THE CUCKOO. 
79 
depression or hollow, between its shoulders, into 
which, by an odd sort of jerk, it contrives to lift 
the young birds, and then shuffling backwards to the 
edge of the nest, throws them over. This hollow, 
however, only remains for a certain time, and then 
fills up ; and it is an extraordinary fact, that if the 
young birds are designedly kept in the nest till the 
hollow is filled up, the young Cuckoo, as if aware 
that it has no longer the power to get rid of them, 
allows them to remain unmolested. 
