136 ELEMENTARY ZOOLOGY. 



of the social life of the beavers. What opportunities does social 

 life offer for the care of the young? Find, by reference to texts, a 

 series of forms among the bees intermediate between the solitary 

 types and the social honey bees. How do the hornets pass through 

 the winter? 



152. Competition Among Animals of the Same Species. 



Animals of the same kind are not always in friendly 

 relations, however. They use the same kind of food, 

 and since thousands more are brought into life than can 

 possibly succeed, there must sometimes be a very vigor- 

 ous struggle among them for the food that is available 

 for the species. Sometimes animals live directly at the 

 expense of their own species. Young spiders are said 

 to devour one another before escaping from the cocoon, 

 which the mother has made for their protection. Many 

 fish are known to devour their own young. Large frogs 

 eat the small ones when other food is scarce. 



One of the most striking forms of the competition 

 between animals of the same sort is the struggle between 

 the males for the possession of the females. It may 

 take the form of actual combat, as in our barn-yard fowl 

 or among the members of the deer family. Adaptations 

 possessed by the males for this struggle are tusks, horns, 

 spurs, manes, and even great strength and size as com- 

 pared with the females. Of course these are not purely 

 for such combat, for the same qualities which would 

 make a male successful in his struggle with other males 

 would be of value in the defense of himself and his mate, 

 his young, and thus of the species, from their common 

 enemies. 



The competition between the males may be of a more 

 quiet kind. It is believed by many naturalists that 

 the striking colors, the song, the attractive behavior of 

 males may have some part in determining the choice of 



