Natural licks are activity hotspots for frugivorous bats in the Peruvian Amazon. Large numbers of frugivorous bats congregate at licks to drink water. Because most Amazonian soils are relatively poor in nutrients, plants may contain low concentrations of some nutrients; consequently, frugivorous bats may face nutrient limitations. Accordingly, a potential explanation for lick visitation by bats is to obtain key limited resources. We assessed this hypothesis by comparing concentrations of cations (Ca, K, Mg, Na) in water at three licks and associated non-lick sites across years and seasons at Los Amigos Conservation Concession in south-eastern Peru. We also examined bat activity patterns between lick and non-lick sites. Regardless of the season, at licks >10 bats per net h1 were captured compared with forest and gap sites where <1 bat per net h1 was captured. At licks bats belonged primarily to the subfamily Stenodermatinae and over 70% were reproductive females. Although calcium, magnesium and potassium concentrations varied across water sources, sodium concentrations were consistently higher in lick water (>50 ppm) compared with creeks and oxbow lakes (<2 ppm) across seasons. Therefore, since sodium is one of the most limiting nutrients for vertebrates in the tropics, licks may function as sources of sodium (or other elements) for bats. In any case, licks are reliable potential sources of sodium in the south-eastern Peruvian Amazon, an otherwise mineral-poor landscape. Copyright © 2010 Cambridge University Press.