Yet, even unseen, their unique sound gave the previously undescribed species away. Named Dendrohyrax interfluvias, the chunky furball may appear similar to other hyraxes, but has a call that’s very distinct—more bark-like than the expected shrieking call from tree hyraxes in nearby areas. Simon Bearder, a co-author on the study and an emeritus professor at Oxford Brookes University in the UK, first became interested in the odd call in 2009. He was researching bush babies in western Nigeria with Oates when he noticed an unfamiliar sound in the night. It was a hyrax call, but unlike the ones he had heard on the other side of the Niger river. With decades of experience studying the sounds of nocturnal mammals in the region, Bearder says he knew right away that he was hearing something unique from other tree hyraxes. “It was immediately obvious to me. The calls were so different, they couldn’t be just closely related, they had to be completely different species.” In 2020, Bearder helped another research group identify a different, suspected distinct tree hyrax species in the Taita Hills in Kenya, also through analyzing vocal calls. The more recent—and more comprehensive— 2021 study provides a path forward for the Kenya research group and others, says Hanna Rosti, a nocturnal mammal researcher at the University of Helsinki who lead the 2020 study. “I’ve been reading it with fascination because I can see that this is what we have to do.”Rosti fell into hyrax research while studying primates, and went from viewing the animals as “weird rodents in the trees” to understanding their true evolutionary uniqueness. “They’re really extraordinary,” she says. “I call them fat balls because they look like a fat ball moving in a tree and their feet are so tiny,” says Rosti, “[their feet] look like small sausages, and they can still climb unbelievably well. I can’t understand how they can climb so elegantly with these sausage-like toes and very round bodies.” As comprehensive as the new study is, though, it isn’t perfect. “[The researchers have] done a really great job in terms of just the number of different angles from which they approached this,” says Paulette Bloomer, a professor of genetics at the University of Pretoria in South Africa who researches hyraxes and was not involved in the study. But she points out that their genetic sample size of 21 individuals is small, contains some gaps, and the portion of genome the researchers looked at likely isn’t telling the whole story. She adds that, although the vocal call data is very strong and the physical analysis also supports the findings, Bloomer may have waited for more genetic data before officially declaring a distinct species. “I’m a very cautious person,” she says. “I would have said, ‘this is an evolutionarily significant unit’. We need to sample in those gaps to understand the radiation of this group.” She hopes that further research addresses those missing pieces, and believes it will reveal even more new species.“I would not be surprised if we’re going to discover a lot more tree hyrax species in Africa,” says Bloomer. The newly described species could also be a boon to local conservation efforts. Dendrohyrax interfluvias is likely unique to the small area it was found in, putting it at an increased risk of extinction. Climate change, habitat loss, and human expansion already pose a possible threat to the newly christened hyrax. But Oates says recognizing it as a distinct species gives conservationists a way in. “You can go to your government officials and say, ‘look, do you realize you have a unique animal here, among these others, and nowhere else in the world? Here is another reason to try and conserve this.’”
