BIRD LIFE OF BARTICA 103 



The birds which lived in pairs and families were, for 

 the most part, well provided w r ith vocal organs, which they 

 used to good effect. Their songs and call-notes had, how- 

 ever, not so much penetrating quality, intended to cover 

 great distance, as characterized the voices of the solitary 

 ones. In almost none was there the sustained repetition or 

 rhythm found among the birds of the first category. Cha- 

 chalacas were an exception, but proving the rule, for they 

 were truly arboreal, and only by their adaptive ability had 

 they drifted from the jungle and taken instant advantage 

 of the secondgrowth. The chief point of interest in this 

 series was the distinction between the bird notes of the jun- 

 gle and those of the clearing. The indescribable vocal out- 

 bursts of guans and caracaras, the emotional expression 

 voiced by macaws, parrots and toucans need only to be men- 

 tioned. On the other hand ground doves, wrens, thrushes, 

 vireos, tanagers and orioles most of them representative 

 of temperate groups of birds filled the clearings with sweet 

 calls and sustained musical songs, reminiscent of northern 

 fields and woods and sharply contrasted with the more primi- 

 tive sounds produced by birds typical of the tropical jungles. 



The voice was little developed among birds living in 

 flocks, both smaller aggregations such as rails, anis, swallow 

 puff birds, swallows, finches, giant caciques and jays, and 

 those associated in large communities such as trumpeters, 

 swifts, smaller caciques, fork-tailed flycatchers and black- 

 birds. Notable exceptions were parrakeets which some- 

 times seemed to be all voice. The swallow puffbirds had 

 departed from the habits and mode of life of their jungle 

 relatives and usually lived in small colonies, and the fork- 

 tailed flycatchers, showing no unusual traits during the 

 nesting season, developed most remarkable gregarious habits 

 immediately afterwards, and during the molting season 

 roamed about the country in flocks of hundreds, roosting in 

 some specially selected spot, but during the day drifting 

 about wherever there was good hunting. A solitary trum- 



