VII 

 DAMAGE TO THE HUMAN FOOD SUPPLY BY MAMMALS 



We have briefly considered the bright side of the relation of mam- 

 mals to our food supply. The dark side is the destructiveness of cer- 

 tain species. It is impossible to make an accurate estimate of the dam- 

 age done by them. Even where an entire crop is destroyed, as some- 

 times happens, one cannot determine with certainty just the amount of 

 damage, as the value of an unharvested crop cannot be absolutely 

 known; much less is it possible where the damage is only partial, as 

 is usually the case. However, after making all allowances for possible 

 inaccuracies in estimates, the aggregate amount of damage from depre- 

 dations of mammals is appalling. 



We must admit also the impossibility of completely segregating the 

 damage to the human food supply from damage to food not directly 

 destined for human use, and in the estimates as published are often 

 included damage to commodities not usable for food of any animals. 

 Maize, or corn, as it is commonly called in America, is used to some 

 extent as human food, but is also fed in large quantities to cattle, 

 horses and hogs. Even the latter portion indirectly affects the human 

 food supply, as we eat the beef and pork derived from the cattle and 

 hogs that consume the corn. We do not eat grass or hay, but their de- 

 struction by rodents may affect the animals from which we derive 

 our meat and thus indirectly affect our food supply. 



In estimates of damage by house rats and mice is often included 

 damage to furs, rugs, textiles and many commodities not usable as food 

 for men and women. All this must be kept in mind in the use of esti- 

 mates herein contained, in order that they may not be misleading. 

 Rodents, because of their great numbers, are the chief offenders. Bell 

 has estimated the annual damage to crops in the United States by all 

 rodents, evidently including the introduced species, at $500,000,000, 

 with some special estimates for particular states, as follows: Mon- 

 tana, $15,000,000 to $20,000,000; North Dakota, $6,000,000 to 

 $9,000,000; Kansas, $12,000,000; Colorado, $2,000,000; California, 

 $20,000,000; loss to crops and pasturage from native rodents, 

 $300,000,000; damage to orchard trees by pine mice alone in one 



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