Prey often assess predation risk using multiple sources of information that differ in immediacy and reliability. How prey differentially weight direct predator-associated cues and heterospecific alarm cues remains a central question in behavioral ecology. To investigate this, playback experiments were conducted on free-ranging, predator-experienced Southern giraffes (Giraffa giraffa), using lion (Panthera leo) vocalizations and red-billed oxpecker (Buphagus erythrorhynchus) alarm calls presented in different positions within sequential playback trials. Lion vocalizations consistently elicited strong vigilance responses regardless of playback presentation order, indicating that giraffes assigned greater behavioral weight to direct predator-associated information. Giraffes also responded to oxpecker alarm calls, although responses were generally weaker and more variable than responses to lion vocalizations, suggesting that indirect heterospecific cues were weighted less strongly than direct predator cues. Evidence that preceding playback exposure strongly influenced subsequent vigilance responses was limited, as lion vocalizations continued to elicit stronger responses than oxpecker alarm calls across successive playbacks. Females additionally exhibited generally stronger vigilance responses than males across playback conditions. Together, these findings suggest that giraffes differentially weight multiple sources of risk-related acoustic information during antipredator responses.

IntroductionPredator recognition is essential for prey survival, yet, whether responses are shaped by evolutionary predispositions or by ecological experience remains debated.MethodsWe tested vigilance responses of fifty-one free-ranging Southern giraffes (Giraffa giraffa) to controlled playbacks of lion roar-grunt sequences in two South African populations: a predator-naïve population in a reserve without lions and a predator-experienced population in a reserve where lions were reintroduced five years ago.ResultsBoth populations oriented rapidly to lion calls, suggesting that acoustic features of lion vocalizations act as generalized danger cues. However, predator-experienced giraffes sustained vigilance ten times longer (mean ± SD: 513.34 ± 421.34 s, N = 24) compared to predator-naïve giraffes (49.06 ± 46.26 s, N = 27). Vigilance responses during lion playbacks, in general, were higher in the predator-experienced population, whereas responses to control calls did not differ between sites.DiscussionThese findings indicate that while immediate orientation likely reflects evolved sensitivity to acoustically harsh predator cues, the persistence of vigilance is shaped by ecological experience. Our study demonstrates that predator reintroduction can rapidly recalibrate prey risk perception, highlighting the dynamic interplay between evolved predispositions and learning in shaping antipredator responses.