Are good fighters also good singers? The relationship between acoustic traits and fight success in the treefrog Pithecopus nordestinus (Phyllomedusidae)

Abstract

Morphological characteristics are known to be important predictors of victory in aggressive disputes in the animal world. Among anurans, however, acoustic communication also plays an important role in intrasex conflicts. Although there is evidence for the influence of spectral parameters of calls (e.g., fundamental and dominant frequencies) in anuran disputes, the role that temporal parameters (e.g., duration and repetition rate) play in success during physical conflicts is still poorly understood. We describe the behavior of male frogs in agonistic interactions and investigate the functions of the different types of calls emitted in different social contexts. We also evaluate how body characteristics (mass and body size) and bioacoustic characteristics (repetition rate of the calls) influence success in physical conflicts of Pithecopus nordestinus (Anura: Phyllomedusidae). Agonistic disputes involved gradation in the emission of calls, visual displays, and physical clashes. The fighting call increased in proportion during clashes, indicating a function associated with aggression/intimidation. The uneasiness call (new subcategory herein defined) was only performed by losers during physical clashes, suggesting a meaning of submission or restlessness. No differences were found in any of the morphological parameters between winners and losers of physical disputes. On the other hand, the repetition rate of the aggressive call was positively related to success in fights and proved to be a good predictor of success in fights between males of P. nordestinus. Our results contribute to understanding the influence of temporal parameters of calls on success in physical disputes of this Neotropical treefrog.