270 A NATURALIST IN HIMALAYA 



splendid sight to see a pair of these huge birds in 

 amorous courtship, tossing, rolling, turning themselves, 

 displaying to the very full their complete conquest of 

 the air. I once saw a pair of Pallas's fishing eagles, 

 Haliaetus leucoryphus, engaged in somewhat similar 

 evolutions. One of the pair, a splendid bird, I suppose 

 the male, used to ascend to a considerable height while 

 the female sailed along slowly near the ground. All 

 of a sudden the male would swoop down upon his 

 partner through a depth of four or five hundred feet. 

 In a few moments he reached her. Then the female 

 would escape his blandishments by gently rolling over 

 to one side so as to make a complete lateral somersault 

 in the air. Then again the male would ascend, and 

 the two great birds would continue to repeat the same 

 strange nuptial play. This habit of turning in the 

 air is also followed by that well-known bird, the 

 scavenger-vulture, Neophron percnopterus. Though 

 this bird is strong upon the wing, yet it allows itself 

 sometimes to be persecuted by crows. I have watched 

 the crow darting on the vulture from above, but the 

 great bird seemed unable to defend itself; it merely 

 endeavoured to escape its attacker by rolling itself 

 over in a somersault through the air. Certainly this 

 habit of tumbling is a strange performance. With 

 some birds it is probably a matter of play, with others 

 a manifestation of sexual enjoyment, with others a 

 mode of escape from an enemy. I have mentioned 

 these cases that have come under my notice since 

 they may suggest a method by which tumbler pigeons 

 might have developed their peculiar habits. 



The circling flight of the larger birds of prey is 

 more open to investigation. It is indeed a remark- 



