The Courting of Birds 



display made by the plainly-coloured male of the 

 Indian spotted-billed duck (Anas poecilorhyncha), 

 which has no such beauties to show, we seem to 

 be taken back to a period in the history of these 

 ducks when both had nothing to show off, but 

 yet had this characteristic way of expressing their 

 emotions. 



An analogous case is found in the vibrating 

 of the tail in certain snakes. In the case of the 

 rattlesnakes, this action of course sounds the 

 rattle, but an analogous quivering of the tail is 

 found in the allied vipers of the genus Trime- 

 resurus, which have nothing in the shape of a 

 rattle. Here a previously-existing gesture has 

 come in very conveniently for the utilisation of 

 a new organ. 



I must admit that in this case one would 

 expect the Carolina drake to show off like his 

 ally the Mandarin ; but then these two lovely 

 ducks, although undoubtedly allied, are not such 

 near relatives as the mallard and spotted-bill, or 

 the gold and Amherst pheasants, so that it is 

 quite possible for them to have had different 

 methods of displaying long before the drakes 

 acquired their peculiar decorations. The species 

 certainly inhabit widely different countries, the 

 one belonging to Eastern Asia and the other 

 to North America, and they are notoriously un- 

 willing to interbreed, although ducks, as a rule, 



