CHAPTER XV 
THE YOUNG CUCKOO 
The generally accepted incubation period for the 
egg of the Cuckoo is twelve to thirteen days, and 
that is quite easy of proof. In at least many 
instances it may be even shorter than twelve days, 
for there is no doubt that many species of small 
birds can and do at times hatch their eggs in 
shorter periods than those usually given by the 
authorities, and in normal circumstances we find 
that, more often than not, the Cuckoo’s egg is the 
first to hatch. By normal circumstances, I mean 
those in which the egg of the parasite starts on equal 
terms with the eggs of the dupe. 
There has always been a speculation as to how 
the Cuckoo nearly always contrives to deposit her 
egg in nests in which incubation has not commenced. 
One theory was that she hesitated to drive a sitting 
bird off her eggs ; and quite an ingenious idea was 
that the Cuckoo took away one egg to test its 
condition. What really happens is of course 
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