CROSSING THE BOLIVIAN HIGHLANDS 293 



season streams rise with startling rapidity, and parties 

 have often been forced to camp on the river-bank many- 

 days until the water went down. To tmii back is hope- 

 less, as the last stream crossed is just as high as the one 

 ahead; there is nothing to be done but wait. 



Wild animals are particularly abundant in this section 

 of the country. All day long we could hear the raucous 

 scream of long-tailed, multicolored macaws (Ara) as they 

 flew two by two overhead. Many hawks sat alertly on 

 dead snags near the water, and black-and-white gulls flapped 

 hurriedly up and down along the river. Occasionally we 

 caught a glimpse of a smaU flock of muscovies, the largest 

 of South American ducks, as the great, black birds flew 

 heavily up-stream. There were also black guans, resem- 

 bling small turkeys, which sat quietly in the tops of tall 

 trees tmtil we approached quite near to them; then, emit- 

 ting a loud, mule-like bray, they set their wings and soared 

 across the river or down into the underbrush. At night the 

 forest was usually quiet, reminding one of "Pools of Si- 

 lence." Occasionally, however, the still air was suddenly 

 rent by the most xmearthly noise that mortal man ever 

 heard, and the woods rang with the wild, insane cackle of 

 forest-rails (Aramides). Beginning with a shrill oohoo-hee- 

 cra, the demoniacal chorus continued several minutes with- 

 out interruption, swelling constantly and finally ending 

 with a few low, explosive cow-cow-cows. A nimiber of 

 birds always sang together, and the first time one hears the 

 performance it is enough to make the flesh creep and the 

 hair to stand on end; but even after becoming somewhat 

 accustomed to the noise, it falls short of conducing to peace- 

 ful slumber, suggesting as it does the agonized shrieks of 

 some tortured spirit of the jungle. 



Night-monkeys (DouroucouU) were apparently plentiful, 

 but we never saw them in the daytime. After darkness 

 had fallen they began to move about in the tree-tops; one 

 night a troop selected the tree under which we camped for 

 the scene of their frolic, and kept us awake the greater 



