Screaming calls of Leptodactylus savagei (Smoky Jungle Frog) function as an alarm for conspecifics

Neotropical frogs in the family Leptodactylidae frequently emit a loud scream upon being captured by predators, and the leptodactylid scream call was first classified as a distress call functioning to startle would-be predators into releasing prey frogs. However, other authors have suggested that scream calls function to warn nearby conspecifics of a predator threat (i.e., an alarm call) and/or to attract larger secondary predators to distract or predate the primary predator. In this study, we used a repeated-measures playback experiment to test whether Leptodactylus savagei (Smoky Jungle Frog) in Costa Rica responds to scream calls in ways consistent with it functioning as an alarm call. If scream calls emitted by individuals during predation events also serve to warn nearby conspecifics of a predator threat, we predicted that scream calls would elicit elevated flight responses compared to when advertisement calls or control grey-noise treatments. We observed five primary behavioral responses: individuals flattened their bodies, faced their dens, fled into the dens, faced the audio treatment, and called back with a territorial vocalization. We found that behavioral responses differed by treatment: scream calls elicited a greater proportion of flight responses, whereas advertisement calls appeared to cause individuals to demonstrate more interest in the call (particularly females). Our results suggest that L. savagei respond to screaming calls from conspecifics by fleeing in ways consistent with the call functioning as an alarm. Future studies are needed to test whether scream calls also function as a distress call and/or attract secondary predators.