Non-ingested vertebrate prey remains accumulated by the Chaco eagle (Buteogallus coronatus): neo-taphonomy to evaluate open-air faunal records in central western Argentina

Abstract

The Chaco eagle (Buteogallus coronatus) is a large, endangered, and little-known bird of prey distributed throughout southern South America. This bird of prey accumulates large amounts of prey remains around its nests in open landscapes. To present a reliable pattern to distinguish the action of the Chaco Eagle as a potential accumulator of faunal remains in open-air archaeological contexts, we conducted a neo-taphonomic study in an area of the eastern plains of the CWA, analyzing modern remains accumulated around a nest of the Chaco eagle. Our taxonomic analysis allowed us to identify the presence of different taxa belonging to two classes: mammals and reptiles. Most of the specimens identified were non-ingested remains. The armadillo Zaedyus pichiy was the most conspicuous prey species, represented by osteoderms and skulls. We registered several endoskeletal remains and osteoderms of the Chaco tortoise (Chelonoidis chilensis), as well as bone and tooth remains of two little-known and reported species in the study area: the red tegu (Salvator rufescens) and the Patagonian weasel (Lyncodon patagonicus). In addition, we found remains corresponding to two species of small-sized rodents. We also discovered strongly digested vertebrae of an indeterminate small Ophidia preserved in the only recovered pellet. The proportion of weathering was high, with stages 1 and 2 identified as the most dominant degrees. Notably, specimens with two stages of weathering were detected based on the side grounded to the floor. The proportions of breakage, on the other hand, were low. We hope this work contributes to the distinction of accumulating agents in the region's archaeological sites, especially considering the high importance that armadillos have had for the past human populations of the area.