VOICES OF BIRDS. 
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ration, depression, or modulation, conveys intelligence 
equivalent to an uttered sentence. The voices of birds 
seem applicable, in most instances, to the immediate 
necessities of their condition ; such as the sexual call, 
the invitation to unite when dispersed, the moan of 
danger, the shriek of alarm, the notice of food. But 
there are other notes, the designs and motives of which 
are not so obvious. One sex only is gifted with the 
power of singing, for the purpose, as Buffon supposed, 
of cheering his mate during the period of incubation ; 
but this idea, gallant as it is, has such slight foundation 
in probability, that it needs no confutation ; and after 
all, perhaps, we must conclude, that, listened to, admired, 
and pleasing, as the voices of many birds are, either 
for their intrinsic melody, or from association, we are 
uncertain what they express, or the object of their 
song. The singing of most birds seems entirely a 
spontaneous effusion, produced by no exertion, or 
occasioning no lassitude in muscle, or relaxation of 
the parts of action. In certain seasons and weather, 
the nightingale sings all day, and most part of the 
night ; and we never observe that the powers of 
song are weaker, or that the notes become harsh and 
untunable, after all these hours of practice. The song 
thrush, in a mild moist April, will commence his tune 
early in the morning, pipe unceasingly through the 
day, yet, at the close of eve, when he retires to rest, 
there is no obvious decay of his musical powers, or any 
sensible effort required to continue his harmony to 
the last. Birds of one species sing in general very 
like each other, with different degrees of execu- 
tion. Some countries may produce finer songsters, but 
without great variation in the notes. In the thrush, 
however, it is remarkable, that there seems to be no 
regular notes, each individual piping a voluntary of his 
own. Their voices may always be distinguished amid 
the choristers of the copse; yet some one performer 
will more particularly engage attention by a peculiar 
modulation, or tune ; and should several stations of 
these birds be visited in the same morning, few or none 
