After humans, the lion is indisputably the top predator in Africa’s Serengeti. Since the 1990s, the big cats have been regarded as serious threats to the survival of both cheetah and wild dog populations. But a new study reveals that cheetahs are more adept at living with the lions than previously recognized, although wild dogs don’t fare so well. The work is likely to alter approaches to protecting all three carnivores.
Lions were first fingered as being particularly tough on Africa’s cheetahs in 1994. A researcher documented the big cats attacking and killing up to 57% of cheetah cubs in Tanzania’s Serengeti National Park. (They rarely ate the cubs, although the cheetah mothers often consumed the remains of their offspring after the lions had left.)
Things seemed almost as bad for African wild dogs, long-legged canines that are not related to domestic dogs. They have colorful, patchy coats and hunt ungulates such as wildebeest and gazelle. In the park, researchers documented that as the lion’s population surged (it nearly tripled from less than 50 to nearly 200 between 1966 and 1998 because of increasing numbers of prey, particularly wildebeest), the wild dogs, which had once numbered about 50, declined. Eventually, in 1992, the animals vanished from Serengeti National Park altogether, although small numbers persisted in lion-free areas outside the park’s boundary. Biologists have estimated that lions kill up to 32% of the canines.
Scientists noted the same pattern in fenced reserves in southern Africa, with lions ruling and smaller predators suffering. It’s easy to see why: Brawny African lions tip the scales at 120 to 180 kilograms, while cheetahs pack only 25 to 40 kg, and wild dogs weigh in at a mere 18 to 25 kg. But scientists still do not know why lions kill the smaller predators, which don’t compete directly with the big cats for prey.
Lions’ dominance has led some researchers to argue that efforts to protect cheetahs and wild dogs should be focused primarily on areas with few or none of the larger carnivores. Indeed, after a study in 2011 suggested that actively conserving lions might push cheetahs to the brink of extinction, some scientists advocated reconsidering strategies for protecting the big cats. Some have even suggested reducing their numbers, says Alexandra Swanson, a graduate student in ecology at the University of Minnesota, Twin Cities, and the lead author of the new study. “It was a controversial paper, and so I decided to test the idea that African lions suppress the populations of cheetahs and wild dogs.”
Drawing on data from three long-term projects that have monitored lion, cheetah, and wild dog populations in Serengeti National Park, Swanson and her colleagues examined how the three species used the park’s habitats and calculated the chance of cheetahs and wild dogs encountering a lion within the park. They also analyzed the population densities of the animals and the amount of available prey in fenced reserves in South Africa.
The results were clear: In the park, the increasing lion population has not triggered a drop in cheetah numbers; the smaller cats have remained stable, despite losing many of their cubs. But the lions (as well as a bout of canine distemper and rabies) had unquestionably spelled the end of the wild dogs in the park. Dogs that have managed to hang on in the Serengeti ecosystem live in marginal areas on the park’s edges. The researchers found a similar pattern in the South African fenced reserves. Those with numerous lions had fewer wild dogs, yet the cheetah populations were stable, the researchers report this week in the Journal of Animal Ecology.
Why the difference? Swanson’s team suggests that wild dogs “are so intent on avoiding lions” that they simply “get kicked out of huge areas of the landscape.” In contrast, cheetahs are able to use those same areas by carefully monitoring the lions and staying 100 meters away from them—thus, lions rarely kill adult cheetahs. The largely solitary cheetahs also attract less attention than do the noisy, conspicuous packs of wild dogs.
And cheetahs are apparently able to compensate for the loss of their cubs, perhaps because females become fertile within 2 weeks of losing their offspring. In contrast, lions target wild dogs of all ages, and the dogs’ packs don’t recover quickly when they lose adults.
Most intriguingly, cheetah females often set up their dens precisely where there are the most lions. “It is counterintuitive,” Swanson says, “and we don’t have a good explanation yet. But den sites are limited, and these are where the best resources are for raising their cubs, so it may be that the benefits outweigh the risks.”
The study offers a “plausible mechanism” for the cheetahs’ success, says John Fryxell, a wildlife ecologist at the University of Guelph in Canada, who was not involved in the research. The spotted cats practice a “fine scale behavioral avoidance of the lions, a sort of carnivorous ballet.”
Wild dogs, unfortunately, don’t have the dance moves of the cheetahs, and they lose out when lions are abundant, particularly on the open plains of the Serengeti. “They do better at coexisting in densely wooded areas, such as Selous National Park [in Tanzania] and Kruger National Park [in South Africa], where there’s more cover,” Swanson says.
The report “shows the complexity of inter-relationships between large carnivores,” says Luke Hunter, a biologist and the president of Panthera, a conservation organization in New York City. “People often underestimate how resilient and adaptable a species the cheetah really is. On the other hand, the paper elevates the conservation urgency for the African wild dog.”
As for the idea of culling lions to help these smaller predators? “That’s probably not an effective management policy,” Fryxell says. It’s far better to create larger reserves, reduce habitat loss, and persuade ranchers not to kill predators, large or small.