286 The Naturalist in La Plata. 
habitually expressed, although not infrequently 
with variations due to the greater intensity of the 
feeling. In some migrants the males arrive before 
the females, and no sooner have they recovered 
from the effects of their journey than they burst 
out into rapturous singing; these are not love-strains, 
since the females have not yet arrived, and pairing- 
time is perhaps a month distant; their singing 
merely expresses their overflowing gladness. The 
forest at that season is vocal, not only with the 
fine melody of the true songsters, but with hoarse 
cawings, piercing cries, shrill duets, noisy choruses, 
drummings, boomings, trills, wood-tappimgs—every 
sound with which different species express the glad 
impulse; and birds like the parrot that only exert 
their powerful voices in screamings—because “‘ they 
can do no other’”—then scream their loudest. 
When courtship begins it has in many cases the 
effect of increasing the beauty of the performance, 
giving added sweetness, verve, and brilliance to the 
song, and freedom and grace to the gestures and 
motions. But, as I have said, there are exceptions. 
Thus, some birds that are good melodists at other 
times sing in a feeble, disjointed manner during 
courtship. In Patagonia I found that several of 
the birds with good voices—one a mocking bird— 
were, like the robin at home, autumn and winter 
songsters. 
The argument has been stated very briefly: but 
little would be gained by the mere multiplication of 
instances, since, however many, they would be 
selected instances—from a single district, it 1s true, 
while those in the Descent of Man were brought 

