Trophic ecology of Geranoaetus polyosoma and Tyto furcata in an Atacama Desert agricultural landscape

The diets of the variable hawk (Geranoaetus polyosoma) and the barn owl (Tyto furcata) have been previously reported for the Atacama Desert of northern Chile. However, their ecological interactions and their role in the control of invasive species are unknown. In this work, the diet and competitive interaction of both raptors in an agricultural landscape were evaluated. Both species consume a high proportion of rodents (26.3% and 63.3% respectively), particularly Rattus sp. (20.8% and 30.0% respectively), which represent the highest contribution to the biomass consumed (67.9% and 60.2% respectively). Geranoaetus polyosoma consumes reptiles such as Microlophus yanezi (11.7%) and invertebrates (42.7%), mainly Coleoptera (30.7%) and Decapoda (7.11%). On the other hand, Tyto furcata consumed native rodents as Oligoryzomys flavescens (7.13%) and Auliscomys boliviensis (6.22%) and marine birds nesting in the desert, as Oceanodroma markhami (0.55%). Both raptors hunt over wide geographic ranges from the coast to the highlands, in wetlands, agricultural and desert areas. Despite sharing 44% of the prey consumed, there is only moderate interspecific competition. We discuss the possible role of both raptors as controllers of the exotic invasive Rattus sp.