Dehorning impacts white rhinoceros behaviour less than social events: evidence from Botswana

Abstract

Dehorning is a conservation measure used to protect rhinoceroses (‘rhinos’) from being poached by removing most of the visible horn and thus reducing the monetary reward for the risk that a poacher takes. Rhinos use their horns in comfort and aggressive social behaviours. The loss of the horn might result in a decrease in aggressive and affiliative behaviours and an increase in avoidance behaviours after dehorning due to a reduced effectiveness and potential discomfort when using the nasal body part. The dehorning procedure, which includes chasing and immobilization, can lead to the separation of groups and might therefore result in fewer social interactions. To estimate whether the stress of the dehorning procedure and the loss of the horn affect the activity budget of the rhino, we compared general activities and horn-related behaviours before and after dehorning. We observed nine (six females and three males) wild white rhinos (Ceratotherium simum simum) in Botswana for 1 month before and 1 month after dehorning. The proportions of feeding, resting, comfort, aggressive, avoidance and affiliative behaviours did not change significantly within 1 month after dehorning. We observed sex-specific changes in proportions of locomotion and in vocalization rates, which we linked to the chasing during the procedure and to the social events of two births in the study population. Effects of the dehorning itself seemed to be weak and short-lived. Our results suggest that dehorning has no major impact on rhino behaviour. However, there is a key need to investigate the effectiveness of dehorning in reducing poaching events.