Latitude and feeding behavior affect persistent organic pollutant concentrations in Andean condors

Persistent organic pollutants (POPs) are known to pose significant risks to humans, wildlife, and ecosystem health. Due to their persistence and lipophilicity, POPs bioaccumulate and biomagnify, primarily affecting the health of top predators and scavengers. As a long-lived scavenger, the Andean condor (Vultur gryphus) is particularly vulnerable to pollutants exposure, yet studies on POPs in this threatened species are scarce. Both environmental conditions and foraging habits can influence pollutant exposure and potentially affect the health of individuals and populations. In this study, we assessed the concentrations of POPs in Andean condor feathers across age classes along 2500 km in Chile. We also analyzed carbon (δ¹³C) and nitrogen (δ¹⁵N) stable isotopes to evaluate the association between food sources and pollutant burdens. Our findings revealed higher relative contributions of PCBs (35%) and PBDEs (32%), followed by DDTs (28%), and HCB (5%). Feather concentrations exhibited distinct geographic patterns of exposure, with high PBDE levels in industrialized areas, HCB in pristine regions, and overall higher POP concentrations in adults. Furthermore, feathers with high δ¹³C values -indicative of anthropogenic food sources (e.g. farming and landfills)- were positively associated with concentrations of all POP families. These exposure patterns likely reflect a combination of long-range atmospheric transport in remote zones and local pollutant emissions in anthropized areas, further shaped by dietary differences. We also detected an age-related increase in POP concentrations, consistent with bioaccumulation in this long-lived species. Overall, POP concentrations in condor feathers were in the lower level of reported values for raptors worldwide, likely reflecting variation factors such as species-specific physiology, feeding ecology, feather type, geographic zone, regulation actions, among others. Latitude, feeding habits, and age emerged as key determinants of POP exposure in this iconic scavenger. Despite being banned for decades, these contaminants remain present, and their toxicological implications for condors cannot be inferred from exposure data alone. This highlights the need for monitoring POPs and future studies integrating effect-based biomarkers to evaluate potential health consequences in condor populations.