i 9 4 SKETCHES OF BIRD LIFE. 



assumes the colour and markings of those before 

 her. This is not, however, supported by facts. 

 For the egg of a Cuckoo is frequently found with 

 eggs which do not in the least resemble it (e.g. 

 those of the Hedge Sparrow) ; or with eggs which 

 from the nature of the nest could not have been 

 seen by the Cuckoo (as in the case of the Redstart, 

 Wren, or Willow Wren) ; or deposited in a nest 

 before a single egg had been laid therein by the 

 rightful owner. Again, two Cuckoo's eggs of a 

 different colour have been found in the same nest. 

 If both were laid by one bird, we have a proof that 

 the same Cuckoo does not always lay eggs of the 

 same colour; if laid by different birds, then the 

 Cuckoo is not so impressionable as has been sup- 

 posed. 



What really takes place, we believe, is this : 

 The Cuckoo lays her egg upon the ground ; the 

 colour of the egg is variable according to the con- 

 dition of the ovary, which depends upon the age of 

 the bird, the nature of its food, and state of health at 

 the time of oviposition. With her egg in her bill, the 

 bird then seeks a nest wherein to place it. We are 

 not unwilling to accept the suggestion that, being 



