228 
THE CUCKOO’S SECRET 
normally have laid (i.e. one after the sixteenth egg 
in 1920, another after the fifth, and the third after 
the tenth eggs in 1921), but on which we did not 
see her lay and therefore did not know whether 
she laid or not. My answer is that I regarded it 
as a most valuable point to endeavour to establish 
whether she had laid or not, because if we could 
show that she did not lay, it would naturally lead 
to the inquiry why did she not lay. 
On each of the three “ laying-days ” just 
mentioned there was suitable accommodation within 
her territory : in other words, there was, on the 
common where she laid all her sixty-one eggs, a nest 
(hitherto unused) of her natural fosterers containing 
one or more Meadow Pipit’s eggs, unincubated, 
and therefore available. Why, then, did she not 
lay on these days ? I contend that the explanation 
lies in the fact that a few days prior to each of the 
“ laying-days ” the Cuckoo foresaw a threatened 
insufficiency of prospective foster birds’ nests, and 
that this anticipated shortage of accommodation 
inhibited her laying. Owing to our system of 
continually stimulating the rebuilding by her 
natural foster birds, she soon resumed her normal 
regularity of laying. 
Particularly significant, in this connection, is 
