MONITORAMENTO TÉRMICO DE BAT CAVES NA FLORESTA NACIONAL DE CARAJÁS

THERMAL MONITORING OF BAT CAVES IN THE CARAJÁS NATIONAL FOREST

Abstract

Shelters with exceptional bat populations are called bat caves. Monitoring this type of shelter can be challenging, given the locations and conditions of these environments. However, monitoring the temperature of these caves has been pointed out as a proxy for how bats are using these environments. Here the results of a detailed thermal monitoring of two bat caves in the Carajás National Forest are presented, accompanied by estimates of the resident bat populations in these caves. Additionally, a description of the daily patterns of bats leaving and returning to these shelters, identification of possible seasonal patterns in the fluctuation of the resident bat population in these caves and identification of the physical and thermal characteristics preferred by the bats. This thermal monitoring showed that the internal temperatures of these caves are quite high in relation to the external temperatures, and are more associated with the presence of large colonies of bats of the Pteronotus genus. Furthermore, a dynamism in these environments was observed, caused by the movement of bats between shelters and marked variations in population size at different times. The dynamic nature observed reinforces the need for continuous, long-term monitoring in order to better understand these shelters and their ecological relationships. Short, sporadic inventories in these environments will inevitably lead to erroneous conclusions, with serious ecological, conservation and licensing implications. As such, bat caves need special monitoring in relation to the use and pressures they experience, especially in the face of the changes and attempts to make Brazilian speleological legislation more flexible.