NIGHT-HA WK. 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. 



LIIL 



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 flycatchers bills 



