PREDATION— ERRINGTON 245 



Of the predator species resident in this region, the great horned 

 owl {Bilbo virginianus) has been investigated the most thoroughly 

 and the most satisfactorily, both from the standpoints of its be- 

 havior and its food habits. From the quail observational areas 

 alone, nearlj'^ 2,500 horned owl pellets have been collected and 

 analyzed* and a large number of kills made by horned owls have 

 been recorded in connection with field studies. 



Correlation of the predation and population data from the above 

 areas is simplified by the fact that, of the two species upon which 

 an exceptional amount of research has been done, one proves to be 

 the chief predatory enemy of the other. 



The Cooper's hawk {Acciplter cooperi) and the goshawk {Astur 

 atricapillus) may on occasion be truly formidable enemies of quail; 

 but the horned owl has repeatedly demonstrated its ability to prey 

 upon quail if any wild predator can, and it possibly kills more quail 

 in the north-central States than all other wild predators together.^ 

 Quail remains have been found in as many as 10 of one lot of 30 

 horned owl pellets and in 19 of another lot of 85; and numerous 

 other large lots have contained remains in from 5 to 15 percent of 

 the pellets. 



The reader may conclude, at this point, that the case agamst 

 the horned owl as a quail enemy appears rather settled, and, as 

 concerns quail conservation, looks distinctly bad for the owl. 



Some may speculate further as to the role of the horned owl in 

 the econom}^ of nature and may contend that the direct damage in- 

 flicted upon the quail may be oft'set by indirect benefits resulting 

 from the horned owl's activities as a whole — if not indirect benefits 

 to the quail, perhaps to other wild creatures or to agriculture. But 

 whatever may be the arguments advanced by those who may defend 

 the horned owl, practically everyone appears to concede that heavy 

 depredations upon the highly esteemed bobwhite represent a re- 

 grettable loss and, moreover, a loss preventable in large measure 

 through reduction in numbers of the offending predator. 



Now, suppose that it were to become public knowledge, in a 

 community interested in the conservation of the bobwhite, that not 

 only were horned owls abundant over the choice quail range but that 

 each owl had been eating quail once a week, on the average, through- 

 out most of the winter and would likely continue to do so for the 

 rest of the winter and for weeks into the spring? In all proba- 

 bility, some action would be forthcoming, and it would be direct 

 action of an easily predictable and understandable kind. 



* Tor a discussion of tlie reliability of pellet analysis as a method of study, see Erring- 

 ton, P. L., Technique of raptor food habits study. Condor, vol. 34, pp. 75-80. 19.32. 



^ Predation by wild species should always be considered in a different category from 

 predation by modern man ; for discussions, see Errington and Hamerstrom, op. cit., 

 footnote 5. 



