WIND AND FLIGHT 121 



wind near the earth's surface increases in velocity 

 with altitude. 



Rising. 

 Almost everyone has noticed that birds always 

 face the wind when they rise. In the case of big, 

 heavy birds this is particularly striking, for they 

 will often fly some little distance in the wrong direc- 

 tion, in a direction in which they certainly do not 

 wish to go, in order to get the help of the wind in 

 rising. When they have gained some little altitude 

 they turn and make for their objective. When a 

 steamer disturbs a Gannet floating on the water, if 

 there happen to be a fresh breeze blowing from the 

 steamer towards him, he will in rising head towards 

 the imagined enemy, and not till he has at his 

 disposal a few feet of altitude will he turn and make 

 off rapidly with the wind behind him. Oyster- 

 catchers will do the same thing. Once, when walking 

 along the sands south of the Solway Firth, I saw 

 hundreds of them in front of me. There was a 

 strong breeze blowing from me to them. Hence it 

 was much easier for them to make a start if they 

 flew towards me till they attained some slight 

 elevation. They therefore flew a little way towards 

 the disturber of their peace, then turned and settled 

 some way off upon the sand. I put them up a good 

 many times, and each time they began by flying a 

 short distance towards me ; so important is it for 

 a bird to get the help of the wind in rising. I once 

 saw a Cormorant fly a quarter of a mile or so in the 

 wrong direction. He had been feeding with his 

 fellows, which had all, after the meal, retired to a 

 rock, where they were drying their wings in the usual 



