202 
THE CUCKOO’S SECRET 
to show no trace of the Cuckoo’s visit. However, 
any one studying the Cuckoo by my system should 
have little difficulty in discovering her way with 
the Reed Warbler. I shall expect it to be found 
that she lays on or over the nest. 
In 1897 the Field published a record of a Cuckoo 
having been seen to sit on and lay her egg in the 
nest of a Pied Wagtail. 
Probably most practical ornithologists have 
noticed that nests in certain spots are victimised 
by Cuckoos season after season. This of course 
is because the nests are built within good view of 
favourite Cuckoo observation-posts ; and it may 
be a pair of foster-birds which the same Cuckoo has 
victimised in previous seasons. A patient watch 
kept on such a nest as soon as the owner has laid 
an egg would no doubt result in the observer seeing 
a Cuckoo in the act of egg-deposition ; but unless 
my method is employed one cannot tell on which 
out of four or five days the Cuckoo will lay in that 
nest, if lay she does. 
Since the individuals of at least most species 
vary enormously in temperament, a fact well 
known to all bird-photographers, it is reasonable 
to assume that the behaviour of fosterers of other 
species customarily victimised by Cuckoos runs 
