WINGED VOYAGERS. 17 
human kinsmen, learn by experience and tutelage, 
and are also gifted with a sure instinct that amounts 
in many cases almost to reason. Take, for instance, 
this one fact. As the sun creeps northward in the 
spring, it pours a more and more intense heat upon 
the northern portions of the tropical and sub-tropical 
regions. The heat would soon become intolerable 
to certain birds, which have doubtless tried the 
experiment of spending the summer in equatorial 
countries; or if individuals now living have not 
tried it, perhaps some of their more or less remote 
ancestors have. That birds do make experiments 
is proved by the fact that several pets of mine 
will carefully “sample” a new kind of food offered 
them, and if they do not find it to their taste, 
will let it severely alone; nor is it any the less 
evident that young birds receive instruction from 
their elders. Thus the necessity of leaving the 
torrid regions as summer approaches may have 
been impressed on the migrating species from time 
immemorial. 
Again, as spring advances, insect and vegetable 
life is revived in regions farther north, and this 
certainly must act as a magnet upon the birds, 
drawing them from point to point as the supply of 
food becomes scarce in the more southern localities. 
Then, let us suppose for a moment that all the birds 
did remain in the south through the summer ; there 
would sooner or later be a bird famine in the land, 
for the supply of seeds and insects would soon be 
exhausted. Our feathered folk are simply obliged, 
