102 TROPICAL WILD LIFE IN BRITISH "GUIANA 

 LARGE FLOCKS 



Trumpeters Swifts Fork-tailed Flycatchers 



Parrakeets Smaller Caciques Blackbirds 



This association of grades of social instinct had many 

 more points of interest than the mere statistical appearance 

 would indicate. I shall discuss one only, that of voice, which 

 had a close bearing upon the relative gregariousness. 



Of the twenty-two groups with solitary habits, seven 

 were decidedly inhabitants of open country, where they could 

 readily see one another, and in these the voice was more or 

 less negligible. Two out of the seven, vultures and snake- 

 birds, lacked it altogether, while the Guiana representatives 

 of terns, waders, herons, hawks and kingfishers seldom made 

 themselves heard. Hummingbirds, while usually silent, had 

 considerable vocal possibilities for their size, but their mar- 

 velous power of flight doubtless usurped many of the ne- 

 cessities of loud intercommunication. Of the fourteen re- 

 maining groups all were inhabitants of dense jungle and 

 without exception possessed of remarkable vocal powers. 

 These had an interesting generic resemblance in that the 

 tones of the songs or calls were uniformly loud and, in the 

 majority of cases staccato, or with an insistent rhythm. To 

 anyone familiar with these birds in life it is sufficient to men- 

 tion tinamou, jungle pigeons, owls, goatsuckers, trogons, 

 motmots, cuckoos, barbets, jacamars, puff birds, goldbirds, 

 cotingas and woodhewers, to recall memories that first are 

 aural and then optical. To this the quadrille-bird must be 

 added, a wren whose jungle life and solitary habits have 

 divorced it from the rest of its diminutive fellows, and lent 

 to its voice the startling staccato quality so characteristic of 

 jungle birds, without depriving it of any of the sweetness 

 which characterizes the songs of other wrens. It is worthy 

 of note that the members of three of these groups were 

 nocturnal, the cause of reduction of visual communication 

 here being astronomical, not vegetative! 



