126 The Black Bear 



have seen one stand up on his hind legs behind the 

 trunk of a good-sized tree and sidle round it, peeking 

 out as he went to watch a grizzly bear go by; and I 

 have already told how the two Black Bear took to 

 the trees when they heard a grizzly coming. I know 

 of nothing that better illustrates the keen senses of 

 these animals than the way in which they will detect 

 the approach of a grizzly long before a man's senses 

 can make him aware of the fact. In the Yellowstone 

 National Park, where there are many animals of both 

 species occupying the same ranges, I found that I could 

 always get warning of the approach of the grizzlies 

 when their twilight feeding time approached by the 

 sudden and complete disappearance of the Black Bear; 

 and on several occasions, in different parts of the 

 mountains, when the frequent flashes of our electric 

 cameras had scared the grizzlies away from that part 

 of the wood, the Black Bear seemed, strangely enough, 

 to be aware of the fact and made no attempt to retire 

 at their usual hour. This was so interesting an ex- 

 hibition of keen senses or quick intuition that I watched 

 very carefully during the whole period of my stay to 

 try to satisfy myself as to the source of their knowledge. 

 The fact that they began to be uneasy as the usual 

 hour for the grizzlies' arrival came near, sometimes led 

 me to think that they merely judged from past expe- 

 rience as to how long it was safe for them to stay out. 

 But, on the other hand, I saw so many cases where a 



