Forested landscapes vary greatly in habitat structure and complexity due to natural and anthropogenic
disturbances that may alter forest attributes. Habitat structure along with temporal factors may directly
affect interactions between species, particularly those between predators and their prey. Our study assesses
the effects of habitat structure in prey intake of a small avian predator, the ferruginous pygmy-owl
(Glaucidium brasilianum) in semiarid forests of calden (Prosopis caldenia) in central Argentina. Overall, the
main prey of owls was small mammals, followed in importance by birds, insects and reptiles. The mean
abundance of mammals in the diet was affected by season and year, while the abundance of birds in the
diet was greater during spring-summer than during autumn-winter. As for insect prey, abundance of
birds in the diet was also greater in open than in closed forests. Habitat type seems to plays an important
role in the use of food resources by the ferruginous pygmy-owl in calden forests. Due to the recurrence,
spatial extent and remarkable effects of natural disturbances on habitat structure in these environments,
our results suggest that habitat type and structure should be taken into account in diet studies of forest
specialist avian predators in these habitats.