4 
THE CUCKOO’S SECRET 
Thus it secures the undivided attentions of its 
fosterers, who continue to feed it for some time 
after it leaves the nest at about the age of three 
weeks. Adult Cuckoos cease to call and set about 
their southward migration when the females have 
finished laying their eggs ; that is, at the end of 
June and early in July. The young Cuckoos 
follow at a later date, thus providing one of the 
mysteries of migration, for their elders do not 
remain to lead the way. 
The above outline is introduced merely with 
the idea of forming a groundwork for the easier 
appreciation of the facts I am about to present, and 
also to show that even in such a meagre summary 
it is necessary at present to qualify statement after 
statement. 
Reference to the standard works on birds will 
show that hitherto knowledge of the Cuckoo has 
been in a state of flux. The proved facts about 
the bird have not bulked very largely, and we 
frequently find that complete theories are built 
upon some more or less isolated observation which 
may either have been wrongly interpreted or have 
been but the idiosyncrasy of some individual 
Cuckoo. With the invaluable assistance of my 
friends, we have together got so far to the heart of 
