According to a new study, the impact of poaching and intensive hunting on rhinos may have reduced the animals’ horns.
Through careful analysis of 135 years of photographs, a research team from the University of Cambridge found evidence that all rhino species – white, black, Indian, Java and Sumatra – saw the length of their horns decrease “so significant “over time.
The researchers said that due to the strict security protocols that prevent scientists from accessing real rhino horns for study, due to their enormous value, this is the first time that the length of the horn has been studied for a long period of time.
Rhino horns are exorbitantly priced, and although the animals are in serious danger of extinction, their horns, obtained from poaching, are in great demand both as a financial investment and for their use in traditional medicines in China and Vietnam.
But hunting has not only caused a sharp decline in rhino populations: the researchers suggest that decades of hunting for longer-horned rhinos have left more and more survivors with smaller horns, who have reproduced more and transmitted the their smaller traits to future generations.
Similar traits have been shown in other animals before, but never in rhinos.
“We were really excited to be able to find evidence from photographs that rhino horns have shortened over time. They are probably one of the hardest things to work on in natural history due to safety concerns, “said Oscar Wilson, a former researcher in the Department of Zoology at the University of Cambridge and first author of the report.
Wilson, who now works at the University of Helsinki, Finland, added: “Rhinos developed their horns for a reason – different species use them in different ways, for example to grab food or to defend against predators – so we think having smaller horns will be detrimental to their survival ”.
To conduct the horn size study, the researchers also measured other body parts on each rhino photograph, including the length of the body and head, so that the length of the horn could be accurately measured in proportion to the body size. .
In addition to photographs, the team examined drawings made over the past 500 years.
The researchers said they also saw a dramatic change in human perception of rhinos around 1950, when animals became the focus of conservation efforts rather than hunting.
“We have found that we can use images from the past few centuries to visualize how human attitudes towards wildlife have changed and how artists have influenced these views,” said Dr Ed Turner of the Cambridge Department of Zoology, senior author of the report.
Included in the collection are many hundreds of photographs showing rhinos killed by hunters, taken between the late 19th and early 20th centuries. These include a photograph of US President Theodore Roosevelt, taken in 1911, standing triumphant on a black rhino he had just killed.
Other early images show rhinos as huge and frightening animals chasing humans. The researchers said they believe the images helped justify hunting these animals.
“The images suggest that there was very little effort to promote the conservation of rhinos to the public before the 1950s. But after that the focus suddenly shifted from hunting the animals to trying to keep them alive,” they said.
This change coincided with the collapse of European empires as African countries became independent and European hunters no longer had easy access to Africa for hunting.
The research is published in the diary People and Nature.