GEOGEAPniCAL IMPORTANCE OF BIRDS. 109 



The result is, that man has greatly reduced the numbers of all 

 larger marine animals, and consequently indirectly favored the 

 multiplication of the smaller aquatic organisms which entered 

 into their nutriment. This change in the relations of the organic 

 and inorganic matter of the sea must have exercised an influence 

 on the latter. What that influence has been we can not say, stiU 

 less can we predict what it will be hereafter ; but its action is not 

 for that reason the less certain.* 



Geographical Importa/nce of Birds. 



"Wild birds form of themselves a very conspicuous and interest- 

 ing feature in the staffage, as painters call it, of the natural land- 

 scape, and they are important elements in the view we are taking 

 of geography, whether we consider their immediate or their inci- 

 dental influence. Birds aft'ect vegetation directly by sowing seeds 

 and by consuming them ; they aflect it indirectly by destroying 

 insects injurious, or, in some cases, beneficial to vegetable hfe. 

 Hence, when we kill a seed-sowing bird, we check the dissemina- 

 tion of a plant ; when we kill a bird which digests the seed it 

 swallows, we promote the increase of a vegetable. JSTatm-e pro- 

 tects the seeds of wild much more effectually than those of do- 

 mesticated plants. The cereal grains are completely digested 

 when consumed by birds, but the germ of the smaller stone-fruits 



* Among the unexpected results of human action, the destruction or multi- 

 plication of fish, as well as of other animals, is a not unfrequent occurrence. 

 "Williams, in his History of Vermont, i. , p. 149, records such a case of the in- 

 crease of trout. In a pond formed by damming a small stream to obtain wa- 

 ter-power for a saw-mill, and covering one thousand acres of primitive forest, 

 the increased supply of food brought within reach of the fish multiplied them 

 to that degree, that, at the head of the pond, where, in the spring, they crowded 

 together in the brook which supplied it, they were taken by the hands at pleas- 

 ure, and swine caught them without difficulty. A single sweep of a small 

 scoop-net would bring up half a bushel, carts were filled with them as fast as 

 if picked up on dry land, and in the fishing season they were commonly sold 

 at a shilling (eightpence halfpenny, or about seventeen cents) a bushel. The 

 increase in the size of the trout was as remarkable as the multiplication of their 

 numbers. 



The construction of dams and mills is destructive to many fish, but operates 

 as a protection to their prey. The mills on Connecticut River greatly dimin- 

 ished the number of the salmon, but the striped bass, on which the salmoa 

 feeds, multiplied in proportion. — Dr. Dwight, Travels, vol. ii., p. 335. 



