ORNITHOLOGICAL OBSERVATIONS 277 



in its victory, it sails higher and higher above the 

 broken ranges, a tiny speck in the firmamental blue. 



The rise up wind is easy to observe even in a gentle 

 breeze. I have frequently been able to determine the 

 direction of the wind at altitudes far above me by 

 watching the gain to windward in every circle, and to 

 predict the point from where the wind would blow 

 when it was not yet perceptible on the ground. These 

 predictions used to bring conviction that wind was all 

 essential to a bird if by circling alone it was to gain 

 in height. When, in the early morning, there often 

 was no wind, the kites refused to soar ; but on the 

 appearance of the first breeze, they felt the energy 

 that was to raise them, and in numbers they rose aloft 

 circling freely in the strengthening breeze. When the 

 wind is streaming in the heavens, the gorges are often 

 sheltered from its force and the birds are unable to 

 rise in circles until they clear the confines of the gorge. 

 While sheltered between the rocky walls, they move 

 by an alternate flapping and gliding flight, rising when 

 they flap and sinking when they glide ; but as soon as 

 they overtop the gorge and feel the flowing wind in 

 their pinions all flapping ceases, for the wind now 

 supplies them with the force that in the shelter 

 demanded the energy of their wings, and they rise 

 higher into the heavens by free circling flight. 



How often has it been asked, "Why do birds, with 

 outstretched, motionless wings, circle for hours aloft 

 in the sky ? " I believe they circle, not because they 

 enjoy circling, but because, if they are to remain aloft 

 without continual muscular effort, then they must 

 circle. A kite or vulture has to soar far above thr 

 mountains and, with piercing eye, scan every valley 



