CHAPTER XXV 
THE MIGRATION OF BIRDS 
The migration season is of especial interest. It brings 
to us for at least a short period many birds belonging in other 
regions, including some that raise their young within the 
arctic circle and spend the winter in the tropics. In this 
great movement all birds take part except some of the perma- 
nent residents, such as our Prairie Hens and English Sparrows. 
How Far. — The length of these journeys depends upon the 
bird’s food. Insect eaters are obliged to go far enough south 
for the winter to find insects in sufficient abundance at that 
season. This takes the majority of them to Mexico, while 
many go farther, — the Oriole, for example, to Central Amer- 
ica, or the northern part of South America, and the Bobolink 
to southern Brazil. Birds like the Robin, that are willing to 
live on seeds and berries, merely go far enough south to get 
out of the heavy snowfall that covers their food, and beyond 
the range of severest cold. Generally speaking, birds that 
stay till late in the fall do not go far south and are the first 
__to return in the spring, while those that leave us first go the 
; “farthest and return last. Some birds that live the greater 
portion of the year in arctic regions consider the Dakota winter 
quite mild. Thus the Snowy Owl and the Snow Bunting come 
south to spend the coldest part of the season with us. Again, 
some birds move but a few hundred miles, others go from arctic 
regions to the southern part of Argentina every fall and return 
ae = 261 
