CHAPTER XVIII 

 BIRDS AS RELATED TO AGRICULTURE 



BIRDS rely largely upon weed seeds and insects for their 

 food. For this reason they are of inestimable value in help- 

 ing to control weeds and in holding insects in check. The 

 good they do is not sufficiently appreciated. It will there- 

 fore be worth while to consider some of the facts of bird life 

 as related to agriculture, showing how birds protect farm 

 plants from insect injuries and from weeds to a certain extent. 



Food of adult birds. Most of our common birds are 

 either seed eaters or insect eaters. In certain seasons they 

 may eat fruit, but the damage done to cultivated fruits by 

 birds is generally offset by the good they do in other ways. 



Birds as destroyers of weed seeds. We have seen that 

 one reason why weeds are able to succeed so well in establish- 

 ing themselves is that they produce great quantities of seeds. 

 When weed seeds have been produced and scattered, little 

 can be done toward control until they have developed into 

 seedlings the following season. It is especially difficult to 

 destroy seeds which have fallen on the ground. A large 

 amount of weed seeds is eaten by birds. The number of 

 seeds found in the stomach and crop of a bird, representing 

 a single feeding period, gives some idea of the service rendered 

 in the destruction of weed seeds. For example, a red- winged 

 blackbird was found to have eaten in one feeding period 

 1800 seeds of ragweed; a bob white, 5000 seeds of pigeon 

 grass; and a mourning dove, 9200 seeds of pigeon grass. 



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