1786 



The Cornell Reading-Courses 



great homed owl, in spite of its poultry-thieving habits, is not without its 

 value because of the numbers of rabbits, rats, and mice that it destroys. 

 The value of owls is best appreciated in nursery districts, where losses 

 of thousands of dollars have been entailed by mice and rabbits girdling 

 the young trees in winter. In some places it is imperative to wrap the 

 young trees in tarred paper or otherwise protect them from the ravages 

 of these small rodents. 



At times when conditions for their growth and reproduction have been 

 advantageous for several years, great plagues of these mice have occurred, 



PREPARED AND PHOTOGRAPHED BY G. A. BAILEV 



Fig. 17. — Owl pellets and skulls of mice removed from them 



the entire country being overrun with them. Indeed, considering their 

 reproductive capacity it seems remarkable that plagues do not occur 

 more often. The common field mouse has five to eight young at a litter, 

 and four or five litters in a year. Allowing for only thirty young in a 

 year from each pair, in five years the offspring from a single pair would 

 number over two million. Such valuable aid as the owls render in keep- 

 ing down this increase should therefore never be overlooked, even though 

 it goes on so inconspicuously. 



At times, however, their aid is very conspicuous. We find recorded 

 in many of the European chronicles, great flights of owls following the 

 plagues of voles, attracting the attention of every one and finally so 

 reducing the nxunbers of the voles that they were no longer obnoxious. 



