114 SUMMER BIRDS 



to eject them one after another from the home so 

 patiently and skilfully constructed by their true parents. 

 Four, five, or six legitimate babes are murdered in order 

 that one sturdy alien shall be reared. 



A further feature in the cuckoo's procedure is not so 

 easily explained; in fact, it is better to own that, at 

 present, no satisfactory explanation has been offered. 

 Mr. Bidwell has prepared a list of 120 species of birds 

 in the nests whereof cuckoo eggs have been found. 1 

 In very many cases these eggs are coloured closely in 

 imitation of those of the intended foster. parent. The 

 extraordinary variety of colouration is well illustrated in 

 Plate 49 of Seebohm's Eggs of British Birds, where ten 

 specimens are represented, varying from pure sky-blue, 

 found in a redstart's nest, through different hues and 

 marking to deep russet mottle, closely resembling some 

 forms of the tree-pipit's egg. As it is difficult to 

 believe that the female cuckoo has the power of paint- 

 ing her eggs to match those in the nests wherein she 

 chooses to place them, it has been inferred that the 

 foster parent is preferred whose eggs most nearly 

 resemble those which the cuckoo has to dispose of. 

 But this problem, obscure in all its aspects, is still a 

 long way from elucidation. 



The career of the cuckoo, then, is one long, persistent, 

 and habitual violation of the sixth, seventh, and tenth 

 Commandments ; in spite of which we dearly love the 

 miscreants. Moreover, cuckoos, being actively and 

 exclusively insectivorous, are of incalculable service to 

 all men who till the ground. A lady writes to me from 



1 Bidletin of the British Ornithologists' Club, March 1896. 



