So APRIL 



British Birds, has given carefully coloured illustra- 

 tions of as many as fifteen varieties, ranging from 

 blue to brown and from blotched to spotted speci- 

 mens. Controversy seems to rage round this fact, 

 one naturalist asserting that the coloration is an 

 hereditary faculty ; that each female cuckoo lays 

 a particular type of egg ; and that the cuckoo 

 which lays blue eggs takes care to deposit them 

 in the nest of some blue-egg-laying species, and 

 so on. Another authority maintains that the blue 

 eggs of the cuckoo are more frequently found in 

 nests of birds with brownish eggs than in those 

 with eggs of blue, so that the specialised colour- 

 ing is misleading and purposeless. Another, again, 

 seems to think that the variation is purely accidental, 

 and that, if it were not, the cuckoo mother would 

 be taking upon herself a great deal of unnecessary 

 trouble, since the foster parents of many species 

 are so easily deceived, and make no objection 

 whatever to receiving and hatching the alien. This 

 naturalist is also of opinion that other causes must 

 be looked for to account for the variation, such as 

 the age of the bird, or defective organisation. 



Why does the cuckoo rely on foster-parents 

 for the upbringing of her young? There are 

 some charitably minded ornithologists who would 

 fain persuade us that her stomach is so placed as 

 to get in the way when she would sit, and that 

 brooding is in consequence impossible. Yet there 

 are well-authenticated cases of cuckoos hatching 

 out their own young, and the night-jar, which 

 suffers from a similar anatomical disability, never 

 tries to shirk her maternal duties. Others imagine 



