Physical and Behavioral Correlates of Prey Vulnerability to Barn Owl (Tyto alba) Predation

Prey vulnerability to barn owl (Tyto alba) predation was investigated using three rodent species-Microtus pennsylvanicus, Peromyscus leucopus and P maniculatus. Relationships between rates of prey capture and the species, age, sex, body size and behavior of prey were assessed. Microtus were captured significantly more often than individuals of either Peromyscus species. Adults were captured more often than juveniles in each species except P maniculatus. Capture rates of males as compared to females differed significantly among juveniles of each prey species but not among adults. Differential vulnerability of prey was correlated with prey size and behavioral characteristics influencing their vulnerability to capture. The results indicate that by foraging preferentially on Microtus, barn owls could maintain high levels of energy intake while minimizing foraging time and costs.