Thursday, February 10, 2022

Notches on lions’ teeth reveal poaching in Zambia’s conservation areas

UCLA biologist Paula White displays two leopard skulls.
Credit: Paula White

In a hunting camp in Zambia more than a decade ago, UCLA biologist Paula White puzzled over the heavy skull of a trophy-hunted lion. Zambia permits limited hunting in certain areas to help fund its national conservation program, and White had gained permission to examine the trophy skulls and hides to evaluate how hunting was affecting conservation efforts.

This particular skull had a pronounced horizontal V-shaped notch on one of the canine teeth — a marking White had never seen before from natural wear. Over the next few months, she began noticing similar notches on other lions’ teeth.

It wasn’t until three years later, when she visited lions bred in captivity and saw them gnawing on a wire fence, that it clicked: The tooth notches in wild lions resulted from the animals chewing their way out of wire snares — noose-like traps set by poachers. The sheer number of notched teeth she’d seen suggested that such traps, illegal in conservation areas, were injuring far more lions than experts had estimated.

“It was an odd mix of thrilling to figure out the cause of the notches and horrifying to realize that so many animals had been entangled in a snare at some point in their lives,” said White, director of the Zambia Lion Project and a senior research fellow with the Center for Tropical Research at UCLA’s Institute of the Environment and Sustainability.

From 2007 to 2012, White crisscrossed Zambia examining and photographing the skulls, teeth and hides of trophy-hunted lions and leopards. She shared the photos with UCLA paleobiologist Blaire Van Valkenburgh, a carnivore tooth-wear expert.

They examined White’s photos of 112 lions and 45 leopards in two Zambian conservation areas and found that 37% of the lions and 22% of the leopards had snare scars and tooth notches, according to a study published today in the journal Frontiers in Conservation Science.

“Identifying the snare damage to the teeth is a real innovation. I’d never seen anything like those horizontal notches before,” said Van Valkenburgh, a professor emerita of ecology and evolutionary biology. “Usually I’m looking at decades-old skulls in museums, but these are the animals we’re trying to conserve right now. This is real-time information, and that’s what you need for conservation decisions.”

Lion’s canine tooth with a telltale horizontal notch — a sign that it had been trapped by a poacher’s snare.
Credit: Paula White
With lions and leopards having declined in numbers across their former African range and both now classified as “vulnerable,” vigorous conservation efforts are particularly important, the researchers said. The paper recommends requiring trophy hunters to share remains for forensic examination, which would help show whether current conservation programs are effectively reducing the number of human-caused injuries to the animals from illegal activities like poaching.

The researchers were surprised by the findings that more than a third of the lions and more than a fifth of the leopards White examined in the Luangwa Valley and Greater Kafue Ecosystem — which include Zambia’s largest conservation areas — had old snare injuries, even though they suspected existing data undercounted the problem. Previous estimates suggested that only 5% to 10% of Zambia’s lions had snare injuries, and there was virtually no prior data on such injuries among the nation’s leopards.

The authors also discovered that 30 of the 112 lions had shotgun pellets embedded in their skulls and that 13 of these 30 had both shotgun and snare injuries.

The study authors noted that overall rates of injuries among animals in the conservation areas are probably even higher than the current study suggests because researchers can’t count snared animals that never escaped or died undetected.

Some of the lions and leopards are injured or killed when they become unintended victims of wire snares set by poachers to catch wild game, while others fall victim to traps meant to protect poaching camps. Some poachers intentionally capture the big cats to sell their claws, teeth and other body parts. The animals can also be struck by shotgun pellets when people attempt to scare them away from livestock or homes.

Arrows indicate holes and sections of scaring where a lion was hit by shotgun pellets.
Credit: Paula White

Even for those that escape death, their injuries — damaged teeth, feet severed by snares and lead-shot poisoning — can seriously hinder their ability to compete for resources like food, mates and territory.

“Our new method of evaluating anthropogenic injuries provides a window into the stresses these carnivores are experiencing,” Van Valkenburgh said. “So for every trophy animal, a forensic examination such as ours should be routine. Studying the dead animals can help conserve the living animals.”

White’s research has already helped bring about policy changes by Zambia’s parks and wildlife department, which has lowered the number of lions that can be hunted annually by about two-thirds, stipulated that only older animals may be hunted and required that each trophy taken be examined by officials to confirm the age. Unfortunately, White said, problems like poaching and habitat encroachment continue to pose greater threats to conservation.

The paper recommends that countries expand their existing inspections by requiring hunters to provide their specimens for systematic photographic archiving to document tooth damage, snare scars or old embedded shotgun pellets before they export their trophies. The authors note that it’s also possible to detect snare-wear tooth injuries on tranquilized lions.

“I wholeheartedly believe that as long as hunting continues, scientists working with hunters can obtain information that would have been lost and which will really benefit conservation,” White said. “We could compare the past 10 years of data with data 10 years from now. I would hope that if the anti-poaching efforts are successful, we would see a reduction in these types of injuries.”

Source/Credit: University of California Los Angeles / Alison Hewitt

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