Collpas as activity hotspots for frugivorous bats (Stenodermatinae) in the Peruvian Amazon: underlying mechanisms and conservation implications

In western Amazonia, large numbers of frugivorous bats regularly visit natural forest clearings known locally as collpas (also called clay licks or mineral licks). Bats arrive at collpas to drink water that has accumulated in depressions created by larger mammals that consume soil. Although collpa visitation by bats appears relatively common in western Amazonia, little is known about its causes and its ecological implications. In this dissertation I describe general and seasonal patterns of collpa visitation by frugivorous bats in the Peruvian Amazon, and I investigate potential explanations for this unique behavior. Regardless of season, collpas seem to be activity hotspots for frugivorous bats, especially for reproductive females. Furthermore, collpas are visited almost exclusively by frugivorous species of the subfamily Stenodermatinae. Because some nutrients are found in low concentrations, a potential explanation for collpa visitation is to obtain key limited resources. Collpas are mineral-rich water sources. The content of selected minerals in collpa water, especially sodium, was significantly higher compared to other natural sources of water such as creeks, oxbow lakes, and rivers for both dry and rainy seasons. Thus, collpas may function as mineral sources for female reproductive frugivorous bats. Stenodermatine bats feed mostly on figs, whereas bats from the sub-family Carolliinae feed on Piper fruits, but also complement their diets with insects as well as other plant species. Thus, because stenodermatine species are extremely common at collpas, collpa visitation may be related to nutrient deficiencies in specific diets. Although there was a clear distinction in mineral and nitrogen content of Ficus and Piper fruits, they seem to provide frugivorous bats enough nitrogen (protein) and most minerals to meet their maintenance requirements. However, both fruit genera were very limited in sodium, which suggests sodium limitation for frugivorous bats in the southeastern Peruvian Amazon. Carolliine bats may be obtaining sodium from insects, whereas stenodermatine bats may use collpas as secondary sources of sodium, especially during reproduction. Additionally, I provide experimental evidence that demonstrates that stenodermatine bats have a strong preference for collpa water. Finally, because collpas are important mineral sources for frugivorous bats, they should be considered important conservation targets