180 THE STORY OF BIRD-LIFE. 



Besides these, as already hinted, we have 

 occasional stragglers. Such, for instance, are 

 many North American birds breeding in high 

 northern latitudes ; which, on their return home, 

 get blown out of their course by violent westerly 

 gales. 



But how is it, some will naturally ask, that 

 we see little or nothing of all this movement ? 

 Chiefly, we may answer, because for the most 

 part it takes place at such great altitudes as to 

 make it invisible and inaudible. What we do 

 see and hear is only an indication of what is 

 going on above. 



Mr Chapman, in America, by directing a power- 

 ful telescope towards the moon, has detected birds 

 passing at night in great numbers at a height 

 of from one to (?) five miles. Similar observations 

 have been made by day, by directing a telescope 

 against the sun. It seems to be only in stormy 

 or cloudy weather that migrants descend low 

 enough to be seen or heard. Our lighthouse- 

 keepers have rendered valuable aid in observa- 

 tion of the movements of the birds which pass 

 their stations. Their records have been pub- 

 lished in a series of reports instigated by the 

 British Association, the net result of which will 

 be shortly given to the world by Mr Eagle 

 Clarke, one of our greatest authorities on bird- 

 migration. It has been shown that during bad 

 weather the birds descend, and then seem to 

 be attracted to, and dazzled by, the powerful 

 beacons of the lighthouses and lightships — an 

 attraction which proves fatal to thousands, for 

 in many cases they are killed instantly by the 



