CHAPTER XXVIT 
HOW AND WHY DO BIRDS TRAVEL ? 
Wutte birds appear so free and roving, they usu- 
ally have rather definite homes or home regions, re- 
maining in these their entire lives if not forced away ; 
and many use the same tree or other location from 
year to year to nest in. It is certain that where a 
bird rears its young is its home, and this is surely the 
home and native place of the nestling. 
But stress of cold and scarcity of food may, and 
often does cause the birds to travel, and they take 
their well-known journeys southward at the approach 
of the winter. Such as live on fiying insects are com- 
pelled to go. 
But all the birds do not travel. Some stay in the 
same region the year around, enduring the cold and 
picking up a living in spite of the departure of the 
insect and the berry. Why, then, do others leave us ? 
It would seem that they, too, might learn the art of 
living in and enduring the severities of the winter, 
and save themselves the great labor and danger of a 
long journey which is so often fatal to many. 
It is one of the theories of the migration of birds 
north of the equator that many of them originated 
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