Dehorned rhinos less social
According to data from a Swiss research team, dehorned black rhinos reduce both their range and their willingness to interact socially. Nevertheless, dehorning remains important for protection against poaching.
Dehorning endangered black rhinos to protect them from poachers could have a bigger impact on their behaviour and social life than previously thought.This according to a study published in the science journal PNAS in July. The researchers say that, after dehorning, a rhino's range shrinks by an average of 45% and their social interactions decrease by an average of 37%. Bulls in particular are less likely to interact with other males.
The study was conducted by scientists from the University of Neuchâtel in Switzerland, who analyzed data from 4 760 sightings of 368 black rhinos between 2005 and 2020 in ten reserves in northeastern South Africa.
"It's like they feel less safe and vulnerable without the horn. Being generally solitary, they are unaware that their neighbours are also dehorned. They explore less and retreat to more central parts of their range," explains lead author Vanessa Duthé, a PhD student at the University of Neuchâtel, as reported by Nature magazine, citing PNAS.
According to Duthé, maps of rhino movements clearly show how range size depends on whether an animal bears a horn. The range of dehorned animals shrank by an average of 11.7 km² (45.5%). The home range of dehorned females was on average 15.42 km² (53.08%) smaller, than that of dehorned males 9.13 km² (or 38.03%).
However, it remains unclear how this affects the social structure of the species and gene flow. "Our results show the importance of considering animal behavioural responses when weighing the net benefits of conservation measures," Duthé said.
According to co-author Rickert van der Westhuizen of the South African environmental agency Ezemvelo KZN Wildlife, there will always have to be a trade-off between benefits and costs. “These and other studies show that the effects of dehorning are not severe enough to stop. As long as such interventions do not lead to the loss of rhinos or a decrease in the productivity of the population, they are worth every penny," he said.