Negligible hormonal response following dehorning in free-ranging white rhinoceros (Ceratotherium simum)

Abstract

The white rhinoceros (Ceratotherium simum) is experiencing unsustainable poaching losses fuelled by a demand for horn. Increasingly, private and state reserves are dehorning their rhinoceros populations in an attempt to reduce poaching pressure. Rhinoceroses use their horns in social interactions as well as during resource access and so its partial removal as part of reserve management practices may adversely influence these behaviours. Physiological stress can correlate with animal welfare, reproductive state and health and thus acts as a useful indicator of these parameters. To establish whether dehorning causes a physiological stress response, glucocorticoid and gonadal steroid profiles of free-ranging white rhinoceroses were determined through the collection and analysis of faecal steroid metabolites before and after dehorning. Faecal corticoid profiles were not influenced by the number of occasions a rhinoceros had been dehorned or by the number of days that had elapsed since dehorning. Furthermore, there was no apparent suppression in the concentrations of testosterone or progesterone metabolites in males and females, respectively, after exposure to multiple dehorning procedures. These findings should increase wildlife managers’ confidence that dehorning does not negatively impact white rhinoceros physiology as measured hormonally.

Factors affecting the behavior of captive white rhinoceros (Ceratotherium simum) and the accuracy of ad‐hoc keeper data

“…However, it is recommended that rhino are monitored if there are multiple consecutive high-visitor days to ensure that increased vigilance behavior are not associated with physiological effects such as elevated stress hormones. Such responses have been observed previously for rhino in stressful situations in the wild (Penny et al, 2020) and for other pachyderms in captivity (Grand et al, 2012).…”

Effects of dehorning on population productivity in four Namibia sub-populations of black rhinoceros (Diceros bicornis bicornis)

“…Dehorning may also have an indirect stress effect through disturbance caused by the interventions required for dehorning, including vehicles, helicopters, and capture teams. The potential effects of dehorning have been investigated, with studies reporting its impact on a range of factors including calf survival (Berger and Cunningham 1994;Atkinson 1996;Du Toit and Anderson 2013), inter-calving interval (ICI) (Alibhai et al 2001;Atkinson et al 2002;Du Toit 2001;Penny et al 2020a), and corticosteroid levels (Badenhorst et al 2016;Penny et al 2020b). Dehorning was found to have no significant long-term effect on corticosteroid levels in two studies on white rhinos (Badenhorst et al 2016;Penny et al 2020b).…”

No evidence that horn trimming affects white rhinoceros horn use during comfort behaviour and resource access

“…In contrast, du Toit and Anderson, (2013) reported that the dehorning of black rhinos did not affect the spatial locations of monitored individuals, finding no evidence of increased displacement. Recent research into the effects of dehorning in white rhinos found no evidence that the procedure influenced the duration of intercalf intervals or caused a long-term physiological stress response (Penny et al, 2020a(Penny et al, , 2020b. However, findings by Kretzschmar et al (2020) on the indicators of reproductive success in horned white rhinos was contradictory, identifying a strong positive correlation between horn size and the number of calves sired in one group of males but a negative correlation within another.…”