The Malay archipelago : the land of the orang-utan ... - Wallace Online

xxvii.] THE NATURAL HISTORY OF THE MOLUCCAS. 303supports 257 species of land-birds as residents or regular immigrants,we must look upon the numbers already procured in thesmall and comparatively unknown islands of the Moluccas asindicating a fauna of fully average richness in this dei^artment.But when we come to examine the family groups which go tomake up this number, we find the most curious deficiencies insome, balanced by equally sticking redundancy in others. Thusif we compare the birds of the Moluccas with those of India, asgiven in Mr. Jerdon's work, we find that the three groups of theparrots, kingfishers, and pigeons, form nearly one-third of thewhole land-birds in the former, while tliey amount to only o??etwentiethin the latter country. On the other hand, such widespreadgroups as the thrushes, warblers, and finches, which inIndia form nearly one- third of all the land-birds, dwindle downin the Moluccas to one-fourteenth.The reason of these peculiarities appears to be, that theMoluccan fauna has been almost entirely derived from tliat ofNew Guinea, in which country the same deficiency and the sameluxuriance is to be observed. Out of the seventy-eightgenera in which the Moluccan land-birds may be classed,no less than seventy are characteristic of New Guinea, whileonly six belong specially to the Indo-Malay islands. Butthis close resemblance to New Guinea genera does not extend tothe species, for no less than 140 out of the 195 land-birds arepeculiar to the Moluccan islands, while 32 are found also in NewGuinea, and 15 in the Indo-Malay islands.^ These facts teachus, that though the birds of this group have evidently been derivedmainly from New Guinea, yet the immigration has notbeen a recent one, since there has been time for the greaterportion of the species to have become changed. We find, also,that many very characteristic New Guinea forms have notentered the Moluccas at all, while others found in Ceram andGilolo do not extend so far west as Bouru. Considering, further,the absence of most of the New Guinea mammals from theMoluccas, we are led to the conclusion that these islands are notfragments which have been separated from New Guinea, butform a distinct insular region, which has been upheaved independentlyat a rather remote epoch, and during all the mutationsit has undergone has been constantly receiving immigrantsfrom that great and jDroductive island. The considerable lengthof time the Moluccas have remained isolated is further indicatedby the occurrence of two peculiar genera of birds, Semiopteraand Lycocorax, which are found nowhere else.We are able to divide this small archipelago into two wellmarkedgroups—that of Ceram, including also Bouru, Amboyna,Banda, and Ke ; and that of Gilolo, including Morty, Batchian,1 A few species have been added in Bouru, Obi, Batchian, and other of the lessknown islands, by Mr. H. O. Forbes, Dr. Guillemard, and the Dutch and Germannaturalists, but they only sliglitly alter the figures, and do not at all afl'ect theconclusions here drawn.