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

secondXXXVIII.] THE BIRDS OF PARADISE. 425of the tail, and last of all, the red side plumes. I obtained aseries of specimens, illustrating tlie manner in which the extraordinaryblack tail ribands are developed, which is very remarkable.They first appear as two ordinary feathers, rather•shorter than the rest of t^ie tail ; the stage would nodoubt be tliat shown in a specimen of Paradisea apoda, in whichthe feathers are moderately lengthened, and Avith the webnarrowed in the middle ; the third stage is shown by a specimenwhich has part of the midrib bare, and terminated by a spatulateweb ; in another^the bare midrib is a little dilated and semicylindrical,and the terminal web very small ; in a fifth, thepei'fect black horny riband is formed, but it bears at its extremitya brown spatulate web ; while in another specimen, part ofthe black riband itself bears, on one of its sides only, a narrowbi'own web. It is only after these changes are fully completedthat the red side plumes begin to aj^pear.The successive stages of development of the colours andplumage of the Birds of Paradise are very interesting, from thestriking manner in which they accord with the theory of theirha\dng been produced by the simple action of variation, andthe cumulative power of selection by the females, of those malebirds which Avere more than usually ornamental.^ Variationsof colour are of all others the most frequent and the most striking,and are most easily modified and accumulated by man'sselection of them. We should expect, therefore, that the sexualdifferences of colour would be those most early accumulated andfixed, and Avould therefoj'e appear soonest in the young birds ;and this is exactly what occurs in the Paradise Birds. Of allvariations in the/o?-??i of birds' feathers, none are so frequent asthose in the head and tail. These occur more or less in everyfamily of birds, and are easily produced in many domesticatedvai'ieties, while unusual developments of the feathers of thebody are rare in the whole class of birds, and have seldom ornever occurred in domesticated species. In accordance withthese facts, we find the scale-formed plumes of the tlu'oat, thecrests of tlie head, and the long cirrhi of the tail, all fullydeveloped before the plumes which sirring from the side of tliebody begin to make tlieir appearance. If, on the other hand,the male Paradise Birds have not acquired tlieir distinctiveplumage by successive variations, but have been as they arenow from the moment they first appeared upon the earth, thissuccession becomes at the least unintelligible to us, for we can seeno reason why the changes should not take place simultaneously,or in a reverse order to that in which they actually occur.What is known of the habits of this bird, and the way inwhich it is captured by the natives, have already been describedat i^age 408.The Eed Bird of Paradise offers a remarkable case of restricted1 I have since arrived at the eonclusion that female selection is not the cause of thedevelopment of the ornamental plumes in the males. See my Barwinism, Chap. X.