CUCKOOS. 



877 



BO that cuckoos' eggs are often supposed to bo double-yolked eggs of the same species. 

 This fact lias given rise to the extravagant theory that the cuckoo jiosscsses the power 

 of determining the color of her eggs, so as to make tliem resemble the other eggs in 

 the nest. The explanation, probably, is that the eggs of each individu.al cuckoo vary 

 very slightly. A cuckoo which lays blue eggs always lays blue eggs, and its descend- 

 ants will continue to lay blue eggs ; it was probably hatched in a nest containing blue 

 eggs, and will, to the best of its ability, intrust the care of its eggs to foster-parents of 

 the same species as those which tended it in its infancy." 



Tlic cuckoo feeds on insects, especially caterpillars, being particularly fond of the 

 large hairy ones which most other birds despise, and the walls of the stomach are 



Fio. 180. — Coccystes glatularius, great spotted cuckoo. 



often found lined with the matted hairs of these larva'. It is also fond of hairy 

 bumble-bees, but a most extraordinary diet for a cuckoo is certaiidy the small crusta- 

 ceans (Gammarida?) which aboimd on sandy bcaciies; still, the present writer was 

 fortunate enough, during a .short stay on Cojuier Island, near Kamtschatka, to shoot 

 a cuckoo which had the stomach crammed with these animals. In justice to the l)iril, 

 it must be stated, however, that the island had neither hairy caterpillars nor bumlile- 

 bees to offer. 



Another European species, the great spotted cuckoo (Cocn/ifk's f/hiiKfariiin), of 

 which we also jiresent a cut, is confined to the nortlicrn and eastern ])arts. Its 

 breeding habits are likewise parasitic, though somewhat different, as it usually deposits 



