NATURAL HISTORY OF SOUTH AFRICA 



is not a sufficient food supply numbers die off, and the 

 balance of Nature is restored. This is not so with 

 many of the seed-eating kinds. When the seeds of 

 grass and other wild plants and insects fail them, they 

 attack the farmers' grain crops, and their numbers have 

 to be reduced by human agency. Birds rarely store 

 food. They seek and consume what food is needful 

 for the day, and their movements are consequently 

 guided and determined by their food supply. When 

 insects are superabundant in any locality, the birds 

 soon become aware of the fact, and flock in from the 

 surrounding districts and prey upon the pests, leaving 

 only a few survivors lurking in hiding places. 



Birds have a high bodily temperature, and to keep 

 it up a large amount of food is needful. When 

 deprived of food, a bird rapidly dies. Mammals, 

 with but few exceptions, can fast for a month and 

 more. It is a common practice for people to abstain 

 from all food for two weeks to a month for various 

 health reasons. Food is, therefore, an ever-present 

 necessity for the bird. 



The jack hanger or fiskal shrike (Lanius collaris) 

 is one of the few exceptions amongst birds which 

 store food. When insects are abundant it catches 

 and impales them on thorns and barbed wire fences 

 for its future needs. I have frequently seen a large 

 assortment of beetles, locusts, and mice stored away 

 by a pair of fiskal shrikes, and have kept them in 

 aviaries to study their habits. 



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