CHAPTER VIII 



BACKGROUND-PICTTIRING ON OBLITERATIVELY-SHADED BIRDS, CONTINUED. 

 THE VARIOUS PATTERNS OF SCANSORIAL BIRDS 



SCANSORIAL birds are for the most part tree-trunk climbers. They are 

 the Woodpeckers {Picida), the Wrynecks {Jyngida), the Nuthatches 

 (Sittince), the small Northern Creepers (Certhiidcs), the Wood Creepers 

 (Dendrocolaptidce), and a few other forms. 



Most of these birds — notably both families of Creepers — spend almost 

 all their time in a nearly vertical position, clinging to the bark of tree trunks 

 with claws and tail, or claws alone. The Nuthatches climb head-first down- 

 ward as well as upward, the others seldom or never do. 



In spite of the erect climbing-position in which they spend their lives, 

 these birds are almost without exception dark on the back and light on the 

 breast and belly, and many of them have a delicate, complete gradation from 

 the dark side to the light. The underside may be pure white, as in the case 

 of many woodpeckers, or brown, barely lighter than that of the back, as in 

 some of the DendrocolaptidoR. But in the whole catalogue of species we 

 know of none which is not thus counter-shaded, more or less pronouncedly. 

 But how, then, the reader may ask, does this regulation counter shading con- 

 form with these birds' vertical habit of life? The answer is plain. The solid, 

 leaf-crowned trunks up which they climb cut oflf the light from their breasts, 

 and almost all that reaches them strikes laterally or diagonally on their backs. 

 It is the same scheme over again, but carried out on a vertical instead of a 

 horizontal plane. 



The patterns of these climbing birds are extremely various, ranging from 

 none at all, as in some of the Wood Creepers, etc., to exquisitely elaborate 



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