316 Observations on the 
gesticulations; and are altogether different 
from their ordinary songs, which seem to be 
occasioned by an exuberance of animal spi- 
rits, arising from anabundance of nourishing 
food, and an increase of temperature, and by 
a spirit of emulation and rivalry among the 
males. In confirmation of what is here ad- 
vanced, I shall observe, that I have known 
many instances of birds having nests after they 
have entirely ceased singing ; and that some 
species, as the woodlark, redbreast, and wren, 
sing long after they have done breeding : ca- 
ged birds also continue in song much longer 
than birds at large, though they have no mates 
to solace and amuse; and it is remarkable, 
that almost any kind of continued noise is 
sufficient to stimulate them to sing. That 
birds of the same species distinguish each 
other by their notes, better than by any other 
circumstance, and that the songs of the 
males serve to direct the females where to 
seek their society, as Montagu has suggested, 
appears to me highly probable; but I must 
differ from this ingenious writer, when he as- 
serts, that love is the sole cause of their 
songs.* In support of this opinion he states, 
that the males of our warblers, before they 
* This he does, in effect, in the introduction to his Ornithological 
Dictionary, p. 28, and following. 
