376 OUR SEARCH FOR A WILDERNESS. 



The three commonest dragon-flies were Diastatops tincta, 

 Erylhrodiplax umbrata and E. peruviana. 



There were two pairs of Black-capped Mocking-thrushes ™ 

 on the island and they afforded us much amusement. They 

 are true cousins of the Catbird and Mockingbird, and from 

 their actions would almost seem to have a strain of Chat blood! 

 A pair lived in each of the brush clumps a and h (Fig. 147) and 

 hour after hour would sit calling and answering each other. 

 One pair (the two birds sitting close to each other) would 

 shout in unison powie! powie! powie! rapidly a dozen times 

 in succession. The other pair responded week! iveek! week! 

 week! as often and as rapidly. At each enunciation the 

 half-spread tails of the respective pair of birds wagged vio- 

 lently from side to side, exactly as if pulled with a string. 

 As the utterances of each of the two birds were synchron- 

 ous, the wagging was always in perfect time, but sometimes 

 the "strings" got crossed with this effect (a); or this (b) ; 



but almost every time the movement was in unison thus 

 (c); or thus (d). These active, interesting birds have in 

 addition an elaborate song, uttered singlv, which these 

 individuals were practising but which we had heard fully 

 developed at La Brea in Venezuela. 



