Frog distress calls may attract nearby animals during predation: an opportunistic observation involving a Vine Snake, a Blacksmith Treefrog, and marmosets

Abstract Distress calls are widespread among frogs, yet their communicative function remains poorly understood. Several hypotheses have been proposed, including startling predators, warning nearby individuals, and attracting other animals that may interfere with predation, but direct evidence supporting any of these functions is scarce. Here we report an opportunistic observation of a Blacksmith Treefrog ( Boana faber ) emitting distress calls while being attacked by a vine snake ( Chironius sp.) in the Brazilian Atlantic Forest. During the predation event, four hybrid marmosets ( Callithrix jacchus × C. penicillata ) approached the source of the calls, closely followed the snake, and physically interacted with it while the frog continued vocalizing. The marmosets became progressively more engaged as the frog increased the intensity and rate of distress calling, suggesting that the calls attracted their attention and may have contributed to their interference with the predator. Although the outcome of the predation attempt could not be determined, this observation suggests that frog distress calls may attract nearby animals to an ongoing predation event, potentially creating additional opportunities for escape. Further field observations and experimental studies are needed to determine how widespread this phenomenon is and whether it may have contributed to the evolution of distress calls in frogs.