224 
THE CUCKOO’S SECRET 
explanation that they were the eggs of two different 
Cuckoos, possibly related. On the other hand, such 
a high degree of variation exists amongst Cuckoos’ 
eggs, that the odds are heavily against two Cuckoos 
laying, in the same area and in the same season, 
eggs which cannot be distinguished with ease. 
For my part, I am confident, on the strength of 
the close observations recorded in this book — and 
I trust they will convey to my readers the same 
degree of confidence — that the several “ clutches ” 
of Cuckoos’ eggs which I now possess were each 
laid by a separate individual hen Cuckoo, in many 
instances actually under my own eyes. 
Cuckoo’s Preference in Selection of Fosterer 
The next conclusion which I consider is amply 
substantiated by the recent observations of other 
practical students of the Cuckoo, as well as by my 
own, is that a dominant hen Cuckoo always selects for 
preference the same species of fosterer as the recipient 
of her eggs. I say “ for preference ” because in 
my experience this rule is only broken when the 
Cuckoo, on one of her laying-days, is unable to 
find within her territory suitable accommodation 
in the nest of her regular fosterers. 
