Calling amplitude flexibility and acoustic spacing in the territorial frog Allobates femoralis

Abstract

Most male frogs produce calls to attract females and repel rivals. The transmission of these calls can be affected by many acoustic and environmental characteristics, which can influence the detection and decoding of the signal by the receiver. Calling-perch height has a strong influence on sound propagation and acoustic spacing with neighboring males, but how frogs optimize their calling behavior in this context is poorly understood. In this study, we investigated if and how frogs can adjust the calling energy in the context of acoustic spacing. Our aim was to evaluate the relationship between calling-perch height, nearest-neighbor distance, and sound-pressure level in the brilliant-thighed poison frog Allobates femoralis. We found that frogs flexibly adjust the calling amplitude according to the calling-perch height without affecting the effectiveness signal propagation. Accompanying signal propagation experiments demonstrated that calls produced with lower amplitude from higher perches propagate similar to louder calls from the ground. Our results suggest an adjustment to the hypothesis of a general positive effect of calling-perch height on signal effectiveness, where highly territorial frogs adjust their calling behavior to reduce energy expenditure and optimize acoustic communication with conspecifics. Significance statement In acoustically communicating species, sound propagates better when broadcasted from elevated positions. However, callers may adjust their calling behavior to optimize the sound transmission under ecological constraints. By using a correlative and manipulative approach, we show in a poison frog model that males can adjust their calling amplitude according to the calling-perch height. We then discuss that this calling adjustment optimizes the acoustic spacing between conspecific males and reduces energy consumption.

Regardless of personality, males show similar levels of plasticity in territory defense in a Neotropical poison frog

“…Specifically, the personality trait aggressiveness can be seen as a latent variable that can be derived from the covariance between the latency to turn and jump towards an intruder and the speed to approach the intruder 30 . Like in many frogs, A. femoralis call peak frequency 32 , but not sound pressure level 33 , is negatively correlated with, and therefore indicates, body size.…”

Reproductive behaviors promote ecological and phenotypic sexual differentiation in the critically endangered Lehmann’s poison frog

“…This differential habitat use may be associated with territorial behavior, whereby males call from elevated perches to announce their presence to male conspecifics and to attract females (Pröhl 2005). Calling-perch height has a positive influence on sound propagation (Rodríguez et al 2020), as calling from higher perches allows the signal to propagate over larger distances increasing the probability of the stimulus reaching potential receivers (Brenowitz et al 1984;Kime et al 2000;Parris 2002;Schwartz et al 2016). Also, in some anuran species, perch height is directly related to mating success (Greer and Wells 1980;Pröhl and Hödl 1999).…”

Androgen responsiveness to simulated territorial intrusions inAllobates femoralismales: evidence supporting the challenge hypothesis in a territorial frog

“…Allobates femoralis males use advertisement calls to engage in social interactions with conspecifics (e.g. territory tenancy advertisement, inter-male spacing, courtship; Ringler et al, 2017; Rodríguez et al, 2020; Stückler et al, 2019). Interestingly, vocal behaviour was not dependent on androgen levels in A. femoralis males.…”

“…In this study, we tested the effect of territorial challenges on the behavioural and androgenic response of the Brilliant-thighed poison frog, Allobates femoralis . This species has become a model system for the study of acoustic communication (Amézquita et al, 2006, 2005; Gasser et al, 2009; Rodríguez and Hödl, 2020), spatial navigation (Pašukonis et al, 2016, 2014a, 2014b, 2013) reproductive (Ringler et al, 2018; Stückler et al, 2019; Ursprung et al, 2011) and social behaviour (Narins et al, 2003; Ringler et al, 2017; Rodríguez et al, 2020; Tumulty et al, 2018) in poison frogs. Males vocally advertise and actively defend their territories to conspecific males (Hödl, 1983; Narins et al, 2003; Ringler et al, 2011; Roithmair, 1992).…”