The role of donor and receiver size in the response to public cues in Hart's rivulus, Anablepsoides hartii

Aquatic prey use chemical alarm cues as public information sources to optimize behavioural deci-sions. Recent studies suggest that the contextual value of these cues is shaped by their source, the size of the donor relative to the receiver, and the size of the receiver itself. Here, we exposed Hart's rivulus (Anablepsoides hartii) to conspecific or heterospecific alarm cues from donors that were either smaller or larger than the mean focal rivulus size. Smaller rivulus reduced forag-ing in response to conspecific and heterospecific cues, regardless of donor size. However, larger rivulus exhibited no reduction in foraging towards small conspecific cues and increased foraging towards small heterospecific cues. Additionally, while conspecific donors elicited strong predator avoidance, rivulus exhibited stronger responses to large vs. small heterospecific cues. Our results demonstrate that the value of alarm cues is shaped by the interacting effects of receiver size and the size and species of cue donors.