528 SNAKES. 



advance from a situation of actual safety into one of 

 danger/ He has seen birds collect round the African 

 , tree snakes, particularly the Boomslange (described p. 407), 

 and fly to and fro, shrieking, until one of them almost 

 touches its lips.' Exactly so. We are not told as much, 

 but every one who knows anything of snake life will feel 

 quite sure that those tree snakes were making good use of 

 their delicate tongues in order to ascertain all they could 

 about those enticing shriekers ; and that the birds were 

 equally desirous of knowing what dainty in the shape of 

 worm or flitting creature that tongue might be. In the case 

 of the rattlesnake the ' fascinated' birds are probably enticed 

 by the insect they think they hear, as well as that they think 

 they see, in the supposed worm wriggling so temptingly and 

 vanishing so strangely. The snake remains rigidly still the 

 while, the only moving thing being that investigating 

 tongue. 



My observations at the Zoological Gardens first led me to 

 this conclusion. On the feeding days several years ago, 

 when watching to detect the ' fascination ' one had been led 

 to expect, I noticed that the birds — even the sparrows and 

 finches — were attracted by the tongue of the snake, and would 

 stop when hopping about the cage and look intently and 

 curiously on the vibrating tongue. Some would venture on 

 a closer inspection, and remain gazing, or would even peck 

 at it, until a movement of the snake told them that the 

 motionless object from which that wriggling thing protruded 

 was a living animal. Then they might hop away indifferently, 

 happily unconscious that what they had perched on as a 



■ ^ Zoology of South Africa. - 



