22 BIRD BEHAVIOUR 



In respect of the activities of the soaring birds of 

 prey, it has been noted that the highest soarers are 

 the latest to rise, the Vultures not taking the sky 

 till after the Kites, and none soaring till the sun is 

 well up, and it has been suggested that sun-lit air 

 has some favourable influence on soaring. Even 

 over here I have observed that a fine, sunny day in 

 winter or early spring will set the Black-headed 

 Gulls on the Thames soaring, but I always put this 

 down to their being inspired by the fine weather 

 with thoughts of their home breeding-grounds, and 

 a preparation for travelling thither ; while I 

 should have said that the connection between sun 

 and soaring in the East was simply that the larger 

 carrion-feeders needed clearer air, and had to 

 mount higher, as their food was harder to find ; 

 but after an absence of a dozen years from India I 

 am quite willing to admit I may be mistaken. 

 However, sunny weather in autumn does not 

 seem to take the Gulls aloft, as I have had an oppor- 

 tunity of observing recently. 



It is noticeable that soaring birds are never still, 

 but keep on describing circles as they float on 

 extended motionless wings ; as a matter of fact 

 they appear to descend a little and then use the 

 impetus thus gained to rise again, so that they are 

 really making spirals. A bird, except in a strong 

 wind, can only stand still in the air by constant and 

 rapid wing- action ; this is the feat of hovering, of 

 which the Kestrel is the most familiar exponent in 

 this country during most of the year, though the 



