THE WOODPECKERS. 
133 
its young; these holes vary in depth, according to 
circumstances, from six inches to nearly three feet. 
In its usually upright position against the body of 
the tree, it must necessarily lie pretty close in order 
to work to advantage ; hence the legs are short and 
muscular, and the toes, which are arranged two before 
and two behind, are well calculated to take a firm 
hold upon the bark and retain it for a long time. 
This upright position of the body is also more stead- 
ily maintained by the assistance of the tail, which is 
somewhat wedge-shaped, the more central feathers 
being more rigid, and having the shafts very thick, 
and stout, and sharp pointed, which, when placed 
against the trunk of the tree, serve as a support. The 
flight of the Woodpeckers is also singular, consisting 
of a frequent repetition of a few rapid and powerful 
strokes of the wings, which produce an undulating 
motion through the air, the body rising and falling 
with the alternate opening and closing of the wings. 
They are sprightly and active in their motions, alight- 
ing upon a tree and moving around the whole circum- 
ference, backward and forward, or ascending spirally 
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