Toxic towns: Drivers of anticoagulant rodenticide exposure in an urban edge carnivore

Anticoagulant rodenticides (ARs) are used globally to control rodent populations; however, exposure of non-target wildlife is a growing conservation concern. Generalist predators are particularly vulnerable to both lethal and sublethal effects of ARs via bioaccumulation. Caracals (Caracal caracal) in and around Cape Town are attracted to forage on the urban edge, where they face AR exposure risk. We use generalized linear models to investigate the liver concentration and diversity of ARs in 102 caracals within a global biodiversity hotspot. We assess sex and age relationships, as well as their association with habitat types and urban features to identify exposure routes and landscape drivers of risk. Exposure patterns follow global trends in carnivores, with high exposure (78%) and a median of three compounds detected per individual, suggesting repeated, long-term exposure. Highly toxic second-generation compounds dominated the exposure profile. AR burdens varied across the population, peaking in older individuals, likely due to bioaccumulation and multiple exposure events. Caracals using more vegetated, greener urban areas with urban amenities such as food service outlets were more likely to be exposed and have higher AR diversity and concentrations. The sublethal effects of ARs are currently unknown for caracals; however, subadult caracals in poorer condition exhibited higher total rodenticide loads. ARs present a cryptic threat to urban wildlife populations already vulnerable to increasing habitat loss and anthropogenic sources of mortality. This study supports global trends suggesting targeted mitigation should include policies that reduce AR use, particularly for rodent control and food waste management near wildlife habitat.