Not all xenarthrans are eaten equally: In savannas, harpy eagles favor armadillos, and their prey show taphonomic signatures similar to those in Amazonia

Abstract

The harpy eagle (Harpia harpyja) is a top predator inhabiting lowland tropical forests from southern Mexico to northern Argentina. In eastern and southeastern Brazil, its populations are declining due to habitat loss and hunting. While the species' diet is well-documented in rainforests, in non-forested habitats it remains poorly understood. In this study, we analyze diet composition and taphonomic patterns of harpy eagle prey in an ecotone between the Cerrado and Amazonia ecoregions in central Brazil—an atypical habitat for the species. Using osteological material, camera trap data, and molecular analyses, we identified prey remains and assessed bone damage patterns. Our findings reveal that the harpy eagle's diet in this region differs from previous studies in tropical forests. We identified 42 individuals of seven prey species, with armadillos dominating the diet, contributing 88.2 % of the total biomass, being 74 % Cabassous squamicaudis and 11 % Euphractus sexcinctus. Additionally, molecular analyses confirmed predation on a brocket deer, an unusual record of harpy eagles preying on terrestrial ungulates. Taphonomic analysis revealed that most crania and synsacral elements showed minor damage or only a few missing bones, suggesting prey-specific processing behaviors. These findings provide new insights into the harpy eagle's dietary flexibility and behavioral adaptations in non-forest environments. Our study highlights the importance of habitat-specific diet research for conservation planning and species management, particularly in regions undergoing rapid habitat loss.