470 Observations on the Cuckoo. 
geny, it isg@Wdent that it cannot be acquired 
from them; it must, therefore, be perfectly 
innate. It may be remarked also, that the 
chirp of young cuckoos is the same, as Mr. 
Jenner rightly observes, whatever the species 
interest ghee no further about their pro- 
of their foster parents may be: hence it follows 
that it is not learned from any other bird, but 
is exclusively their own. After remaining in 
the nest about three weeks, this young bird 
deserts it early in July, and begins to acquire 
the use of its wings; but the care of the tit- 
larks is not entirely discontinued till towards 
the middle of August; when having obtained 
a considerable command of wing, a propensity 
to migrate prompts it to leave the country. 
The instinctiveness of this propensity one. 
would be inclined to believe could not admit 
of a doubt; for titlarks are not birds of pas- 
sage, and as old cuckoos depart late in June, 
or early in July, it is clear that young ones 
cannot derive any benefit from their experi- 
ence: yet Darwin maintains, that migration, 
among birds is as much an acquired art as 
navigation is among men. With regard to 
the cuckoo, 1 trust that I have said sufficient. 
to convince every impartial inquirer, that it 
is actuated in this particular purely by instinet; 
and, reasoning from analogy, I should beled 
