APRIL 55 



fraud. Dr. Japp, for his part, declares that the 

 senses of touch and smell in birds are very keen ; 

 the coot, he tells us, will not sit upon ducks' eggs. 

 And he narrates a story of an ornithologist who 

 made experiments with a woodpecker's nest. He 

 cut a circular piece out of the tree just below the 

 nest and, extracting the woodpecker's egg, he 

 substituted for it a thrush's egg. Then he filled 

 up the hole with the bung, colouring it over exactly 

 like the bark of the tree. The woodpecker stuck 

 to her nest, and when she had laid four more eggs 

 he took out the bung, and found that the thrush's 

 egg had been rolled out of the nest into a recess, 

 although the place was quite dark, and detection 

 through the sense of sight must have been im- 

 possible. 



If Nature has armed the coot and the wood- 

 pecker with a sense so keen as to prevent their 

 incubating alien eggs, why has she not provided 

 other smaller birds with this instinct ? For them 

 even more than for the larger birds it would seem 

 an important gift, their nests being more liable to 

 intrusion ; so that the coot and the woodpecker 

 and a few others are given an instinct that is 

 practically never called into exercise, while on 

 birds which need this instinct more Nature has 

 apparently failed to bestow it. 



But Dr. Japp does not believe that Nature has 

 treated these little birds badly. He thinks that 

 their senses are no less keen than those of the 

 others, and that for a few instances recorded of 

 a bird building over a parasitical egg there are pro- 

 bably countless others which escape notice. If, as 



