AT ee eg 
NIGHT-HAWK. 169 
the birds came to it, like deer to a salt-lick. They 
were so eager that, in some places, they actually 
nibbled almost through the wood until, as Mr. 
Hough says, the freezer looked as if mice had 
been gnawing it. 
RAE 
NIGHT-HAWK; BULL BAT. 
Just at twilight, above the chippering of the 
chimney swifts, you will often hear sharp cries 
that startle you into looking overhead. Circling 
in the air after insects you will see large, dark 
colored birds, with narrow, clear cut, crescent 
shaped wings and slender bodies. If they come 
near enough you will catch the white bars on their 
wings as they fly rapidly by. If your eyes and 
glass are both good perhaps you will get a glimpse 
of their curious great mouths, wide open as they 
fly; and then the mysterious disappearance of the 
swarms of insects that hover in the air will be 
picturesquely explained. 
A study of bills would be as suggestive as in- 
teresting. With each group, as we have seen, the 
form is modified to suit the needs of the birds, — 
the woodpeckers have long strong bills for ham- 
mering and excavating; the sparrows short stout 
cones for seed cracking; the vireos long slender 
bills for holding worms; and the flyeatchers bills 
