THE present volume completes the enumeration and description of the Birds of British India, whilst corrigenda, addenda and synonomy will be given in a seventh and final volume.
The number of species described by the various authors who have written on the Birds o£ India since 1864, when Jerdon's first edition appeared, shows what great progress has been made in our studies of the Avifauna. In 1864 Jerdon included in his three volumes 1016 species. It must be remembered, however, that Jerdon dealt with a very much smaller area in his work, as he omitted parts of Assam and Burma. Hume provisionally named 1788 species in his Catalogue of the year 1879, many of which he eventually rejected and 74 of which he regarded as doubtful. This left a total of 1608 species which he considered to be satisfactorily determined, all of which, it should be noted, were regarded as full species. Hume, however, whilst fully appreciating the value of geographical variation in birds, had not passed beyond the binomial system of nomenclature and, therefore, whenever this variation was obvious, the bird was raised to the rank of species, though frequently Hume noted that the differences between it and its nearest allies were racial only.
In the first edition of the Avifauna written by Blanford and Oates in 1898 the area covered was extended to include all Burma and Assam, 1616 species were described and 11 added in an appendix, giving a total of 1627. In this work also subspecies were not recognized as such. Consequently minor differences, however constant and distinct, were again passed over as valueless, whilst those which were greater were considered sufficient to give the geographical race the position of a full species. The present work, in which for the first time subspecies are recognized under the trinomial system of classification, contains 2293 species and subspecies. In many cases, forms which Hume named and then rejected have had to be resuscitated, frequently because they represent definite geographical variations as already shown by him. Thus, although not worthy of the status of a full species because they grade into other forms in connected areas, they yet could not possibly be ignored and must take their proper positions as subspecies.
I have already dealt in some detail with the classification in the present edition when commenting on the characters under the headings of the various orders, suborders and families, and it is therefore unnecessary for me to add much here. Briefly 1 have acted on the principle that a classification already in use should not be altered for another classification equally good merely for the sake of change. I have, therefore, so far as is possible, followed Blanford and Oates in their classification unless this has been definitely proved to be wrong.
In the volumes dealing with the Pico-Passeres, I have been greatly indebted to the work of Mr. W. P. Pycraft,. whilst in this, the VIth Volume, I have followed in great part the arrangement of Orders, Families and Genera suggested by Dr. P. R. Lowe as a result of his researches. In regard to the Charadriiformes. especially, his system seems to be a distinct advance upon anything previously attempted. In consequence, the reader will find more drastic changes in this great order than have been made in any of the others. Every system, however, is merely the basis for further research work; many of Dr. Lowe's changes are suggestions rather than final opinions, and neither he nor I imagine that his system will not require further alteration and improvement.
It is quite possible that further research work will prove that many anatomical characters, upon which at present great reliability is placed, are of much less value than is believed to be the case, whilst some of these, so-called, deep-seated characters may prove to be of less importance than others which now are considered superficial. One such character which is very obvious is that of colour and colour-pattern, which in my opinion may ultimately prove to be a character of the utmost importance in the definition of genera and perhaps even of families. Oates, in the first edition of the Avifauna, had already recognized the importance of this character, employing it as one of the means of differentiating between the Passerine genera. Dr. Lowe, as well as many other systematists, has also emphasized the value of the plumage-pattern in the young of birds, and this character is now generally accepted as a great aid in determining the position of the parent bird. Oates used the colour of the young as compared with that of the adult as the guiding characteristic in his Passerine families. Further work in museum and field has endorsed his use of this feature but, although Dr. C. B. Ticehurst has already contributed greatly to our knowledge in this respect, it must be remembered that, as regards India, much work yet remains to be done in the study of juvenile and nestling plumage. This is a work in which the field naturalist can do far more than the purely museum Systematist. It is therefore to be hoped that those who read the present work will do their utmost to fill the many gaps in this volume which exist in this respect.
Another point to which I would draw the attention of the field naturalist is the fact there are still some three hundred species and subspecies of birds of whose habits and nidification we know nothing. Again, our recorded knowledge of vernacular names is curiously meagre, many naturalists being satisfied to say that Indians have only class names for birds and do not distinguish between allied species. It is true that Indians do so lump many species under one family name, but it will be found that in most cases the various species are recognized and differentiated by the addition of a descriptive prefix. It would be equally true to say that Englishmen do not distinguish one duck from another because they call them all ducks.
The present volume contains the Game-Birds, Pigeons, Bustard-Quails, the immense number of birds generally known as Water-Birds and Waders, together with the Flamingoes, Ducks and their allies, and the Grebes. Even amongst the birds so well known as the Ducks and Geese much yet remains to be learnt in regard to moults, eclipse plumage and various other points in their life-history, whilst it is possible that other species and subspecies occur which have so far been overlooked. I would therefore again emphasize the fact that it is to the field naturalist we must look for the elucidation of many of these questions.
I have to acknowledge the courtesy of the Editors of the Bombay Natural History Journal' in allowing me to use the three plates depicting the Bills, Wings and Tails of the Snipes, showing the differences between the various species far better than the most lengthy descriptions.
My work of writing the present volume and the five which have already appeared has been carried out almost entirely at the British Museum, and I would most sincerely thank the authorities in the Bird Room for their unfailing patience, courtesy and help, without which the volumes would have been long delayed. To Dr. P. Lowe and to Mr. N. Kinnear. I am indebted for constant help in every way, and to Mr. T. Wells for the infinite patience with which he has endured the endless interruptions I have caused to his normal work.
In conclusion, I would ask my readers to remember that these same volumes have been written during a period in which naturalists have been concentrating on the subdivision of species into geographical races and on corrections in nomenclature. Had I waited to work out as minutely as I could have done such details in the case of every bird described, it is probable that the first volume would be still under preparation. Nomenclature and geographical variations must be the work of many authors and perhaps of several generations, so that complete stability cannot be expected during our days. At the same time, it is hoped that the six volumes will prove a useful basis upon which systematists can build, and it is believed that the comparative speed at which they have been produced will assist in this work more than would have been the case had greater delay brought the volumes some steps nearer perfection. As regards the Field Naturalist, I hope that it will show him how much there is left for him to do and will also prove to him how entirely interdependent the man in the museum and the man in the field are upon one another.
E. C. STUART BAKER.
March 28th, 1929.