INTRODUCTORY 
3 
the males precede the females. To the unpractised 
eye the sexes are indistinguishable in appear- 
ance. The male is most easily identified by his 
note of “ cuck-oo,” the female by an equally un- 
mistakable, though not nearly so well-known, 
“ bubbling ” call of a single syllable repeated 
several times quickly and sharply. In at least 
many instances both males and females return to 
the haunts occupied in previous seasons. The 
authorities state that the bird is polyandrous, but I 
think we have insufficient evidence as yet on which 
to lay down the law. # The eggs are always deposited 
singly in the nests of other species, such as pipits, 
warblers, wagtails, etc., the fosterer hatching the 
egg and rearing the young. Each hen Cuckoo is 
probably parasitic, so far as she can be, upon a 
particular species, her dupes being most likely 
selected from amongst that species by which she 
herself was reared. The number of eggs laid in a 
season by a Cuckoo in normal circumstances is not, 
one might almost say cannot be, ascertained ; on 
the average it may be anything from six to a dozen. 
When hatched, the young Cuckoo almost imme- 
diately sets to work to evict the hatched or un- 
hatched contents of the nest in which it finds itself. 
* See Chapter XVII., p. 235. 
