RELATION TO AGEICULTURE 25 



breed upon and grow strong. The great Balance 

 of Nature was upset. 



Only one course remained for Nature to pursue 

 at this crisis. Her policemen, the birds, were 

 hurried to the rescue. They alone formed a 

 living barrier through which the unruly ones 

 would find it diflBcult to drive. 



Unfortunately it took men several thousand 

 years to learn that birds were their friends and 

 helpers. During all that period birds were con- 

 sidered detrimental in every way to the best in- 

 terests of husbandry. Birds stole grain, they 

 robbed the poultry yard, they consumed fruit, 

 and they destroyed the shoots of young plants; 

 they were bad through and through. Of so much 

 man assured himself as an eye-witness, and he 

 did not think to look further. 



At last came a day when the study of natural 

 history was accorded a place among the sciences. 

 People began to specialize in ornithology. To 

 their amazement, they discovered that all birds 

 were not so black as they had been painted. In- 

 deed, from the analysis of the stomach contents 

 of thousands of individuals, it was found that 

 scarcely any of them were bad. Men learned 

 that for every fowl the so-called hen-hawks cap- 

 tured, most of them devoured a hundred or more 

 rats and field-mice. It came to be understood that 

 the destruction caused by 'those rodents far ex- 

 ceeded the money value of a few fowls. The bal- 



