PILGRIMS OF THE NIGHT 



THE; migration of birds is one of the most 

 puzzling secrets of nature. We know very 

 little accurately and scientifically about it, 

 for the excellent reason that the phenomena 

 of these semi-annual pilgrimages are ex- 

 tremely difficult to observe. Birds as a rule 

 migrate in the night, and at such a great 

 height above the surface of the earth that, 

 even in the brightest moonlight, they are 

 seldom visible. The only intimations we 

 have of their passage (save when they cross 

 the disk of the moon) are the faint, eerie, 

 swiftly-vanishing notes that float down to us 

 through the air of a still spring or autumn 

 night. And even these notes, as a discrim- 

 inating writer on ornithology has pointed 

 out, are of little help in determining the 

 species of bird that may be speeding its way 

 over us at the time, because they are quite 

 different from the ordinary notes uttered 

 while these birds are residents of our woods 

 and fields. Any student of birds who has 

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