Density and habitat use by owls in two Amazonian forest types

Abstract

We conducted a short-term study on density and habitat use in an Amazonian owl assemblage. The census was conducted in terra-firme forest and black-water flooded forest or igapó forest. Six owl species were recorded, the Tropical Screech-owl (Otus choliba), the Tawny-bellied Owl (O. watsonii), the Black-banded Owl (Strix huhula), the Spectacled Owl (Pulsatrix perspicillata), the Ferruginous Pygmy-owl (Glaucidium brasilianum), and the Stygian Owl (Asio stygius). The most abundant species was the Tawny-bellied Owl (0.42 individuals/ha) followed by the Spectacled Owl (0.31 individuals/ha). Some species showed clear tendencies to use different habitats. The Tawny-bellied Owl was more abundant in terra-firme forest, while its congener, the Tropical Screech-owl, was much more common in igapó forest. The Stygian Owl and the Ferruginous Pygmy-owl were also recorded exclusively in the igapó forest census. These results indicate that terra-firme forest and igapó forest supported distinct owl assemblages. Our work and other studies suggest regional variability in owl density in Amazonia.