THE BIRD AND THE TREE 



although these owls differ from their congeners 

 in the choice of a nesting site, and that their 

 habit is not normally arboreal, they are none the 

 less quite ready to take a perch on a suitable 

 bough whenever occasion offers. 



Two classes of birds, most dissimilar in habits, 

 may now be considered in relation to trees — ^the 

 swallows and the pigeons. The swallows, with 

 which for our present purpose we include the 

 swift (it is always difficult, indeed, mentally to 

 divorce the swift from the swallows, remembering 

 the number of strongly marked characteristics 

 that the birds have in common) cannot be re- 

 garded as birds possessing a true and natural 

 affinity for tree-life. Although the swallow itself, 

 the house-martin, and, more rarely, the sand- 

 martin, all alight upon boughs, they appear to do 

 so merely to rest, selecting for the most part a 

 dead and conspicuous branch. They never move 

 freely in dense foliage, as though delighting in the 

 play of light and shadow in the leaves, as the 

 willow-wren, whitethroat, and others of the 

 smaller races may be seen to do. For them the 

 tree is merely a fixed station, to be deserted 

 directly the tired wing is sufficiently restored to 

 permit the wanderer to return to its native 

 element. In the case of the swift, so truly is he 

 a creature of the air that if it were not for the 

 exigencies of nesting it would seem he would 

 spurn earth altogether. 



There is strong reason to think that swifts, at 

 times, ascend to a great height, and spend the 

 whole night in the air. Mr. W. H. Hudson 

 assumes this to be so, and he records certain in- 

 teresting observations in support of his belief. 



We have never heard of a swift attempting to 

 alight upon a tree, nor even upon a roof. His 

 feet, constructed with two toes in front and two 



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