and the Guinea-fowl has become perfectly wild at Ascension and in Jamaica. In this latter island the peacock, also, "has become a maroon bird." The common duck wanders from its home and becomes almost wild in Norfolk. Hybrids between the common and musk-duck which have become wild have been shot in North America, Belgium, and near the Caspian Sea. The goose is said to have run wild in La Plata. The common dovecote-pigeon has become wild at Juan Fernandez, Norfolk Island, Ascension, probably at Madeira, on the shores of Scotland, and, as is asserted, on the banks of the Hudson in North America. (6/18. With respect to feral pigeons—for Juan Fernandez see Bertero in 'Annal. des Sc. Nat.' tome 21 page 351. For Norfolk Islands see Rev. E.S. Dixon in the 'Dovecote' 1851 page 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.' volume 20 1857 page 511. For Scotland see Macgillivray 'British Birds' volume 1 page 275; also Thompson 'Nat. Hist. of Ireland, Birds' volume 2 page 11. For ducks see Rev. E.S. Dixon 'Ornamental Poultry' 1847 page 122. For the feral hybrids of the common and musk-ducks see Audubon 'American Ornithology' and Selys-Longchamp 'Hybrides dans la Famille des Anatides.' For the goose Isidore Geoffroy St.-Hilaire 'Hist. Nat. Gen.' tome 3 page 498. For guinea-fowls see Gosse 'Naturalist's Sojourn in Jamaica' page 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, page 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.) But how different is the case, when we turn to the eleven chief domestic races of the pigeon, which are supposed by some authors to be descended from so many distinct species! no one has ever pretended that any one of these races has been found wild in any quarter of the world; yet they have been transported to all countries, and some of them must have been carried back to their native homes. On the view that all the races are the product of variation, we can understand why they have not become feral, for the great amount of modification which they have undergone shows how long and how thoroughly they have been domesticated; and this would unfit them for a wild life.
FOURTHLY.
If it be assumed that the characteristic differences between the various domestic races are due to descent from several aboriginal species, we must conclude that man chose for domestication in ancient times, either intentionally or by chance, a most abnormal set of pigeons; for that species resembling such birds as Pouters, Fantails, Carriers, Barbs, Short- faced Tumblers, Turbits, etc., would be in the highest degree abnormal, as compared with all the existing members of the great pigeon family, cannot be doubted. Thus we should have to believe that man not only formerly succeeded in thoroughly domesticating several highly abnormal species, but that these same species have since all become extinct, or are at least now unknown. This double accident is so extremely improbable that the assumed existence of so many abnormal species would require to be supported by the strongest evidence. On the other hand, if all the races are descended from C. livia, we can understand, as will hereafter be more fully explained, how any slight deviation in structure which first appeared would continually be augmented by the preservation of the most strongly marked individuals; and as the power of selection would be applied according to man's fancy, and not for the bird's own good, the accumulated amount of deviation would certainly be of an abnormal nature in comparison with the structure of pigeons living in a state of nature.
I have already alluded to the remarkable fact that the characteristic differences between the chief domestic races are eminently variable; we see this plainly in the great difference in the number of the tail-feathers in the Fantail, in the development of the crop in Pouters, in the length of the beak in Tumblers, in the state of the wattle in Carriers, etc. If these characters are the result of successive variations added together by selection, we can understand why they should be so variable: for these are the very parts which have varied since the domestication of the pigeon, and therefore would be likely still to vary; these variations moreover have been recently, and are still being accumulated by man's selection; therefore they have not as yet become firmly fixed.
FIFTHLY.
All the domestic races pair readily together, and, what is equally important, their mongrel offspring are perfectly fertile. To ascertain this fact I made many experiments, which are given in the note below; and recently Mr. Tegetmeier has made similar experiments with the same result. (6/19. 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 while 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 Gartner 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. Pistor ('Das Ganze der Feldtaubenzucht' 1831 s. 15) asserts that the mongrels from Barbs and Fantails are sterile: I have proved this to be erroneous, not only by crossing those 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. Gen. des Pigeons' tome 1 page 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 Dovecote' page 107) between Turbits and Dovecotes and Nuns. I have crossed Turbits with Barbs, as has M. Boitard (page 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. 4 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.) The accurate Neumeister asserts that when dovecotes are crossed with pigeons of any other breed, the mongrels are extremely fertile and hardy. (6/20. 'Das Ganze der Taubenzucht' s. 18.) MM. Boitard and Corbie (6/21. 'Les Pigeons' etc. page 35.) affirm, after their great experience, that the more distinct the breeds are which are crossed, the more productive are their mongrel offspring. I admit that the doctrine first broached by Pallas is highly probable, if not actually proved, namely, that closely allied species, which in a state of nature or when first captured would have been in some degree sterile if crossed, lose this sterility after a long course of domestication; yet when we consider the great difference between such races as Pouters, Carriers, Runts, Fantails, Turbits, Tumblers etc., the fact of their perfect, or even increased, fertility when intercrossed in the most complicated manner becomes a strong argument in favour of their having all descended from a single species. This argument is rendered much stronger when we hear (I append in a note (6/22. Domestic pigeons pair readily with the allied C. oenas (Bechstein 'Naturgesch. Deutschlands' b. 4 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.' volume 7 1834 page 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 Corbie ('Les Pigeons' page 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. Corbie "avec une espece d'obstination;" and likewise by M. Mauduyt, and by M. Vieillot. Temminck also found the hybrids from these two species quite barren. Therefore, when Bechstein ('Naturgesch. Deutschlands Vogel' 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 November 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. Generale' tome 3 page 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 victoriae 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.) all the cases which I have collected) that hardly a single well-ascertained instance is known of hybrids between two true species of pigeons being fertile, inter se, or even when crossed with one of their pure parents.
SIXTHLY.
Excluding certain important characteristic differences, the chief races agree most closely both with each other and with C. livia in all other respects. As previously observed, all are eminently sociable; all dislike to perch or roost, and refuse to build in trees; all lay two eggs, and this is not a universal rule with the Columbidae; all, as far as I can hear, require the same time for hatching their eggs; all can endure the same great range of climate; all prefer the same food, and are passionately fond of salt; all exhibit (with the asserted exception of the Finnikin and Turner which do not differ much in any other character) the same peculiar gestures when courting the females; and all (with the exception of Trumpeters and Laughers, which likewise do not differ much in any other character) coo in the same peculiar manner, unlike the voice of any other wild pigeon. All the coloured breeds display the same peculiar metallic tints on the breast, a character far from general with pigeons. Each race presents nearly the same range of variation in colour; and in most of the races we have the same singular correlation between the development of down in the young and the future colour of plumage. All have the proportional length of their toes, and of their primary wing-feathers, nearly the same,- -characters which are apt to differ in the several members of the Columbidae. In those races which present some remarkable deviation of structure, such as in the tail of Fantails, crop of Pouters, beak of Carriers and Tumblers, etc., the other parts remain nearly unaltered. Now every naturalist will admit that it would be scarcely possible to pick out a dozen natural species in any family which should agree closely in habits and in general structure, and yet should differ greatly in a few characters alone. This fact is explicable through the doctrine of natural selection; for each successive modification of structure in each natural species is preserved, solely because it is of service; and such modifications when largely accumulated imply a great change in the habits of life, and this will almost certainly lead to other changes of structure throughout the whole organisation. On the other hand, if the several races of the pigeon have been produced by man through selection and variation, we can readily understand how it is that they should still all resemble each other in habits and in those many characters which man has not cared to modify, whilst they differ to so prodigious a degree in those parts which have struck his eye or pleased his fancy.