The ontogeny of decision-making in an eavesdropping predator

Predators use prey-emitted cues to assess and localize potential food sources. Sexual advertisement calls offer conspicuous cues for eavesdropping predators. While the ontogeny of predatory behaviour is key for survival and can determine adult responses, our understanding of the development of the responses to prey-emitted cues is limited. Here, we measured the responses of juvenile and adult fringe-lipped bats (Trachops cirrhosus) to the acoustic advertisement calls of co-occurring anurans. We confirmed that adult bats modulate their foraging behaviour based on their prey's acoustic cues associated with prey palatability. The responses of juvenile bats revealed that ontogeny plays an important role in bat predatory responses. In contrast to adults, prey palatability did not predict predatory behaviour in juveniles, which responded strongly to poisonous toads and little to some palatable frog species, suggesting that avoidance of poisonous species is learned through experience. Despite these differences, both juveniles and adults appeared to attend to acoustic cues related to body size. Our results support the hypothesis that, over development, acoustic preferences of eavesdropping predators become more closely aligned with advantageous foraging outcomes. Overall, these results offer the first evidence of developmental changes refining decision-making in an eavesdropping predator in the wild.