Fidelity in the use of iron caves by Bokermannohyla martinsi (Anura: Hylidae): a step further in unveiling the importance of Brazilian caves for the herpetofauna

Abstract

Bokermannohyla martinsi is an endemic anuran from the mountains of the southernmost portion of the Espinhaço range in southeastern Brazil. This region is known as the Iron Quadrangle (Quadrilátero Ferrífero) due to its ironrich outcrops and is under intensive mining exploration, which threatens its caves. Here, we investigated whether males, females, and juveniles of B. martinsi use iron caves throughout the year, exhibit cave fidelity, distribute themselves differently within caves, and prefer to use caves that are microclimatically stable. We sampled 10 caves during eight 15-day periods regularly spaced throughout one year. Frogs used caves throughout the year and exhibited cave fidelity. They preferred the dysphotic zone, and young individuals remained closer to the entrance of the cave and to the ground, maybe due to their lower locomotory/climbing ability compared to adult frogs. Bokermannohyla martinsi preferred more stable caves (those with lower temperature and humidity variation), and the use of caves by females was more intensive during the dry and cold season, which may be related to their shorter permanence at breeding sites (streams). Our results show that caves are important habitats for B. martinsi, as it may be the case with other species, too, and their destruction should thus be evaluated and weighted with greater care when planning their mining.