February 
same place, but frequently to nest in the same 
tree year after year, we may well believe that 
only some strong necessity can drive them an- 
nually so far away. 
With the exception of the very few that are 
permanent the year round, such birds as sum- 
mer in this region move southward in the fall, 
not only for warmth, but doubtless, in many 
cases, for the more potent reason that the fruit, 
grain, insects, etc., on which they have been 
feeding are no longer obtainable in this lati- 
tude. Thus the bobolink is also called ‘‘ rice- 
bird,’’ indicating the character of its sustenance 
while in the south. It may well be doubted 
whether the robin lacks the physical hardihood 
to withstand a northern winter, as it is fre- 
quently found in New England throughout that 
season ; but in the absence of fruits, grubs, and 
especially earth-worms, which are its main sub- 
sistence, it has a very precarious existence, and 
ample cause for retirement to the south. 
On the other hand, the hardier species that 
from one cause and another summer in the far 
north, like nuthatches, kinglets, and crossbills, 
coming southward at the approach of cold 
weather, find in this latitude both a tolerable 
climate and adequate subsistence in the eggs 
51 
4; j 
