CUCKOOS. 



273 



The reason of this strange proceeding seems to be that the 

 cuckoos produce their eggs only at intervals of several days, and 

 as their residence in temperate climates is but short, the young 

 could hardly be brought to maturity by their own parents in time 

 to take their departure with them. The &g^ of the cuckoo is of 

 very small size in comparison with the bird ; its weight does not 

 exceed that of a skylark's egg, although the comparative size of 

 the two birds is as four to one. Hence the egg of the parasite is 

 readily introduced into the nest of its intended foster-parent, and 

 the latter is not alarmed, as it might be, by the presence of an Q%g 





^**^ 



Fig. 141.— The Common Cuckoo {Cuciilus canonn). 



so large as to be positively inconvenient. This is of some conse- 

 quence, as the birds whose nests are selected by the cuckoo for the 

 reception of its eggs are all much less than itself The cuckoo's, 

 egg is hatched in a shorter period than those of its foster-parent, 

 and thus the young cuckoo commonly makes its appearance before 

 many of the eggs of the latter are hatched ; moreover, as it has to 

 grow rapidly, it requires to be supplied with a much larger quan- 

 tity of food than would fall to its share if the insects and worms 

 collected by the old birds had to be divided among a nestful of 

 hungry claimants. With this exceedingly selfish object in view, 



18 



