158 BRITISH BIRDS. [vol. xin. 



may be given by a single bird, but it is much more often 

 heard as a duet. The duet is remarkable in being accurately 

 timed ; the notes of one bird alternate with those of the other, 

 so as to produce the effect of an echo. Sometimes there is a 

 difference in quality as well as in time, the phrase being given 

 in a hooting tone by one bird and by the other as a peal of 

 demoniac laughter. The effect of this is very weird. This 

 duet may be said to be better organised than that of the 

 Dabchick. 



So far not much attention has been paid to this subject, 

 but I have no doubt that observation will bring to light 

 many new examples of duets in birds. 



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