54 APRIL 



young, because the time of their migration is so 

 early that they could not perform these duties 

 effectively, and therefore, purely from conscientious 

 motives, they think it best not to attempt to per- 

 form them at all. These persons even compare 

 the cuckoo favourably with the swift, whose migra- 

 tory instinct in autumn is so strong that it sometimes 

 leaves late broods to starve because it has a craving 

 to be on the wing. " The mother cuckoo, " they seem 

 to say, " is a pattern of birds ; rather than run 

 any risk for her offspring she resigns the parental 

 joys to which she is entitled. Could self-renuncia- 

 tion go farther ? " 



How is it that those birds in whose nests the 

 cuckoo leaves her young do not detect the fraud 

 and eject the egg or make another nest ? There 

 are many ornithologists who think that birds are so 

 deficient in the senses of touch and smell that they 

 cannot even perceive when they have been imposed 

 upon. It has also been said, contrariwise, that the 

 female cuckoo deposits in the nest that she has 

 selected for her offspring a few of her own feathers 

 before she leaves her egg, so that the foster-mother 

 may become accustomed to the cuckoo smell, and 

 will not detect any peculiarity in the egg when 

 it is placed there. But there have been cred- 

 ible cases of such offence being taken at the 

 intrusion that the victimised bird has actually built 

 a new floor over the cuckoo's egg and left it to 

 itself in the basement, while she has triumphantly 

 brooded a new family on the first storey. This 

 would surely show that she has possession of one 

 of the senses which would enable her to detect the 



