Tails 411 
tance, free of barbs, the tips being thus composed of a num- 
ber of bare spines which are admirably adapted to catch 
in the irregularities of hollow trees, or, as now in their 
recently adopted homes, in the roughness of chimney- 
bricks. I one day caught a Chimney Swift and placed 
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 slipping even a quarter 
of an inch. After photographing 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 inexplicable. 
The tails of woodpeckers and creepers are not thus 
denuded at the tip, but they are stiffened throughout 
and are very elastic (Fig. 240). When a wocdpecker 
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 every 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 
