Fragment size and isolation is associated with the presence of two forest owls in a fragmented environment in Central Argentina

Abstract

In the semiarid Espinal ecoregion from central Argentina, deforestation has produced a large retraction of native forests and an accelerated process of fragmentation. Here we assess the effects of forest fragmentation within an agricultural matrix on the presence of two forest owls: the Ferruginous pygmy-owl (Glaucidium brasilianum) and the Tropical screech-owl (Megascops choliba). We searched for the species in fragments of different sizes and at different distances from large-continuous forest tracts. We detected one or both species at 43% of the 84 surveyed points. The Tropical Screech Owl was detected at 13 points, the Ferruginous Pygmy Owl was detected at 14 points, and both species were detected at 9 points. For the Ferruginous pygmy-owl, the area of the fragment where the point registration was made was the only variable associated with its presence. The model for Tropical Screech-Owl indicated that the variable that best explained its presence was the distance to the nearest forest fragment. For both species the association was negative. Our results suggest that despite being generalist and widely distributed species, both owls were negatively affected by the fragmentation process, highlighting the importance of the preservation of forest remnants and their connectivity.