BIRDS OF THE NIGHT. 289 



upwards at the bottom of his descent, a singular note 

 resembling the twang of a viol-string. This sound has 

 been supposed to be made by the action of the air as the 

 bird dives swiftly through it with open mouth. This is 

 proved to be an error by the fact that the European 

 species makes a similar sound while sitting on its perch. 

 Others think that this diving motion of the bird is de- 

 signed to intimidate those who seem to be approaching 

 his nest; but the bird performs the same manoeuvre 

 when he has no nest to defend. This habit is peculiar 

 to the male, and it is probably one of those fantastic 

 motions which are noticed among the male Doves as arti- 

 fices to attract the attention of the female. 



This twanging note, made during the precipitate de- 

 scent of the Nighthawk through the air, is one of the 

 picturesque sounds of Nature, and is heard most fre- 

 quently in the morning twilight, when the birds are col- 

 lecting their early repast of insects. If we should go 

 abroad before daylight or at the earliest dawn, we might 

 see them circling about, and hear their cry frequently 

 repeated. Suddenly this twanging sound excites our 

 attention, and if we were not acquainted with it or 

 with the habits of the bird, we should feel a sensation 

 of mystery, for there seems to be nothing like it in na- 

 ture. The sound produced by the European species is a 

 sort of drumming or whizzing note, like the hum of a 

 spinning-wheel. The male begins this performance about 

 dark, and continues it at intervals a great part of the 

 night. It is effected while the breast is inflated with 

 air, like that of a cooing Dove. The Nighthawk inflates 

 its breast in a similar manner, and utters a similar sound 

 when any one approaches the' nest. 



The habit of the Whippoorwill and Nlghthawk of sit- 

 ting lengthwise and not crosswise on their -perch has 

 excited some curiosity ; for it is well known that these 

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