Seasonal selectivity of Magellanic horned owl (Bubo magellanicus) on rodents

This study examines prey selection by Magellanic horned owls (Bubo magellanicus) in an ecotonal steppe area of northwestern Argentine Patagonia, and analyzes morphological and behavioral traits of the owls main rodent prey. The owls diet was studied for two years, along with field estimates of rodent abundance. The frequency distribution of rodents was significantly different from that estimated from trapping, indicating that Magellanic horned owl behaved as a selective predator. Eligmodontia morgani and Abrothrix xanthorhinus, the smallest species inhabiting open areas, were consumed in lower proportion than their occurrence estimated from the trapped sample, whereas the larger Abrothrix longipilis and Oligoryzomys longicaudatus, which inhabited bushy habitats, were eaten in a greater proportion than their estimated abundance. It is suggested that distinctive morphological and behavioral characteristics among prey interacting with the owl hunting strategy, accounted for their differential vulnerability to predation.