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 flocks and fly high 
and far, calling loudly as they go; the bobolinks straggle 
away one at a time, flying mostly inthe 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. tn the little brooks in spring 
male minnows can be found with warts on the nose or head, 
