Acoustic Localisation as a Tool to Aid Monitoring of Golden Jackals (Canis aureus).

Abstract

Golden jackals (Canis aureus) have rapidly expanded their range across Europe, raising ecological and socioeconomic concerns. As a highly vocal species, jackals can be monitored using howl surveys or passive acoustic monitoring (PAM) to estimate population sizes and habitat preferences. A recent advancement in PAM is acoustic localisation, which estimates the source of sounds by measuring the time differences of their arrival at multiple synchronised recorders. This technique can improve the accuracy of population and density estimates by more precisely calculating distances between vocalising animals and recorders. However, GPS-synchronised acoustic recorders are costly, which limits their broader use. In this study, we tested the efficacy of a low-cost recorder, the CARACAL, for acoustic localisation of golden jackals. We deployed 10 CARACALs over a 10 km2 area of the Lunca Mureşului Natural Park, Romania, for seven nights. Alongside passively recording jackal howls, we also conducted howl surveys. We recorded jackal howls every night of the survey and successfully localised 27 jackal and 16 human howls, with human howls localised to within an average of 41 m of their actual location. The average distance between the recorders and estimated positions of vocalising jackals was just under 1 km, with howls detected from as far as 2.5 km away. However, some jackal howls were not detected clearly, or at all, on active recorders that were as little as 0.9 km away. Based on these results, we recommend a conservative spacing of 0.8-1 km between recorders in future deployments, though this will depend on local environmental conditions. Overall, this study highlights acoustic localisation as a valuable tool for improving monitoring efforts and gathering more detailed data on jackal ecology. This information could significantly contribute to understanding their expanding range across Europe while informing the development of effective monitoring and management strategies for golden jackals.