226 The Naturalist in La Plata. 
the other notes of the female being long powerful 
notes with a trill in them; but over them sounds 
the clear piercing voice of the male, ringing forth 
at the close with great strength and purity. The 
song produces the effect of harmony, but, comparing 
it with human singing, it is less like a duo than a 
terzetto composed of bass, contralto, and soprano. 
At certain times, in districts favourable to them, 
the chakars often assemble in immense _ flocks, 
thousands of individuals being sometimes seen con- 
eregated together, and in these gatherings the birds 
frequently all sing in concert. They invariably— 
though without rising—sing at intervals during the 
night, “counting the hours,” as the gauchos say ; 
the first song being at about nine o’clock, the 
second at midnight, and the third just before dawn, 
but the hours vary in different districts. 
I was once travelling with a party of gauchos 
when, about midnight, it being intensely dark, a 
couple of chakars broke out singing right ahead of 
us, thus letting us know that we were approaching 
a watercourse, where we intended refreshing our 
horses. We found it nearly dry, and when we 
rode down to the rill of water meandering over the 
broad dry bed of the river, a flock of about a thou- 
sand chakars set up a perfect roar of alarm notes, 
all screaming together, with intervals of silence 
after; then they rose up with a mighty rush of 
wings. They settled down again a few hundred 
yards off, and all together burst forth im one of 
their grand midnight songs, making the plains echo 
for miles around. 
There is something strangely impressive in these 
