Suitability of acoustics as non-lethal deterrents for macropodids: the influence of origin, delivery and anti-predator behaviour

Context Auditory devices used to deter wildlife are a potentially humane and effective way of minimising deleterious interactions with humans and their livelihoods and have been used successfully for many species around the world. Acoustic cues can be used to manipulate anti-predator behaviour, encouraging animals to forage elsewhere. Employing acoustics derived from natural sources to make use of innate behavioural responses has been suggested to outperform novel or artificial sounds; however, anti-predator strategies vary among sympatric species and will influence the utility of acoustic stimuli for deterring wildlife. Aims We aimed to test the interaction between the source of origin (natural or novel) and species traits (anti-predator strategy – grouping behaviour) on the efficacy of using acoustic stimuli to elicit alarm responses for two species in the family Macropodidae commonly associated with browsing on forest plantation seedlings; the red-necked pademelon (Thylogale thetis) and the red-necked wallaby (Macropus rufogriseus banksianus). Methods We tested these factors in captivity using playback experiments of acoustic stimuli and monitored the behavioural responses of subjects. Results Red-necked pademelons exhibited strong responses to bioacoustic and novel stimuli but did not greatly differentiate among them. Short-term habituation to predator calls was detected whereas responsiveness to novel sounds increased. Red-necked wallabies most strongly responded to conspecific distress calls, showing no sign of short-term habituation. Conclusions Results from the present and other studies suggest that bioacoustic deterrents, particularly those utilising natural conspecific sounds, aimed at communicating danger, have the potential to play an important role in non-lethal wildlife management, although that responsiveness varies with the form of anti-predator strategies employed. Implications If alarm responses translate into subjects vacating targeted areas, then there is some potential to implement non-lethal acoustic deterrents for macropodids alongside other management measures aimed at preventing impacts on primary production. Problematically, our experiments showed that without accurate acoustic delivery, particularly of sounds with infrasonic components, the development of effective bioacoustic deterrents may remain stymied.