Escape Response of Tadpoles of Two Species of Bokermannohyla (Anura, Hylidae) to Simulated Threat

We investigated how tadpoles of Bokermannohyla martinsi (Martin's Treefrog) and Bokermannohyla nanuzae (Jaboticatubas Treefrog) respond to a simulated predator attack. We tested whether escape variables (depths of microhabitats used, promptness to react, and distance covered while fleeing) varied throughout the year, depended on tadpole size, or both. We expected these variables to be relatively constant throughout the year and that smaller individuals would react more promptly to the stimulus, as they are likely more vulnerable to a broader set of predators. We compared depths used by tadpoles before and after fleeing and expected them to move to deeper microhabitats if depth confers extra protection. We also expected tadpoles positioned at deeper microhabitats to take longer to react and to move less. When comparing the two species, we expected the tadpoles of B. nanuzae, which are potentially cryptic to predators, to take longer to react and to flee shorter distances. We also recorded and compared types of stream substrates used before and after escape by each species and compared the two species regarding microhabitat (bottom type and depth) use. Microhabitat preferences differed between species, but microhabitat types were used in the same proportion before and after fleeing by both species. They showed similarity in promptness to react and distance covered while fleeing from a threat, suggesting that their different coloration does not lead to differentiation in these variables.