Chemical cues of conspecific predation elicit distinct behavioural responses in cannibalistic poison frog tadpoles

In cannibalistic species, conspecifics can be both predators and prey. As a result, conspecifics present a unique conflict at the intersection of predation, competition and nutritional resources in these species. To better understand how individuals respond to the complex information of conspecific chemical cues, we studied aggressive and cannibalistic tadpoles of the dyeing poison frog, Dendrobates tinctorius. We used a standardized open field test to compare behavioural responses to a positive cue (food), a negative cue (predator) and two conflicting cues (conspecific density and injured conspecifics). We specifically used chemical cues to understand how individuals respond in the absence of additional information that would disambiguate their status as conspecific predator versus prey. We found that the injured conspecific cue elicited a response distinct from either the food cue or the predator cue: tadpoles explored more relative to baseline and predator cues but spent less time moving compared to the food cue. We suggest that these patterns reflect cue-dependent behavioural strategies that maximize exploration while minimizing detection in the presence of conspecific cannibals. In addition to cue-specific changes in behaviour, we observed consistent differences in individuals' behaviour across environments and found that activity and exploratory behaviour were positively correlated across environments. Taken together, our results demonstrate that conspecific cues are interpreted as distinct from either food cues or predator cues in a cannibalistic species where they can represent both.