Environmental drivers of calling activity in the critically endangered Lemur Leaf frog, Agalychnis lemur (Hylidae:Phyllomedusinae)

Abstract

Tropical frog species are known to exhibit high sensitivity to weather regime alterations, which leaves them vulnerable to ongoing climate change. This challenge is exacerbated by limited knowledge of species-specific responses to environmental change. We integrated passive acoustic monitoring and automatic signal detection to investigate the environmental underpinnings of calling activity of the critically endangered Lemur Leaf frog, Agalychnis lemur. We combined template-based detection with machine learning mitigation of false positives to infer the calling activity of a Lemur Leaf frog population across 18 months. We used directed acyclic graphs (DAGs) to determine the covariates needed to infer causal relations between environmental variables and calling activity. Our findings revealed that daily temperature has a strong direct positive effect on calling activity, with additional indirect effects mediated by relative humidity. Moreover, higher activity of the Lemur Leaf frog was triggered by increasing humidity independent of temperature, higher accumulated rainfall within the preceding 24 hours, and decreases in moonlight. This study provides insights into the complex interplay of environmental factors for determining calling activity in frogs. Our findings underscore the potential of passive acoustic monitoring for elucidating frog population activity and its responses to environmental changes, which can be valuable for understudied species in the context of climate change.

Marcelo Araya-Salas

Research Associate

My research interests include evolutionary behavioral ecology, cultural evolution, scientific programming and all possible combinations of them.