THEIR PLACE IN NATURE 19 



besides several hawks that prey upon snakes and 

 lizards, the turkey-vulture exhibits a fondness 

 for the eggs of alligators, a habit which serves 

 in some measure to hold those reptiles within 

 proper bounds. 



Sea-birds are harbingers of destruction to the 

 fish group. Most of them live entirely upon 

 fish. Gulls, albatrosses, and fliers of that type 

 annually devour millions of tons. Other than 

 these, there exist numerous colonies of fish-eat- 

 ing cormorants, boobies, and pelicans, to say 

 nothing of penguins, auks, and sea-ducks. A 

 single colony sometimes consists of hundreds of 

 thousands of individuals, even of millions. So 

 plentiful are the cormorants and other water- 

 fowl of the St. Lawrence Gulf that they darken 

 the face of cliffs already whitened with their ex- 

 creta. And the St. Lawrence is only one of 

 many similarily infested regions of the earth. 



Parts of the antarctic continent form another 

 area with its millions, as do the coasts of Alaska, 

 Labrador, and Peru, and every one of the aquatic 

 birds that live there is a fish-eater. Allowing one 

 pound of fish a day to a cormorant, — a low esti- 

 mate, — ^we can reckon that a small colony of 

 100,000 birds will consume fifty tons, or virtually 

 two full carloads, every twenty-four hours. With 

 the million upon million individuals of this single 

 family in existence, and other millions of their 



