Tourists visit South Africa’s game reserves to see lions and leopards, not rivets and servals.
Managers of these parks respond to this commercial pressure and tend to favor the larger, charismatic predators. Although the South African species of smaller carnivores play more than 30 important roles in their ecosystems by keeping the population of prey species in check, which in turn affects plant communities, managers pay little or no attention to their protection.
The assumption has long been that the addition of lions to the top of the food chain will lead to healthier populations of these other carnivorous species, and that efforts to protect large predators, such as lions, will also automatically benefit smaller animals. However, scientists have no evidence as to whether these predictions take place in the real world, especially in small reserves of the type found in South Africa.
A study published Wednesday in the journal Proceedings of the Royal Society B shows that the dynamics are more complex than previously thought. While the presence of lions slightly increases the number of small carnivorous species that live in an area, it reduces their overall range of distribution.
“We can not just assume that if we get along with lions, there will be benefits for the whole biodiversity,” said Gonçalo Curveira-Santos, a doctoral candidate in conservation biology at the University of Lisbon and a lead author of the findings . . “Apex predators are very interactive in an ecosystem, and we need to take better account of their ecological effect.”
Many game reserves in South Africa are former livestock farms that have been converted to ecotourism. If lions are present, it is usually re-introduced.
“We are not talking about pristine landscapes where lions roam free,” he said. Curveira-Santos said. “We are talking about small, fenced reserves where lions are placed after landscapes have been severely disturbed.”
After reintroduction, managers tend to invest a lot of money and effort in maintaining lion populations, including patrols against poaching and regular removal of game traps that are placed in reserves in local communities.
Mr Curveira-Santos and his colleagues wanted to see what effect, if any, those activities had on small carnivorous species weighing less than 44 pounds. They focused on 17 reserves in the provinces of Limpopo and KwaZulu-Natal in South Africa, of which about half reintroduced lions into their properties. They used camera trap data collected by conservation group Panthera to estimate the number of small carnivorous species in each reserve and to calculate the extent of their presence.
Across the reserves, the researchers recorded 22 small carnivorous species, ranging from foxes along the side and banded mangoes to foxes with bats. They found that the total number of species was slightly higher in the reserves with lions, but that lions on average reduced the amount of soil on which small carnivores occur by about 30 percent.
Mr. Curveira-Santos says it is clear that the lions, when present, influence the distribution of these smaller carnivores.
“The question is, is it the natural role and a good thing for conservation, or is it a negative thing because we do it in a very artificial way?” he said.
It could be that there are fewer individual small carnivores, because lions kill or otherwise suppress them, he said, or that lions cause small carnivores to avoid certain areas for fear – or both. The team also cannot say whether these dynamics affect the ecological roles of small carnivores. More study is needed, but if smaller predators are killed by lions or confined to certain places where the big cats do not trample, it can lead to a decrease in populations of these species and cause imbalances for other animals and plants.
Kelly Anne Marnewick, a carnivore biologist at the Tshwane University of Technology in South Africa, who was not involved in the research, said the reintroduction of lions at these South African reserves was valuable, with the predators now known as the “least concern” for conservation purposes.
“However, we need to take note of the findings of this article and do research to ensure that we have sufficient information to adapt management to a more holistic approach to benefit the entire ecosystem,” she said.
With further investigation, Mr. Curveira-Santos and his colleagues to determine how much overlap exists between the commercial interests of ecotourism and the ecological conservation community.
“We have just begun to unravel the complexities of carnivore community diversity and dynamics,” he said. “More research is needed before we can say how many management and conservation priorities match.”