The fate of the lion, one of Africa's largest predators, may be even bleaker than we thought. According to a new study, lion numbers in West, Central, and East Africa could shrink by half over the next two decades even as populations in southern Africa hold steady or swell. The regional differences, authors say, come down to how closely the lions are managed. But some researchers question whether the prospects for lions in East Africa—their historical stronghold on the continent—are as grim as the study claims.Rat Noradrenalin (NA) ELISA Kit
Today, lions survive in the wild in 27 countries, all but a handful of them in Africa. In 1980 an estimated 75,000 roamed free. Since then, thousands have perished from poisoning, poorly regulated sports hunting, and the loss of habitat and prey. Until recently, scientists were relatively confident that roughly 30,000 remained. But this year a top conservation body, the International Union for Conservation of Nature, revised that estimate closer to 20,000.
Lions are a bit like restaurants—the fate of both may hinge upon their location. In West and Central Africa pressure from the human population is high and conservation efforts are low, so the projected declines there are no surprise, says Hans Bauer, a lion researcher at the University of Oxford who is based in Ethiopia and lead author on the new paper. “But we had thought that lions in both southern and eastern Africa were doing sort of okay,” he says.
To find out whether that was accurate, Bauer and other scientists compiled and analyzed data from surveys of 47 lion populations found in protected areas across Africa and then estimated the growth rate of each. Their analyses revealed a steep decline in almost all lion populations in West-Central Africa and a 67% chance that the region’s lion population will decline by 50% over the next 20 years, the researchers report online today in the Proceedings of the National Academy of Sciences. In East Africa, the team found a similar—although less steep—decline and estimate a 37% chance its lion numbers will shrink by 50% over the next 2 decades, too.
In contrast, the team found that lions in the southern African countries of Botswana, Namibia, Zimbabwe, and South Africa were doing “extremely well,” with their numbers even increasing in some parks, Bauer says.
The regional differences, he says, can be explained by how the animals are managed. In East Africa, lions are left free to roam across the landscape much as they have for thousands of years. In southern Africa, however, lions live in well-funded, intensively managed populations, often surrounded by fences that keep the cats in and people out.
The lack of adequate protections in East Africa could spell trouble for the felines—especially as the human population continues to grow—says Craig Packer, a lion researcher and ecologist at the University of Minnesota, Twin Cities, and one of the study’s co-authors. “We’re in danger of losing lions from the iconic savanna landscapes of East Africa because the mechanisms that are in place to protect them there are inadequate,” he says. Such loss could have ripple effects across the entire ecosystem.
However, some researchers question whether the data really support the authors' projections for East Africa. “While I might agree that lions are in trouble in West Africa based on what they’ve presented, in East Africa, it’s a bit of a toss-up," says Stuart Pimm, a conservation biologist at Duke University in Durham, North Carolina
The largest lion populations in East Africa—those in Serengeti National Park in Tanzania and Maasai Mara National Reserve in Kenya—are either increasing or experiencing only a slight decline, Pimm notes. The one clear big decline is in Katavai National Park in Tanzania, but those data, which show a steep drop-off from roughly 600 lions in the park in 1996 to zero in 2002, are highly controversial and shouldn’t be used to support the argument for a massive regional decline, he says.
Tim Caro, a wildlife biologist at the University of California (UC), Davis, who has worked in Katavi for years, agrees. “It’s simply not true that there are no lions in Katavi. If you go to the park now, you’re going to see them around the tourist circuit.”
Still, for other experts, the debate seems to be over whether the prospects for lions are bad or worse. “The research is more documentation of the type of rapid decline we know is happening, with lions and with much of the rest of African wildlife,” says Laurence Frank, a lion researcher at UC Berkeley, who wasn’t involved in the study. “The evidence keeps mounting.”