448 Observations on the Cuckoo. 
May: a fortnight is taken up by the ‘sitting 
bird in hatching the egg: the young bird 
generally continues three weeks in the nest 
' before it flies: and the foster parents feed it 
more than five weeks after this period; so 
that, if a cuckoo should be ready with an 
egg much. sooner than the time pointed out, 
not a single nestling, even of the earliest, 
would be fit to provide for itself, before its 
parent would be instinctively directed to 
seek a new residence, and would be thus 
compelled to abandon its young one; for old 
cuckoos take their final leave of this country 
in the first week of July. 
If nature had allowed the cuckoo to stay 
here as long as some other migratory birds, 
which produce a single set of young ones, 
(as the swift or nightingale, for example) 
and had allowed it to rear as large a number 
as any bird is capable of bringing up at one 
time, these might not have been sufficient to 
answer her purpose; but by sending the 
cuckoo from one nest to another, it is reduced 
to the same state as the bird whose nest is 
daily robbed of an egg, in which case the 
stimulus for incubation is suspended. Of this 
we havea familiar example in the common 
domestic fowl. That the-cuckoo actually lays 
a great number of eggs, dissection seems to 
