248 ANIMAL LIFE 



their superfluous energy the more they will talk. Much of 

 the singing of birds, and the crying, calling, and howling of 

 other animals, are mere play, although singing primarily be- 

 longs to the period of reproduction, and other calls and 

 cries result from social instincts or from the instinct to 

 care for the young. 



134. Climate. Climatic instincts are those which arise 

 from the change of seasons. When the winter comes the 

 fur-seal takes its long swim to the southward; the wild 

 geese range themselves in wedge-shaped nocks and fly high 

 and far, calling loudly as they go ; the bobolinks straggle 

 away one at a time, flying mostly in the night, and most of 

 the smaller birds in cold countries move away toward the 

 tropics. All these movements spring from the migratory 

 instinct. Another climatic instinct leads the bear to hide 

 in a cave or hollow tree, where he sleeps or hibernates till 

 spring. In some cases the climatic instinct merges in the 

 homing instinct and the instinct of reproduction. When 

 the birds move north in the spring they sing, mate, and 

 build their nests. The fur-seal goes home to rear its young. 

 The bear exchanges its bed for its lair, and its first business 

 after waking is to make ready to rear its young. 



135. Environment. Environmental instincts concern 

 the creature's mode of life. Such are the burrowing instincts 

 of certain rodents, the woodchucks, gophers, and the like. 

 To enumerate the chief phases of such instincts would be 

 difficult, for as all animals are related to their environ- 

 ment, this relation must show itself in characteristic in- 

 stincts. 



136. Courtship. The instincts of courtship relate chiefly 

 to the male, the female being more or less passive. Among 

 many fishes the male struts before the female, spreading 

 his fins, intensifying his pigmented colors through muscu- 

 lar tension, and in such fashion as he can makes himself the 

 preferred of the female. In the little brooks in spring 

 male minnows can be found with warts on the nose or head, 



