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-tappings 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 is true, 

 while those in the Descent of Man were brought 



