1917-] Breeding-habits of the Cuckoo. 223 



(B) Further data regarding the nesting-habits of the 

 Cow-birds of America. 



Major Bendire gives the following instances of mistakes 

 and imperfections in the procreant instinct of the Cow- 

 birds : — 



(1) The eggs are sometimes dropped on the ground and 

 wasted. 



(2) They are placed in forsaken nests. 



(8) They are laid after incubation of the eggs has begun. 



(4) One female lays several eggs in the same nest. 



(5) Several females lay in the same nest. 



[Q) The male and female of some species destroy their 

 own eggs by picking holes in them and sucking the 

 contents. 



On the other hand, he says that their eggs possess the 

 following advantages : — 



(1) The vitality of the embryo is very great and it survives 

 after the other eggs in the nest have become addled, and eggs 

 buried in the lining of nests have been found with the young 

 ready to hatch, though as the young in the nest itself were 

 some fonrteen days old the Cow-bird's e^^ must have been 

 about six weeks old and probably was incubated by the heat 

 of the other young. 



(2) They are usually larger and have a harder shell. 



(3) They take only some eleven and a half days to hatch as 

 against fourteen to sixteen days in the case of other similar 

 species, and consequently have a chance if deposited in 

 nests in which the other eggs are incubated. 



