Tail. 



411 



tance, free of barbs, the tips l)eing thus conijjosed of a num- 

 ber of bare spines whioh are a(hiiirably a(la})(e(l lo catch 

 in the irreguhirities of hollow trees, or, as now in their 

 recently adopted homes, in the roughness of chinmey- 

 bricks. I one day caught a Chimney Swift and ])laced 

 it against a varnished wall composed of composition 

 bricks; and, smooth though the surface was, the bird's 

 tail and toes held it firmly, not sli])j)ing even a quarter 

 of an inch. After photogra])hing it, I watched it for 

 some minutes and saw the bird shift its position several 

 times, moving always with a certainty and surety of 

 grasp most inexplical)le. 



The tails of woodpeckers and creepers are not tlius 

 denuded at the tip, but they are stiffened tliroughout 

 and are very elastic (Fig. 240). When a woodpecker 

 brings up against a comparatively smooth tree-trunk, its 

 certainty of hold is a perfect bit of magic. Then when 

 it braces itself and sets to work to hammer a hole into 

 the wood, or to excavate its nest, how the tail-feathers 

 bend and spread, buttressing themselves against every 

 roughness, the elasticity of the feather-tips allowing them 

 to slip into ever}' crevice! 



In many birds the tail is a perfect index of the emotions, 

 doing much to compensate for the lack of facial expression. 

 Especially is this true of the wrens, those feathered bundles 

 of tireless energy and curiosity, whose tails, upturned so 

 high that they fairly tilt forward over the back, twitch 

 and jerk with every passing mood. Even the genetic 

 individuality of a species may be hinted at in the way 

 it carries its tail; quiet, soft-mannered birds holding it 



