The Crested Sc7'eamer, 
227 
spontaneous outbursts of a melody so powerful from 
one of these large flocks, and though accustomed 
to hear these birds from childhood, I have often 
been astonished at some new effect produced by a 
large multitude singing under certain conditions. 
Travelling alone one summer day, I came at noon 
to a lake on the pampas called Kakel — a sheet 
of water narrow enough for one to see across. 
Ohakars in countless numbers were gathered along 
its shores, but they were all ranged in well-defined 
flocks, averaging about five hundred birds in each 
flock. These flocks seemed to extend all round 
the lake, aod had probably been driven by the 
drought from all the plains around to this spot. 
Presently one flock near me began singing, and 
continued their powerful chant for three or four 
minutes ; when they ceased the next flock took up 
the strains, and after it the next, and so on until 
the notes of the flocks on the opposite shore came 
floating strong and clear across the water — then 
passed away, growing fainter and fainter, until 
once more the sound approached me travelling 
round to my side again. The effect was very 
curious, and I was astonished at the orderly way 
wuth which each flock waited its turn to sing, 
instead of a general outburst taking place after the 
first flock had given the signal. On another occa- 
sion I was still more impressed, for here the largest 
number of birds I have ever found congregated at 
one place all sung together. This was on the 
southern pampas, at a place called Gualicho, where 
I had ridden for an hour before sunset over a 
marshy plain where there was still much standing 
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