74 OBSERVATIONS ON THE CUCKOO. 
must, therefore, be perfectly innate. It may be re- 
marked also, that the chirp of young Cuckoos is the 
same, as Dr. Jenner rightly observes, whatever the 
species of their foster-parents may be; hence it fol- 
lows 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 Titlarks is not entirely discontinued 
till towards the middle of August, when, having ob- 
tained a considerable command of wing, a desire to 
migrate prompts it to leave the country. The in- 
stinctiveness of this impulse one would be inclined to 
believe could not admit of a doubt ; for Titlarks are 
not birds of passage, and as old Cuckoos depart late 
in June or early in July, it is clear that young ones 
cannot derive any benefit from their experience ; yet 
Darwin maintains that migration among birds is as 
much an acquired art as navigation is among men. 
With regard to the Cuckoo, I trust that I have 
said sufficient to convince every impartial inquirer 
that it is actuated in this particular purely by in- 
stinct ; and, reasoning from analogy, I should be led 
to conclude that this is the case with all Migratory 
Birds without exception. But to return to the 
Cuckoo. Early in the ensuing spring it revisits the 
country where it was bred, or seeks another equally 
well suited to its habits and necessities. If a male 
bird, its well-known cry, which is now heard for the 
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