THE CUCKOO’S SECRET 
192 
estimate the number of eggs laid by a Cuckoo in a 
season. Whilst, as I have shown, a Cuckoo can 
and will lay up to twenty-one eggs, yet she is not 
likely to do so under normal circumstances. The 
opportunities to do so are very seldom existent, 
and the earlier ornithologists, who placed the 
Cuckoo’s average clutch at four to six eggs, were 
almost certainly far nearer the truth than the later 
observers, who, in basing their calculations upon 
the large series obtained by systematic endeavour, 
completely overlook the very important fact that 
they have themselves, by taking the Cuckoo’s eggs 
as laid, together with those of the fosterers, provided 
her with a stimulus conducive to her further 
laying. 
Additional evidence of dominating Cuckoos will 
be found on referring back to Chapters IX and X. 
