10 THE IMPORTANCE OF BIRD LIFE 



gulls reap a rich harvest of eggs and nestlings. 

 Condors, until driven off by watchmen, created 

 much havoc among the great guano rookeries of 

 Peru. Skuas hold the penguins of anarctic re- 

 ^ons in check. 



From the foregoing it would seem as if the odds 

 a,gainst survival are so overwhelming th,at birds 

 wdU soon be but memories of the past. The limit- 

 ing barrier, however, is not so mighty as it ap- 

 pears. Birds as a whole are extremely prolific. 

 When matured, owing to their power of flight, 

 they are difficult of capture. Finally, they 

 carry on a not ineffective strife with their en- 

 emies, inflicting at times as much damage as they 

 receive. Thus, while certain hawks and owls 

 prefer a diet of bird flesh, others, like the red- 

 tailed or so-called "hen-hawk," the American 

 sparrow-hawk, and the majority of owls, subsist 

 mainly on "vermin" in its varying forms. Some 

 kites and another "hen-hawk," the red-shouldered 

 species, delight in the flesh of lizards and snakes. 

 Harmful rodents, such as field-mice and rats, all 

 of which will break into a succulent egg with 

 pleasure, are mainly kept within bounds by the 

 birds. 



Being thus able to hold their own, birds play no 

 mean part in the economic relations of mankind 

 lay limiting the rodent pests which destroy crops ; 

 but this is of comparatively small moment in the 

 broAdei* field of Nature. Birds have a greater 



