THEIR PLACE IN NATURE 13 



Limiting of vegetation is confined to the de- 

 struction of fruit and seeds. Birds excel in this. 

 Enormous quantities are annually done away 

 with. Much depends upon the type of fruit, 

 whether its mere digestion will serve to kill the 

 enclosed seed, or whether the seed will pass un- 

 scathed through the intestines and emerge ready 

 to germinate. If the fruit happens to be unripe 

 the seed naturally seldom survives. Although 

 birds each year consume millions of tons, they do 

 not succeed in rendering all the seeds sterile. A 

 large proportion, especially seeds of berries, live 

 to germinate after they have been evacuated. On 

 the other hand, a great number of weed seeds are 

 destroyed. 



It has been determined by experiment that the 

 vegetarians among birds fall into three natural 

 groups. The first is made up of those species 

 which grind and break up the hardest fruits and 

 seeds in their gizzards by the aid of pebbles and 

 gritty sand. Among these are the gallinaceous 

 fowl (e. g., turkeys, grouse, quail, and domestic 

 fowl), pigeons, ducks, titmice, sparrows, and 

 most finches. The smaller birds crush the seeds 

 in their bills before swallowing. 



The next group is partly composed of crows, 

 ravens, jackdaws, and jays. Hard-coated berry 

 seeds and cherry-pits pass uninjured through 

 their intestines or may be evicted through the 



