THE LAYING OF CUCKOOS 181 
that it would be almost impossible in any given 
and comparatively limited area for the breeding 
period of any one species to be so spread out, 
unless arranged artificially, as in the case of my 
particular studies, as to provide at least one new 
nest of that species, containing one or more 
fresh eggs, on every alternate day throughout a 
period of, say, six weeks from about mid-May 
onwards. 
Reference to the record of the domestic economy 
of each pair of Meadow Pipits on my common in 
1920 will show that the reduction of pairs from 
nine to four, attributed to a Kestrel searching for 
food for her newly-hatched young, began to make 
itself seriously felt about June 4-6. Until this 
time the Cuckoo always had more than a sufficiency 
of fosterer’s nests available. 
According to my theory, that reduction of 
accommodation would tend to check the laying of 
the Cuckoo about a week later. Hence the break 
after the laying of her sixteenth egg on June 12, 
1920. But for the constant and rapid restarting of 
new nests of those fosterers left after the depreda- 
tions of the Kestrel, it is more than probable that 
this Cuckoo would not have resumed laying after 
the deposition of her series of sixteen. 
