156 BIRDS OF LA PLATA 
before it has time to sprout@##While watching crowds 
of these birds feeding on the ground, I noticed that 
their manner was in striking contrast to that of the 
C. picazuro, which has slow and dignified motions ; 
for it hurried about, and snatched up its food with 
such rapidity that the most animated motions of 
other birds that feed in flocks on the ground seemed 
languid in comparison. This excessively lively habit 
is, no doubt, directly caused by the conditions of 
life; the sterile soil and scanty vegetation of the 
region it inhabits require in a species going in large 
bodies, and subsisting exclusively on fallen seed, a 
greater activity than is necessary in the rich fertile 
region further north. 
Its song is composed of notes equal in length and 
number to that of the Picazuro, but its voice is 
always hoarse, like that of the European Wood- 
Pigeon, when his early spring song has a low, throaty 
sound, as if the bird was still suffering from the 
effects of a winter cold. 
The great body of these birds retire on the ap- 
proach of summer from the Rio Negro valley, a few 
only remaining to breed. Their nesting-habits and 
eggs are like those of the Picazuro. 
