HISTORY AND NATURAL HISTORY 37 



are estimated to hibernate in these caves by the 

 milHons; and they may be found through the day 

 in sleeping masses a yard across, hanging from the 

 roof like a swarm of bees. 



Even larger mammals may collect into great, 

 closely packed herds. The migrating caribou on 

 the tundra are said to pour south in hordes that 

 flow past a given point for hours or even for days. 

 And of the antelope on the plains of Mongolia, (17) 

 Roy Chapman Andrews says that he has seen thou- 

 sands upon thousands of bucks, does, and fawns 

 pour over the rim and spread out on the plain. 

 Sometimes a thousand, more or less, would dash 

 away from the fierd, only to stop abruptly and feed. 

 The mass of antelope were in constant motion even 

 when the animals were undisturbed. They scattered 

 before his automobile only to re-form within a few 

 hours. In that region only the grassland antelope 

 gathers in such immense herds; the long-tailed 

 desert species never does so, probably because there 

 is not enough food to support them in their more 

 arid dwelling place. 



These are merely a few of the more dramatic 

 instances of the collection of great masses of animals 

 in a small space. They are more spectacular but 

 probably less important than are the innumerable 

 smaller aggregations of animals which are frequently 



