No. 4.] BIRDS USEFUL TO AGRICULTURE. 43 



apparently inexhaustible amount of this material found on 

 the Chincha Islands may be gained from the fact that the 

 deposits covered the three islands in some places to a depth 

 of ninety to one hundred feet. The demand for this material 

 grew to such an extent tbat by 1850 the price in the United 

 States had advanced to fifty dollars per ton, and it is stated 

 that five million tons have been imported into England alone. 

 In 1853 the Peruvian government, which controlled the 

 islands, surveyed them, and reported that there were still 

 more than twelve million tons available. So great has been 

 the demand, however, that this enormous quantity has now 

 been practically exhausted. The call for the new fertilizer 

 became so great and its price so exorbitant that American 

 enterprise (under the encouragement of an act of Congress) 

 began to explore the Pacific and the Carribbean Sea in a 

 search for unclaimed islands. Claims under this act have 

 now been filed with the United States government to about 

 seventy-five islands, and many others have been discovered 

 by the citizens of other nations in difierent parts of the 

 world.* Of late years, however, the demand for concen- 

 trated fertilizers has resulted in their manufacture, so that 

 they have largely taken the place of guano in intensive culti- 

 vation. But this subject presents itself in another aspect. 



All along the Atlantic coast, from Maine to Florida, there 

 are rocky or sandy islands which were once the breeding 

 places of innumerable sea fowl. There are also many 

 swam[)S and marshes where countless ducks, herons and 

 other water and wading birds once bred. These birds were 

 constantly gathering a harvest from sea, lake and river, in 

 the shape of fish and other marine or fresh-water animals. 

 The digestion of these birds is remarkably rapid. They 

 require an enormous quantity of food. Therefore, they must 

 have contributed considerably toward the building and 

 enrichment of the soil of our originally barren coasts and 

 islands. If they increase under })rotection and reoccupy 

 their former breeding grounds, a double benefit to agricult- 

 ure will ensue. 



Aside from soil fertilization, the relation of birds and 

 other animals to agriculture depends mainly upon the char- 



* " A Review of Economic Ornithology in the United States," by Dr. S. T. Palmer, 

 Year Book, Department of Agriculture for 1899, pages 278, 279. 



