Paula White, a wildlife biologist, was examining lion skulls to estimate the animals’ ages when she noticed something odd about their teeth. Instead of just showing the normal, gradual wear and tear that occurs over time, a sharp V-shaped notch has been cut into the back edge of some of the big cats’ canines.
The bizarre marks turned out to have been caused by snares – circular wire traps that tighten like a noose around an animal’s neck or leg. Snares are usually a death trap, but the lions whose skulls Dr. White was examining had apparently managed to escape by tugging at the wire with their teeth.
Putting this together “was a real a-ha moment,” said Dr. White, an affiliate researcher at the University of California, Los Angeles. “It was a little gruesome but fascinating at the same time.”
Dr White and his colleague, Blaire Van Valkenburgh, a vertebrate paleobiologist also at UCLA, realized they had stumbled upon a valuable dataset, which would allow them to calculate the frequency of non-fatal human-caused injuries. to large carnivores.
Their findings, published Thursday in the journal Frontiers in Conservation Science, were worse than expected. More than a third of the lions and a fifth of the leopards they examined had evidence of being trapped at some point in their lives. More than a quarter of the lions also had shotgun pellets embedded in their skulls, indicating a previous run-in with poachers or other people.
“If we want these big cats to thrive, we need better data on the nature and scale of the threats they face, especially from humans,” said Dr Van Valkenburgh. “We can get this data by documenting the history of insults recorded in their bones and teeth.”
African lions are in precipitous decline. Between 1993 and 2014, population numbers fell by 43%, to just over 23,000 wild individuals today. Less complete evidence indicates that leopard numbers are also declining.
Habitat loss is the primary threat to lions and leopards, but humans also pose a significant threat to big cats through poaching. Although the illegal international trade in lions and other big cats is on the rise, for now big cats killed in retaliation for livestock predation are the biggest problem. Others are killed by traps set for animals such as gazelles and antelopes that are part of the bushmeat trade. Traps interfere with the survival of big cats by eliminating the prey they depend on for food, as well as accidentally catching and killing predators.
It is however difficult to determine the full extent of the impact of the trap and conflicts with people. Animals are often killed in very remote locations and cases go unreported. “Most often the animals go missing and you don’t know what happened to them,” Dr White said. If wildlife officials do manage to collect data, it’s usually for fatalities rather than injuries.
The researchers aren’t sure how the injuries they’ve documented may affect lions and leopards, but they suspect it must be significant.
“You are looking at an animal that depends on its ability to hunt and take down large prey, which is not an easy way to make a living,” Dr White added. “Any type of physical injury is going to make life more difficult for him.”
The new research — likely the first to systematically document such injuries — arose by chance. Dr White originally worked with the Zambian government on a project that photographed the skulls and skins of adult male lions and leopards that had been legally hunted as trophies in the Luangwa Valley and Greater Kafue ecosystem in Zambia .
The archived photos were the starting point for the new study. Examining the skulls, Dr White and Dr Van Valkenburgh found that 37% of the 112 lions and 22% of the 45 leopards had evidence of having been ensnared at some point in their lives. And 27% of the lions had been shot in the face with shotgun pellets.
The results are almost certainly understated. For the snaring calculations, the researchers only considered animals that had both worn teeth and corresponding scars on their skins — not those that only had worn teeth. For the shotgun estimates, they could only examine images of the animals’ skulls, not their entire skeletons. As Dr. White said, “Our reported numbers are moderately low, if high.”
Although the results cannot be directly extrapolated to other lion and leopard habitats, Dr Van Valkenburgh stressed that the approach “is easily replicable in countries without deep pockets or access to sophisticated technology”.
Joel Berger, a biologist at Colorado State University and the Wildlife Conservation Society, who was not involved in the study, agreed that the new method has “really broad value.”
“This is a remarkable paper that uses an imaginative diagnostic approach,” he said.
Human-caused carnivore deaths are a significant problem globally, but very few studies provide local insight into the problem, Dr. Berger continued. However, this kind of fine-scale information is needed if wildlife managers want to do more than make blind guesses about how best to help carnivores survive.
According to Amy Dickman, a conservation biologist at the University of Oxford, the “valuable and alarming” findings of Dr White and Dr Van Valkenburgh “suggest that pitfalls and conflict may be even more intense threats than we realize. had estimated it before”.
This highlights the need to prioritize finding solutions to these problems, Dr. Dickman added. As an example, she said people would be less likely to trap animals if they had access to enough food, and they would be less likely to fight back against predators if they received education and support. to better protect themselves and their livestock. Engaging people directly in conservation and ensuring they derive tangible benefits from living alongside wildlife is also part of the solution, Dr Dickman said.
Conservation is complex, however, and even in the best of times, wildlife can still cope with human pressure. The landscapes in Zambia where the study took place, for example, are considered strongholds of conservation, with strong anti-poaching programs and community engagement. That human-wildlife conflict is so high even in these places was a sobering revelation, Dr White said.
“It’s hard to say ‘increase the effort’ because clearly there’s already a lot of effort on the ground,” she said. “But if it doesn’t work, you have to think about it again.”