98 THE PLAY OF ANIMALS. 



son relates of the crested screamer, or chakar (Chauna 

 cliavarria), that has a very loud voice: '" There is some- 

 thing strangely impressive in these spontaneous out- 

 bursts 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 cer- 

 tain 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. 

 Chakars in countless numbers were gathered along its 

 shores, but they were all arranged in well-defined 

 flocks, averaging about five hundred birds in each flock. 

 These flocks seemed to extend all round the lake, and 

 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 of 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 as- 

 tonished at the orderly way with which each flock 

 waited its turn to sing, instead of a general outburst 

 taking place after the flrst flock had given the signal. 

 On another occasion I was still more impressed, for here 

 the largest number of birds I have ever found congre- 

 gated at one place sang all 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 water in the 

 rushy pools, though it was at the height of the dry 



