PREDATION— ERRINGTON 



247 



most cases where quail were represented, remains of some other prey 

 would predominate. A quail victim as a rule would be completely 

 eaten, but often on different days or by different oavIs, and so would 

 be represented in two or more pellets. 



Experience on the observational areas has shown that quail 

 remains in less than 6 percent of winter pellets (in good-sized lots) 

 ordinarily means a fairly light horned owl pressure upon quail popu- 

 lations running from 30 to 100 birds per square mile. This repre- 

 sents losses of the sort that even well-situated populations may be 

 expected to suffer and seems largely to take the place of the losses 

 from age and accident which would obviously go on anyway in the 

 total absence of predators. 



Table 1. — Horned owl pressure upon icintering tobwhite populations 



• Area A was at Prairie du Sac, Wis.; B and C, at Pine Bluff, Wis.; E and F at Madison, Wis.; O and H 

 at Des Moines, Iowa; and / at Ames, Iowa. J represents the combined data from 9 areas in southeastern 

 Iowa. 



However, when quail remains occur in 10 or 15 percent or an even 

 higher percentage of the pellets, it may be suspected that something 

 is wrong with the quail, themselves, or that there are too many of 

 them in the environment they are trying to occupy. 



Weakness of individual birds, as from hunger, injuries, or disease, 

 is more apt to predispose them to capture by hawks than by owls, 

 but handicapped ones are taken by owls, also. In a number of 

 instances, birds were killed by horned owls seemingly because they 

 fell into unsafe living habits or were not as adaptable as they might 

 have been in the face of danger. 



