OBSERVATIONS ON THE CUCKOO. 57 
foster-parent, as it is the same whether it be reared 
by the Hedge-Warbler or by any other bird. It 
never acquires the adult note during its stay in this 
country. 
The growth of the young Cuckoo is very rapid ; 
and as it is fed for a long period by the small birds 
which have the care of it, they frequently have to 
perch on its back or half-expanded wing, in order 
to gain a sufficient elevation to put the food into its 
mouth. 
There seems to be no precise time fixed for the 
departure of young Cuckoos. Probably they go off 
in succession as soon as they are capable of taking 
care of themselves ; for though they stay here till they 
become nearly equal in size and growth of plumage 
to old ones, yet in this very state the care of their 
foster-parents is not withdrawn from them. If they 
did not go off in succession, it is probable that we 
should see them ih large numbers by the middle of 
August; for as they are to be found in great plenty 
when in a nestling state, they must then appear 
very numerous, since all of them must have quitted 
the nest before that time; but this is not the case, 
for they are not more numerous at any season than 
the parent birds are in the months of May and 
June. 
Such are the most important particulars which have 
resulted from Dr. Jenner’s well-conducted inquiry ; 
and to the accuracy of the greater part of them I 
