Condition-dependent ways to manage acoustic signals under energetic constraint in a tree frog

Because resources needed to produce sexual displays are limited, courting males are expected to face trade-offs between investing in display properties selected by females and investing in the amount of display. This should be particularly the case in species with energetically expensive displays and high intrasexual competition through endurance rivalry like chorusing anurans. Studies that manipulated the energetic constraint in calling anurans have led to conflicting results, potentially due to nonsimultaneous assessment of call properties selected by females and the calling activity (i.e., the total number of calls emitted by a male), and/or to the use of different strategies to face display trade-offs by males. We investigated display trade-offs in 36 males Hyla arborea (L.) by manipulating their energetic constraint through starvation/feeding experiments while recording their overall call production during 10 consecutive nights. Even when considering simultaneously calling activity and call properties, the energetic constraint does not appear to impact call production. However, when focusing on individual responses, it appears that males cannot maintain both calling activity and within-bout call rate. Big and high-condition males mainly decrease this call property along the experiment, whereas small and low-condition males mainly decrease calling activity. Moreover, males who maintained calling activity the most are those who lost the most condition and, when refed, starved males only increased calling activity. These results suggest that calling activity is costlier to maintain than call properties but may confer a greater advantage in mating success, leading to different allocation strategies among males of different conditions.