82 BIRDS THROUGH AN OPERA-GLASS. 
unsuspecting insect he has been lying in wait for, 
and before you breathe settles back on the branch 
with a spasmodic jerk of the tail. 
And now, as he sits looking for another victim, 
you have a good chance to note, through your 
glass, the peculiarities of the bill that gave such 
a resounding “click.” Birds’ bills are their tools, 
— the oriole’s is long and pointed for weaving, 
the chickadee’s short and strong to serve as a 
pickaxe; but when the nest does not call for a 
tool of its own the bill conforms to the food habits 
of the bird,—as the white man’s needs are met 
by knife and fork, and the Chinaman’s by chop- 
sticks. So the bills of the robin and bluebird, 
you remember, are long, thin, and slender, — well 
fitted for a worm diet, — while the sparrows, who 
live mostly on seeds, have the short, stout, cone- 
shaped finch bill. In the same way flycatchers’ 
bills are specially adapted for their use, that of 
catching the insects upon which they live. At 
the base there are long stiff bristles, and the upper 
half of the bill hooks over the lower so securely at 
the end that when an insect is once entrapped it 
has small chance of escape. 
The pheebe is fond of building in a crotch of 
the piazza, on the beams of old sheds, and under 
bridges, apparently indifferent to the dust and 
noise of its position ; but away from the immediate 
haunts of man it usually nests in caves or rocky 
ledges, and sometimes takes possession of the up- 
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