Drivers of geophagy of large-bodied amazonian herbivorous and frugivorous mammals

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Mineral licks, critical for the survival of many large-bodied mammals in the Amazon, serve as keystone resources that influence the behavior and ecological dynamics of these species. This study presents the most comprehensive analysis to date on the drivers of geophagy—the consumption of soil by animals—at mineral licks in the Peruvian Amazon. Using a combination of camera traps and soil analyses from 52 mineral licks, we examined the visitation patterns of six large-bodied mammals: the black agouti (Dasyprocta fuliginosa), paca (Cuniculus paca), collared peccary (Pecari tajacu), Brazilian porcupine (Coendou prehensilis), lowland tapir (Tapirus terrestris), and red howler monkey (Alouatta seniculus). Our results reveal that mineral licks provide essential nutrients, particularly sodium (Na), which may be deficient in the diets of frugivorous species such as agouti, paca, and red howler monkey, supporting the mineral supplementation hypothesis. Conversely, the toxin adsorption hypothesis, which posits that animals consume soil to mitigate dietary toxins, was most strongly supported for the herbivorous Brazilian porcupine. The omnivorous collared peccary and the mixed-diet tapir exhibited complex interactions between soil characteristics, suggesting that both mineral supplementation and toxin adsorption play roles in their geophagy. This study highlights the importance of mineral licks for the conservation of Amazonian mammals, emphasizing their role in supporting biodiversity by providing critical nutritional resources that enhance species fitness and ecological resilience. Our findings underscore the need for the protection of these sites, which are integral not only to the survival of individual species but also to the health of the broader Amazonian ecosystem.