WHERE SWALLOWS ROOST 97 



rounding country and in the evening return to the 

 marsh to sleep. In the evening they fly low, and 

 the altitude and time of their flight make them con- 

 spicuous. In the morning they fly high, as though 

 bound to some distant feeding ground, and at so 

 early an hour that they usually escape observation. 

 The evening flight, therefore, is generally considered 



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t 



i 1 > ' I / — -yv 



48. " Bird notes " — Tree Swallows. 



as truly migratory, when, in fact, the same birds 

 doubtless pass over a given locality night after 

 night, perhaps for weeks, in returning to their 

 roosts in the marshes. 



These evening flights begin about two hours and 

 a half before sunset, when the birds, after resting 

 during the late forenoon and early afternoon, usu- 

 ally on some telegraph wire,""* begin to wheel and 



