MIGRATION . 
123 
Once or twice I caught him and stroked his 
head and neck. He was quiet enough while I 
touched him, but the moment my fingers left 
him, he slipped away out of sight. When 
taken out of doors and set free, he darted into 
the nearest stone wall and was seen no more. 
Birds of the upper air which feed on insects 
depart early. The eaves swallows and martins 
go while some mothers are still sitting on be¬ 
lated eggs. Bank swallows, barn swallows, 
night-hawks, and many of the tyrant flycatchers 
have vanished by the time the maples begin to 
flame upon the mountain-side. On the 3d of 
August, 1891, I saw about twenty martins in 
the dead tree. They were very noisy, and 
evidently excited. While watching them I saw 
in the zenith what looked like a cloud of insects. 
My glass showed it to be a large flock of birds, 
apparently swallows, moving in a great circle. 
After a time all but one of the martins in the 
tree flew away and were gone many minutes, 
the birds in the sky also disappearing. The 
martins returned, however, to the one which 
had not flown, and shortly after I again discov¬ 
ered the bird cluster in the sky. After fresh 
noise and flutterings of wings the martins 
finally flew, and no more were seen near the 
lake that season. Often in an August afternoon 
the lake will be apparently without birds, when 
