1917-] BreetUiui-habits of the Ciickoo. 221 



19. At times a vigorous resistance is met with from the 

 owners of the nest, resulting in the Cuckoo's egg being 

 destroyed, but usually it is accepted and the young Cuckoo 

 reared with extraordinary devotion by its foster-parents. 

 In this connection it is interesting to learn that some 

 species, such as the Indigo Bunting, will often desert their 

 nests if the Cow-bird's egg be removed, but do not appear 

 to mind the loss of one or two of their own eggs. 



20. *Probably the Cuckoo inserts its egg, whenever 

 possible, in the absence of the lawful owners of the nest. 



21. Neither the ovary nor the egg-development of the 

 Cuckoo presents any abnormality in comparison to other 

 species. 



22. Shortly after being hatched the young Cuckoo ejects 

 all its companions from the nest, and if by chance two 

 young Cuckoos are hatched in the same nest the weaker 

 is ejected. Exceptions occasionally occur, due probably to 

 the nest being in a deep hole, etc., and ejection not being 

 possible. 



23. *The female Cuckoo appears, at least at times, to take 

 some interest in the future development of her eggs, subse- 

 quently removing other eggs from the nest, and assisting 

 on occasions in the process of ejection and even in feeding 

 her young. 



In conclusion, I wish to state clearly that this paper has 

 not been written with any idea of minimising the important 

 results achieved by Dr. Key and others, who devoted endless 

 labour to trying to throw some further light on this involved 

 question and to whose efforts much of our knowledge is due. 

 My object has been to endeavour to show that the problem 

 is still unsolved and to try to interest others in the subject. 

 The difficulties in obtaining reliable information are so great 

 that it seems that success can only be achieved by united 

 efforts and by ensuring, so far as possible, against any chance 

 clues beinsr lost. 



