Effects of terra firme-forest structure on habitat use by owls (Aves: Strigiformes) in central Brazilian Amazonia

Owls are a poorly-studied avian group, despite their well-established role in prey regulation and biological control. For Neotropical species, distribution and abundance are especially poorly known. Structural components of forests have been used to explain patterns of owl habitat use and community structure, but such analyses have largely focused on species in the northern hemisphere. The present study examines whether components of forest structure influence habitat use (occurrence and abundance) for six species of owls in an upland forest in central Amazonian Brazil. Between October and November 2012, a playback method was used to sample occurrence and abundance in 30 points, each separated from the next by 1 km. Multiple linear regression analysis revealed relationships between four owl species and components of forest structure associated with food availability: Amazonian Pygmy Owl (Glaucidium hardyi) and distance to nearest stream (p = 0.023), Northern Tawny-bellied Screech Owl (Megascops watsonii) and leaf-litter depth (p = 0.045), Crested Owl (Lophostrix cristata) and dead fallen trunks on forest floor (p = 0.042), and Spectacled Owl (Pulsatrix perspicillata) and dead fallen trunks on forest floor (p = 0.009). A multiple logistic regression also revealed a significant association (p = 0.050) between the Spectacled Owl and dead fallen trunks on forest floor. The influence of the components of forest structure differs between the species, demonstrating interspecific differences in micro-habitat use, and reflecting the importance of food resource availability in habitat choice. Accepted 12 December 2014. © 2014 The Neotropical Ornithological Society