ORNITHOLOGICAL OBSERVATIONS 269 



bird to increase its insect food. More commonly do 

 we see birds, for the same purpose, in company with 

 other animals. We see starlings, dronoos, ecrrets 

 living- in the closest friendship with cattle to secure 

 the insects flushed from the pasture. Buffalo-birds 

 and rhinoceros-birds attend their hosts for the ticks on 

 their bodies. Ant-thrushes accompany the foraging 

 ants of America. Similarly have I seen clouds of 

 swallows following the ranks of an army to capture the 

 myriads of insects driven into the air by the advancing 

 troops. 



The flight of birds has often attracted the attention 

 of observers. One day I was watching a pair of 

 ravens, Coi"vus corax, chasing one another in the air 

 as though they were indulging in a game of sport. 

 The pursuer would hurry forward as if trying to catch 

 and quarrel with its playmate, but on reaching it, 

 instead of making an attack, it would deliberately roll 

 itself to one side and turn one or more somersaults in 

 the air. Then recovering itself, it would continue the 

 chase only to repeat the same gymnastics. It gave 

 the impression that the ravens were enjoying a game 

 of bird life. This tumbling in the air is a singular 

 habit. Rooks are often seen to indulge in it as they 

 wend their way home to roost ; a single bird will at 

 times fall out of the flock and take a few tumbles in 

 the air. In the case of the birds of prey, the habit of 

 tumbling is often associated with courtship. Kites, 

 Milvus govinda, at the nesting season, will often roll 

 about in partial revolutions, though I never saw one 

 take a complete turn. That most magnificent bird, 

 the lammergeyer or bearded vulture, Gypactus bar- 

 batus, indulges in a similar performance. It is a 



