ANIMAL BEHAVIOR — WALKER 291 



Particularly notable is the affection of the dog for man. This has 

 probably been the great factor in leading to the dog's domestication. 



Prairie dogs, which are not dogs at all but burrowing squirrels, are 

 sociable fellows that live in colonies and visit back and forth from 

 burrow to burrow. Indeed it is frequently difficult to ascertain T?ho 

 owns which burrow. I have observed, occasionally, if one prairie 

 dog is in a position heading partially into a burrow and is obstruct- 

 ing the way of another who wants to get in, the one behind will pinch 

 the tail of the traffic obstructor with his teeth. Apparently it is not 

 a very hard pinch but it seems invariably to get results. 



Recently I saw a young coypu or nutria, a large aquatic South 

 American rodent, sitting on a log projecting out into the water. An 

 adult was on the upper end of the log and wanted to go into the water. 

 It induced the young one to make way for it by reaching down and 

 gently but firmly pinching the young one's tail with its teeth. He also 

 obtained action. 



Among animals there are numerous instances of cooperation for 

 the common good. A well-known example is the beaver colony in 

 which several individuals cooperate in the building of the dam and 

 house, and the storing of the winter supply of wood for food. They 

 work together in perfect harmony and coordination. 



The banding together of the wild African hunting dogs {Lycaon 

 pictus)y of the coyotes, and wolves (Cmiis), and, occasionally, of a 

 few other animals that hunt prey too large to be taken by one individ- 

 ual, sometimes displays remarkable sagacity and cooperation. How- 

 ever, when the time for raising the young arrives, the packs usually 

 break up into pairs, each of which selects a den some distance from 

 the den of any others of its kind. Until the young are large enough 

 to join the pack, the adults forage from their dens for small animals 

 with which to feed their families. 



Pelicans {Pelecanus) apparently cooperate in their fishing. They 

 frequently swim on the surface of the water, several abreast and 

 just far enough apart so that no bird will grab for a fish that is 

 within the reach of another bird. When approaching a school of fish 

 in such formation, the birds have an advantage in that each one can 

 capture fish within its reach while the slowly advancing flock keeps 

 the school of fish continually in front of it. 



Those animals that live in groups probably all have some type of 

 government or leadership. It is easy to see that each herd of bison 

 is iiiled by a dictator, the strongest bull of the group. Flocks of 

 geese have a leader and give other evidences of government. The 

 disciplining of offenders can often be witnessed. Usually the ruler 

 of the herd or colony is also the sentinel who is on the lookout for 

 danger while others feed. But it is doubtful if this is always the 



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