LARKS, WOODPECKERS, ETC. 193 
alone, however, do not constitute the whole of its 
diet, for insects of almost every kind fall victims to its 
appetite ; and as that appetite is by no means small, 
and as the bird satisfies it by no illicit means, we 
must look upon the cuckoo as essentially a beneficial 
bird, and one which should be protected and encou- 
raged by every means in our power. 
The most interesting feature, of course, in the life- 
history of the cuckoo is its invariable habit of laying 
its eggs in the nest of another bird, generally that of 
the hedge-sparrow. It is by no means particular, 
however, as to the character of the foster-parents 
which it selects, and is almost as partial to the nest 
of the pied wagtail or the meadow pipit as to that of 
the bird already named, while quite a long list might 
be drawn up of the various birds which are occasion- 
ally entrusted with the doubtful honour of rearing a 
young cuckoo. It seems very probable that the 
selection is made, in some degree, in accordance with 
the colour of the egg, which varies considerably, and 
often harmonises strangely with those of the legiti- 
mate owner of the nest in which it is placed. At a 
recent conversasione of the Croydon Microscopical 
and Natural History Society, a most interesting exhibit 
was made of a large number of cuckoos’ eggs, each 
accompanied by an egg or two from the nest from 
which it was taken. In the majority of cases there 
was more or less resemblance between the eggs of the 
two birds, and in one very singular instance a cuckoo’s 
egg, taken from the nest of a wheatear, was of a pale 
blue colour, with only faint traces of the ordinary 
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