254 The Naturalist in La Plata. 



formed daily, the birds beginning to assemble at 

 about nine or ten o'clock in the morning, their 

 number increasing through the day until it reaches 

 its maximum between two and four o'clock in the 

 afternoon, after which it begins to diminish, each 

 bird going off to its customary shelter or dwelling- 

 place. Mr. Bates, who first described these wander- 

 ing bands, says that he could always find the 

 particular band belonging to a district any day he 

 wished, for when he failed to meet with it in one 

 part of the forest he would try other paths, until he 

 eventually found it. The great Amazonian forests, 

 he tells us, appear strangely silent and devoid of 

 bird life, and it is possible to ramble about for 

 whole days without seeing or hearing birds. But 

 now and then the surrounding trees and bushes 

 appear suddenly swarming with them. " The bust- 

 ling crowd loses no time, and, always moving in 

 concert, each bird is occupied on its own account 

 in searching bark, or leaf, or twig. In a few 

 moments the host is gone, and the forest path 

 remains deserted and silent as before." Stolzmann, 

 who observed them in Peru, says that the sound 

 caused by the busy crowd searching through the 

 foliage, and the falling of dead leaves and twigs, 

 resembles that produced by a shower of rain. The 

 Indians of the Amazons, Mr. Bates writes, have a 

 curious belief to explain these bird armies ; they 

 say that the Papa-uira, supposed to be a small grey 

 bird, fascinates all the others, and leads them on a 

 weary perpetual dance through the forest. It seems 

 very wonderful that birds, at other times solitary, 

 should thus combine daily in large numbers, includ- 



