422 'PICARIAN ' BIRDS 



Old World, and breeding in the temperate and sub-Arctic zones of 

 the northern hemisphere. In these respects it follows the practice of 

 a host of birds of various species and orders ; but, in common with 

 man)' foreign species of the group of which it is the t\-pical repre- 

 sentative, it possesses the strange and remarkable habit of depositing 

 its eggs, singly, in the nests of other kinds of birds. Arriving from 

 its African winter-quarters about the end of March or early in April, 

 the cuckoo spreads itself over almost the whole of Europe, passing 

 even well north of the Arctic Circle ; its advent being loudly proclaimed 

 by the well-known note, or " song," of the cock, which, in its typical 

 two-syllabled form — " cuk-ku " — is uttered chiefly during the breeding- 

 season, the cry later on being many-syllabled and irregular (the 

 "stuttering" of the cuckoo, as it is then called by country people). 

 Of the two sexes, cocks are by far the more numerous ; and it seems 

 that each hen associates with several males, who quarrel much among 

 themselves at the commencement of the breeding-season. In due 

 course the hen drops her eggs into the nests of other birds, placing 

 only one in each nest, and selecting more especially those of the pied 

 wagtail, titlark, reed-wren, and hedge-sparrow as nurseries. After the 

 egg is hatched, the young cuckoo, when only a few days old and still 

 blind and naked, proceeds to eject its foster-brothers (or such eggs as 

 may remain) by mounting them in turn in the hollow of its broad 

 back, and then scrambling backwards to the edge of the nest, over 

 which each is tilted, to perish miserably on the ground utterly neglected 

 by its own parents. The latter, on the other hand, devote themselves 

 entirely to the care of their voracious foster-child, who demands a 

 large supply of food, and displays a remarkable degree of stupidit)- 

 in the matter of receiving each morsel. By September the )-oung 

 cuckoo is full-fledged, and ready to follow its parents, most of whom 

 have crossed the Mediterranean by the middle of Jul}-. 



Before placing it in the nest, the female cuckoo generalh' lays her 

 egg on the ground, whence it is conveyed to its destination in her mouth. 

 So far as can be determined, it seems probable that individual cuckoos 

 place their eggs in the nests of one particular kind of birds, if such are 

 to be found ; so that we may have " wagtail-cuckoos " and " hedge- 

 sparrow-cuckoos." If this be so, the similarity in colouring often found 

 to exist between the egg of the cuckoo and the eggs among which it is 

 deposited is in some degree accounted for. It is noteworth\-, however, 

 that even when laid in hedge-sparrows' nests, cuckoos' eggs are very 

 seldom blue. How this parasitic habit arose is very difficult to 

 conjecture ; but it is important to observe that it is shared by a 



